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Compatibility of a bivalent modified-live vaccine against Bordetella bronchiseptica and CPiV, and a trivalent modified-live vaccine against CPV, CDV and CAV-2.

Eight puppies (group 1) were vaccinated once with a bivalent modified-live vaccine against infectious tracheobronchitis by the intranasal route and at the same time with an injectable trivalent vaccine against canine parvovirus, canine distemper virus and canine adenovirus; a second group of eight puppies (group 2) was vaccinated only with the intranasal bivalent vaccine, and a further eight puppies (group 3) were vaccinated only with the injectable trivalent vaccine. Three weeks later they were all challenged with wildtype Bordetella bronchiseptica and canine parainfluenza virus by the aerosol route, and their antibody responses to the five vaccine organisms were determined. Oronasal swabs were taken regularly before and after the challenge for the isolation of bacteria and viruses, and the puppies were observed for clinical signs for three weeks after the challenge. There were no significant differences in the puppies' titres against canine parvovirus, canine distemper virus and canine adenovirus type 2 between the groups vaccinated with or without the bivalent intranasal vaccine. After the challenge the mean clinical scores of the two groups vaccinated with the intranasal vaccine were nearly 90 per cent lower (P=0.001) than the mean score of the group vaccinated with only the trivalent injectable vaccine, and the puppies in this group all became culture-positive for B bronchiseptica and canine parainfluenza virus. There were only small differences between the rates of isolation of B bronchiseptica from groups 1, 2 and 3, but significantly lower yields of canine parainfluenza virus were isolated from groups 1 and 2 than from group 3.

Adenoviridae Infections↗

Influence of insurance status and vaccine cost on physicians' administration of pneumococcal conjugate vaccine.

OBJECTIVE: In 2000, heptavalent pneumococcal conjugate vaccine (PCV7) was recommended for children younger than 2 years, but its high cost relative to other universally recommended childhood immunizations and variability in insurance coverage for the vaccine raised concerns. We investigated the influence of PCV7 cost and insurance coverage on physician recommendation of PCV7 to their patients and administration of PCV7 in their practices. METHODS: We conducted a mail survey from April to July 2001 of a random sample of 833 pediatricians and 788 family physicians in 24 states with different vaccine financing strategies (Vaccines for Children [VFC]-only; enhanced VFC; universal purchase). Physicians specified the proportion of children in their practice with insurance coverage for PCV7, where they recommend administering PCV7, and whether they have concerns about the cost of PCV7. RESULTS: The response rate was 60%. Overall, 87% of physicians recommend PCV7 for children younger than 2 years (99% pediatricians; 68% family physicians). Among physicians who recommend PCV7, 98% said that they would administer the vaccine in their own practices for children whose insurance covers the vaccine. However, only 56% of physicians who recommend PCV7 reported that all children in their practices had insurance coverage for the vaccine, whereas 24% of physicians reported 86% to 99% of children with coverage and 20% reported <or=85% of children with coverage. Among physicians in the last group with the lowest PCV7 insurance coverage rates in their practices, only 44% said that they would administer the vaccine in their own practices to children without PCV7 coverage, compared with 62% of physicians who provide care to children with higher rates of PCV7 coverage. Physicians in states with VFC-only vaccine financing strategies for PCV7 are less likely to administer PCV7 in their own practices to children without coverage than physicians in states with enhanced VFC and universal purchase strategies (48% vs 64% vs 74%). Almost one third of physicians who recommend PCV7 are concerned about the cost of PCV7; those with cost concerns are more likely to recommend that children without insurance coverage for PCV7 receive the vaccine at a public health clinic rather than in their own practices (45% vs 29%). Physicians with cost concerns are also more likely to say that they now screen children for insurance coverage more than for previously recommended vaccines (52% vs 21% for physicians without cost concerns). CONCLUSIONS: Nationwide, physician adoption of PCV7 recommendations is high, but where physicians recommend that PCV7 be administered differs significantly by children's variable insurance coverage for the vaccine and by state vaccine financing strategies. Physicians' concerns about the cost of PCV7 may foreshadow their responses to future children's vaccines that may be even more expensive.

Age Distribution↗

Rotavirus vaccination and intussusception: can we decrease temporally associated background cases of intussusception by restricting the vaccination schedule?

OBJECTIVE: The first rotavirus vaccine that was licensed in the United States, RotaShield, could have prevented the enormous burden of rotavirus diarrhea in American children but left instead the unfortunate legacy that live oral rotavirus vaccines may be associated with a serious but rare adverse event: intussusception. Although large trials indicate that the next generation of rotavirus vaccines is not associated with this complication, many children likely will develop intussusception by chance alone in the 2-week window after immunization, raising concerns about whether these cases might be "caused" by the vaccine. Our objective for this study was to model and compare the number of temporally associated intussusception events that are expected by chance alone under 2 rotavirus vaccination strategies. METHODS: We used national vaccine coverage rates and age-specific incidence of intussusception by months to model the number of temporally associated cases of intussusception that are expected by chance alone for 2 potential vaccination strategies: a strict schedule, limiting immunization to children within 1 month of the designated age for each dose (ie, 60-89, 120-149, and 180-209 days for doses 1, 2, and 3, respectively) versus a free schedule whereby infants are immunized whenever they appear for their routine vaccines up to 1 year of age. RESULTS: The number of intussusception events during the 2-week postvaccination window was 24% lower for the strict versus the free schedule (138 vs 182, respectively). This reduction was attributable largely to the smaller number of infants who were immunized fully under the strict schedule (vaccine coverage for 3 doses, 67% vs 89%). The cumulative risk for intussusception's occurring by chance in the 2-week postvaccination window essentially was the same between schedules (4.59 vs 4.76 per 100000 doses). Most cases occurred after the second or third dose. CONCLUSIONS: Although an age-restricted vaccination schedule substantially reduced the number of intussusception events that were observed in the 2-week postvaccination window when compared with a schedule with fewer restrictions, this decrease was attributable to a lower rate of vaccine coverage rather than a safer schedule of vaccination. The risk for intussusception did not differ significantly between vaccination strategies. Public health policy and education messages for physicians and parents should be developed to anticipate intussusception events that will occur by chance alone but are temporally related to rotavirus vaccination.

Age Factors↗

Intramuscular injections within 30 days of immunization with oral poliovirus vaccine--a risk factor for vaccine-associated paralytic poliomyelitis.

BACKGROUND: In Romania the rate of vaccine-associated paralytic poliomyelitis is for unexplained reasons 5 to 17 times higher than in other countries. Long ago it was noted that intramuscular injections administered during the incubation period of wild-type poliovirus infection increased the risk of paralytic disease (a phenomenon known as "provocation" poliomyelitis). We conducted a case-control study to explore the association between intramuscular injections and vaccine-associated poliomyelitis in Romania. METHODS: The patients were 31 young children in whom vaccine-associated paralytic poliomyelitis developed from 1988 through 1992. Eighteen were vaccine recipients, and 13 had acquired the disease by contact with vaccine recipients. Each of these children was matched with up to five controls according to health center, age, and in the case of vaccine recipients, history of receipt of the live attenuated oral poliovirus vaccine. Data were abstracted from medical records that documented the injections administered in the 30 days before the onset of paralysis. RESULTS: Of the 31 children with vaccine-associated disease, 27 (87 percent) had received one or more intramuscular injections within 30 days before the onset of paralysis, as compared with 77 of the 151 controls (51 percent) (matched odds ratio, 31.2; 95 percent confidence interval, 4.0 to 244.2). Nearly all the intramuscular injections were of antibiotics, and the association was strongest for the patients who received 10 or more injections (matched odds ratio for > or = 10 injections as compared with no injections, 182.1; 95 percent confidence interval, 15.2 to 2186.4). The risk of paralytic disease was strongly associated with injections given after the oral polio virus vaccine, but not with injections given before or at the same time as the vaccine (matched odds ratio, 56.7; 95 percent confidence interval, 8.9 to infinity). The attributable risk in the population for intramuscular injections given in the 30 days before the onset of paralysis was 86 percent (95 percent confidence interval, 66 to 95 percent); that is, we estimate that 86 percent of the cases of vaccine-associated paralytic poliomyelitis in this population might have been prevented by the elimination of intramuscular injections within 30 days after exposure to oral poliovirus vaccine. CONCLUSIONS: Provocation paralysis, previously described only for wild-type poliovirus infection, may rarely occur in a child who receives multiple intramuscular injections shortly after exposure to oral poliovirus vaccine, either as a vaccine recipient or through contact with a recent recipient. This phenomenon may explain the high rate of vaccine-associated paralytic poliomyelitis in Romania, where the use of intramuscular injections of antibiotics in infants with febrile illness is common.

Anti-Bacterial Agents↗

Vaccine beliefs of parents who oppose compulsory vaccination.

OBJECTIVES: Our objectives were the following: (1) to describe the sociodemographic factors, vaccine beliefs, and behaviors that are associated with parental opposition to compulsory vaccination, and (2) to determine if the availability of a philosophical exemption in a parent's state of residence is associated with parental opposition to compulsory vaccination. METHODS: Data from the 2002 HealthStyles survey were analyzed. Chi-square analysis was used to identify significant associations between belief and behavior questions and opposition to compulsory vaccination for school entry. Multivariate logistic regression was conducted using significant variables from the bivariate analysis to identify independent predictors of opposition to compulsory vaccination among surveyed parents. RESULTS: Of respondents with at least one child aged < or = 18 years living in the household (n=1,527), 12% were opposed to compulsory vaccination. Survey results indicate that a parent's belief regarding compulsory vaccination for school entry is significantly associated with beliefs in the safety and utility of vaccines, as well as intention to have the youngest child fully vaccinated. Residence in a state that permits philosophical exemption to vaccination also was significantly associated with a parent's opposition to compulsory vaccination for school entry. CONCLUSIONS: Providing basic information to parents regarding vaccines and vaccine-preventable diseases may help reduce opposition to compulsory vaccination by reinforcing the safety and importance of routine childhood vaccinations.

Adolescent↗

Prime-boost vaccination with plasmid and adenovirus gene vaccines control HER2/neu+ metastatic breast cancer in mice.

INTRODUCTION: Once metastasis has occurred, the possibility of completely curing breast cancer is unlikely, particularly for the 30 to 40% of cancers overexpressing the gene for HER2/neu. A vaccine targeting p185, the protein product of the HER2/neu gene, could have therapeutic application by controlling the growth and metastasis of highly aggressive HER2/neu+ cells. The purpose of this study was to determine the effectiveness of two gene vaccines targeting HER2/neu in preventive and therapeutic tumor models. METHODS: The mouse breast cancer cell line A2L2, which expresses the gene for rat HER2/neu and hence p185, was injected into the mammary fat pad of mice as a model of solid tumor growth or was injected intravenously as a model of lung metastasis. SINCP-neu, a plasmid containing Sindbis virus genes and the gene for rat HER2/neu, and Adeno-neu, an E1,E2a-deleted adenovirus also containing the gene for rat HER2/neu, were tested as preventive and therapeutic vaccines. RESULTS: Vaccination with SINCP-neu or Adeno-neu before tumor challenge with A2L2 cells significantly inhibited the growth of the cells injected into the mammary fat or intravenously. Vaccination 2 days after tumor challenge with either vaccine was ineffective in both tumor models. However, therapeutic vaccination in a prime-boost protocol with SINCP-neu followed by Adeno-neu significantly prolonged the overall survival rate of mice injected intravenously with the tumor cells. Naive mice vaccinated using the same prime-boost protocol demonstrated a strong serum immunoglobulin G response and p185-specific cellular immunity, as shown by the results of ELISPOT (enzyme-linked immunospot) analysis for IFNgamma. CONCLUSION: We report herein that vaccination of mice with a plasmid gene vaccine and an adenovirus gene vaccine, each containing the gene for HER2/neu, prevented growth of a HER2/neu-expressing breast cancer cell line injected into the mammary fat pad or intravenously. Sequential administration of the vaccines in a prime-boost protocol was therapeutically effective when tumor cells were injected intravenously before the vaccination. The vaccines induced high levels of both cellular and humoral immunity as determined by in vitro assessment. These findings indicate that clinical evaluation of these vaccines, particularly when used sequentially in a prime-boost protocol, is justified.

Animals↗

United States vaccine research: a delicate fabric of public and private collaboration. National Vaccine Advisory Committee.

In the last 20 years, two thirds of all new vaccines provided worldwide have been produced by a US network of independent industrial, governmental, and academic partners engaged in vaccine research and development. Vaccines are complex products and the science of vaccinology is difficult. To achieve the full promise of modern science and technology to prevent and treat disease by immunization, the delicate fabric of America's cooperative and collaborative vaccine research relationships must be sustained and strengthened. The major partners are the federal government; four large companies--two US-headquartered (Wyeth-Lederle Biologics and Vaccines and Merck & Co), two foreign firms (SmithKline Beecham and Pasteur Mérieux Connaught); and academia. Of the $1.4 billion that fund US vaccine research and development annually, 46% comes from vaccine sales, 36% from taxpayers, and 18% from risk capital. Vaccine innovation could be strengthened by improved public and policy maker understanding of the vaccine development network; declarations of partnership; interactive dialog with federal advisory bodies; public forums for government and industry to listen to patients, providers and researchers; sabbatical assignments between partners; mechanisms to share industries' market research with public immunization programs; continued active industry participation in the Advisory committee on Immunization Practices and the National Vaccine Advisory committee; increased collaboration between industry and the National Institutes of Health for clinical research; harmonization of the Advisory Committee on Immunization Practices vaccine recommendations and the Food and Drug Administration package inserts; and public policies to foster the partnership's collaboration and robustness. The optimal size and configuration of the US vaccine enterprise should be debated only in the context of a full understanding of how the current system works and its record of effectiveness. These National Vaccine Advisory Committee recommendations are directed at developing public policies to foster and sustain vaccine innovation and ensure the timely introduction and supply of new vaccines needed by this nation and the world.

Cooperative Behavior↗

Influence of a reovirus-antibody complex vaccine on efficacy of Marek's disease vaccine administered in ovo.

Two experiments determined the influence of an experimental reovirus-antibody complex vaccine on Mareks disease virus (MDV) vaccine when used in ovo. Designs were the same except that specific-pathogen-free (SPF) broiler eggs were used in Experiment 1 and commercial broiler eggs with maternal antibodies against reovirus were used in Experiment 2. At 18 days of incubation, embryos were separated into four groups and inoculated with either diluent, MDV vaccine, reovirus-antibody complex vaccine, or a combination of reovirus-antibody complex and MDV vaccine. At 5 days of age, half the chickens in each group were challenged with MDV. At 7 wk old, all were euthanatized, weighed, and examined. At 7 days of age, remaining chickens in each group were challenged with reovirus. At 21 days old, chickens were euthanatized and weighed. No vaccine adversely affected hatchability or posthatch mortality in SPF or commercial chickens. There were no significant differences in protection against reovirus challenge when vaccines were used separately or in combination, and lesion scores were nearly identical in all vaccinated groups in both experiments. However, percentage of protection against reovirus was lower in Experiment 2, indicating an adverse effect of maternal immunity on efficacy of the reovirus vaccine. There were no significant differences in protection against MDV when the vaccines were used separately or combined. Severity of MDV lesions was nearly identical in all vaccinated groups in both experiments. However, the combination of vaccines gave numerically lower protection against MDV than MDV vaccine alone. Use of a larger number of birds, as in field conditions, may result in statistically lower protection for the vaccine combination. Large field trials are needed to determine the potential of the reovirus-antibody complex vaccine.

Animals↗

Comparison of toxicities of acellular pertussis vaccine with whole cell pertussis vaccine in experimental animals.

There is no suitable animal model for pertussis encephalopathy in humans. In this study, we have compared the toxicity of acellular pertussis vaccine with whole cell pertussis vaccine in mice or guinea pigs. Two lots of acellular and two lots of whole cell vaccine produced in different countries were assayed in the test. 1. There was no statistical difference in mouse protective potency between these acellular or whole cell pertussis vaccines. 2. There were no differences in chemical ingredients between acellular and whole cell pertussis vaccines except for protein nitrogen content. The protein nitrogen content of whole cell vaccine was at least three times higher than that of the acellular product. 3. Anti-PT antibody productivity of the acellular vaccine was higher than that of the whole cell vaccine. 4. Anti-agglutinogen antibody productivity of the whole cell vaccine was higher than that of the acellular vaccine. 5. There was no pyrogenic activity with the acellular vaccine, but high pyrogenicity was seen with whole cell vaccine. 6. There was high body-weight decreasing toxicity in mice and guinea pigs by the whole cell vaccine. 7. The mice died when they received whole cell pertussis vaccine iv, but no deaths occurred in the mice which received acellular pertussis vaccine.

Adhesins, Bacterial↗

The safety of acellular pertussis vaccine vs whole-cell pertussis vaccine. A postmarketing assessment.

OBJECTIVE: To determine the impact of the introduction of acellular pertussis vaccine for the fourth and fifth doses of the diphtheria and tetanus toxoids and pertussis vaccine series in children on rates of reported vaccine-associated adverse events in the United States. DESIGN: Analysis of postmarketing vaccine adverse event data from the Vaccine Adverse Event Reporting System during the years 1991 to 1993. POPULATION STUDIED: Approximately 27 million doses of diphtheria and tetanus toxoids and pertussis vaccine and 5 million doses of diphtheria and tetanus toxoids and acellular pertussis vaccine were distributed from 1991 to 1993 to children 15 months to 7 years of age. MAIN OUTCOME MEASURES: Rates of reported fever, seizures, and hospitalizations after pertussis vaccination. RESULTS: Rates of reported adverse events per 100,000 vaccinations were significantly lower after administration of diphtheria and tetanus toxoids and acellular pertussis vaccine than diphtheria and tetanus toxoids and pertussis vaccine for the following outcomes: all reports, 2.9 vs 9.8; fever, 1.9 vs 7.5; seizures, 0.5 vs 1.7; and hospitalizations, 0.2 vs 0.9. CONCLUSIONS: These results confirm that minor adverse events are less frequent after administration of the acellular pertussis vaccine. In addition, these data suggested that seizures and hospitalizations associated with pertussis vaccination are less frequent after administration of the acellular pertussis vaccine in age groups for which it is now recommended.

Child↗

Recombinant glycoprotein vaccine for the prevention of genital HSV-2 infection: two randomized controlled trials. Chiron HSV Vaccine Study Group.

CONTEXT: In the last 3 decades, herpes simplex virus type 2 (HSV-2) infection seroprevalence and neonatal herpes have increased substantially. An effective vaccine for the prevention of genital herpes could help control this epidemic. OBJECTIVE: To evaluate the efficacy of a vaccine for prevention of HSV-2 infection. DESIGN: Two randomized, double-blind, placebo-controlled multicenter trials of a recombinant subunit vaccine containing 30 microg each of 2 major HSV-2 surface glycoproteins (gB2 and gD2) against which neutralizing antibodies are directed, administered at months 0, 1, and 6. Control subjects were given a citrate buffer vehicle. Participants were followed up for 1 year after the third immunization. SETTING AND PARTICIPANTS: We enrolled 2393 persons from December 10, 1993, to April 4, 1995, who were HSV-2 and human immunodeficiency virus seronegative. One trial with 18 centers enrolled 531 HSV-2-seronegative partners of HSV-2-infected persons; the other, with 22 centers, enrolled 1862 persons attending sexually transmitted disease clinics. A total of 2268 (94.8%) met inclusion criteria and were included in the analysis with 1135 randomized to placebo and 2012 to vaccine. MAIN OUTCOME MEASURE: Time to acquisition of HSV-2 infection, defined by seroconversion or isolation of HSV-2 in culture during the study period by randomization group. RESULTS: Time-to-event curves indicated a 50% lower acquisition rate among vaccine vs placebo recipients during the initial 5 months of the trial; however, overall vaccine efficacy was 9% (95% confidence interval, -29% to 36%). Acquisition rates of HSV-2 were 4.6 and 4.2 per 100 patient-years in the placebo and vaccine recipients, respectively (P =.58). Follow-up of vaccine recipients acquiring HSV-2 infection showed vaccination had no significant influence on duration of clinical first genital HSV-2 episodes (vaccine, median of 7.1 days; placebo, 6.5 days; P>.10) or subsequent frequency of reactivation (median monthly recurrence rate with vaccine, 0.2; with placebo, 0.3; P>.10). The vaccine induced high levels of HSV-2-specific neutralizing antibodies in vaccinated persons who did and did not develop genital herpes. CONCLUSIONS: Efficient and sustained protection from sexual acquisition of HSV-2 infection will require more than high titers of specific neutralizing antibodies. Protection against sexually transmitted viruses involving exposure over a prolonged period will require a higher degree of vaccine efficacy than that achieved in this study.

Adolescent↗

Intranasal vaccination of pigs against Aujeszky's disease. 4. Comparison with one or two doses of an inactivated vaccine in pigs with moderate maternal antibody titres.

Intranasal (IN) vaccination of pigs with low levels of maternally-derived antibody (MDA) has previously been shown to confer good protection against challenge with virulent Aujeszky's disease virus (ADV). The objective of the present study was to determine the efficacy of IN vaccination with an attenuated ADV, in comparison with that of an inactivated vaccine given parenterally, in pigs with higher MDA titres at the time of vaccination. In one experiment, vaccinations were done at 6 weeks of age, and in another experiment pigs were vaccinated at 4 and/or 9 weeks of age. Two months after (the last) vaccination pigs were challenged intranasally with a virulent ADV. Protection was evaluated on the basis of mortality, periods of growth arrest, fever and virus shedding after challenge. The presence of MDA markedly depressed the serum-neutralizing antibody response after vaccination. Sensitisation occurred after parenteral vaccination with an inactivated vaccine despite high MDA levels. Although the intranasally-vaccinated pigs had lower levels of neutralizing antibody at the time of challenge, they were significantly better protected than pigs given 1 or 2 doses of the inactivated vaccine. Comparing the present results with those of a previous study, it appears that the efficacy of parenteral as well as intranasal ADV vaccination decreases with increasing levels of MDA at the time of vaccination.

Administration, Intranasal↗

Early appearance of neutralizing antibodies after vaccination with an inactivated hepatitis A vaccine.

Sera from 30 subjects vaccinated with the Pasteur Merieux Serums & Vaccins (PM) inactivated hepatitis A vaccine, and from 30 subjects vaccinated with the Smithkline Beecham (SB) inactivated hepatitis A vaccine, were tested in two laboratories in order to provide comparative data on neutralizing activities of vaccine-induced antibodies. Sera were also evaluated by a modified radioimmunoassay (mRIA) and results were compared to neutralization assays results. Neutralizing antibody titres provided by the two laboratories correlated well (coefficient or correlation 0.42, P < 0.001). Neutralizing antibodies were detected after vaccination with both vaccines, and the kinetics of neutralizing antibody were the same with both vaccines. The titres gradually increased between the second week after the first dose and the post-booster dose (week 28). A strong booster effect of the booster vaccine dose on neutralizing titres was observed. Significantly higher neutralizing antibody titres with the PM vaccine were observed as early immune response on week 2 titres on both series of results. Vaccine-induced neutralizing antibody titres and vaccine-induced antibody mRIA titres correlated well (coefficient of correlation 0.82 and 0.72, respectively, P < 0.0001 in both cases). These results demonstrate early appearance of neutralizing antibody at high titre with the PM vaccine.

Adolescent↗

The effect of reconstitution of an Haemophilus influenzae type b-tentanus toxoid conjugate (PRP-T) vaccine on the immune responses to a diphtheria-tetanus-whole cell pertussis (DTwP) vaccine: a five-year follow-up.

Controversial results have been obtained from previous studies on the combined administration of Haemophilus influenzae type b-tetanus toxoid conjugate (PRP-T) and diphtheria-tetanus-whole-cell pertussis (DTwP) combination vaccines, with regard to possible reciprocal interference between the constituent antigens. To document the priming effect and possible long-term immunogenic interference of PRP-T and DTwP combination vaccines, a randomized, double-blind, controlled study was conducted in Belgium. A total of 168 healthy infants received, at 3, 4 and 5 months of age, DTwP vaccine mixed just prior to injection either with PRP-T vaccine (group A, DTwP//PRP-T, N = 85) or with placebo (group B, DTwP//Placebo, N = 83). At the age of 14 months, children of both groups were randomized to receive either a dose of DTwP//PRP-T vaccine (subgroups A1 and B1) or a dose of Hib polysaccharide (PRP) vaccine (subgroups A2 and B2). Those children in subgroups A1 and B1 had an additional serum sample taken at the age of 5 years (at the time of a DT booster). The immune response to Hib polysaccharide at the age of 4, 5 and 6 months confirmed the excellent immunogenicity profile of PRP-T in infants. In addition, the vigorous anamnestic response (i.e. a 20-fold increase of GMT) to a booster dose of the plain capsular polysaccharide (PRP) reflected the efficient Hib-priming induced by the combined DTwP//PRP-T vaccine. Reconstitution of PRP-T with DTwP did not affect the immune response to diphtheria toxoid or pertussis agglutinins. Nevertheless, at almost any time point during the five-year follow-up, the tetanus antitoxin GMT values were significantly lower in the DTwP//PRP-T group (A and A1) than in the DTwP//Placebo group (B and B1). Despite the suppressive effect on GMT values, intergroup differences in rates of seroprotection were never significant, except after doses 2 and 3 for which there were lower percentages of children in group A with antitoxin titers > 0.05 IU/mL and > 1.0 IU/mL. In the group primed with the combined DTwP//PRP-T vaccine, (1) a DT booster dose at the age of 5 years provoked a 150-fold increase in tetanus antitoxin GMT, (2) a high tetanus antitoxin GMT value was attained (GMT = 19.3 IU/mL) and (3) all children in this group had tetanus antitoxin titers > 1.0 IU/mL, so it may be concluded that all these children will still be protected against tetanus until at least the age of the next recommended booster dose (i.e. the age of 15 years). No differences in the occurrence of adverse events were observed between the groups who received the DTwP//PRP-T vaccine or the DTwP//Placebo vaccine, both vaccines being associated with events customarily attributable to DTwP (data not shown). Our results indicate (1) that the combination vaccine, DTwP//PRP-T, represents a safe and effective alternative for the existing uncombined vaccines and (2) that the long-term effect of interference between the components of future combination vaccines should be studied with subsequent booster doses, followed by the evaluation of persistence of antibodies over several years.

Agglutination Tests↗

A cross-protection experiment in pigs vaccinated with Haemophilus parasuis serovars 2 and 5 bacterins, and evaluation of a bivalent vaccine under laboratory and field conditions.

Cross-protection between Haemophilus parasuis serovars 2 and 5 was examined in pigs using a bacterin based vaccine, and subsequently the safety and efficacy of a bivalent vaccine were evaluated. Upon intratracheal challenge of a serovar 2 or 5 strain, pigs immunized with a monovalent vaccine were protected against challenge with a homologous serovar strain, but not with a heterologous serovar strain. Immunization with a bivalent vaccine containing both serovars 2 and 5 bacterins conferred protection in pigs against lethal challenge with each of the serovar strains. A total of 86 pigs from two SPF herds were injected with the bivalent vaccine intramuscularly twice at a four-week interval. No adverse reactions following the vaccination were observed. On day 7 after the second vaccination, vaccinated and non-vaccinated control pigs from herd A were transferred to herd B, where Glasser's disease had broken out. Pigs in the control group developed clinical signs of the disease, and 6 of 8 (75%) pigs died until slaughter, in contrast with only 4 of 46 (9%) pigs in the vaccinated group. In herd C, where there was no outbreak of Glasser's disease, complement fixation antibody titer was raised only in the vaccinated group. A challenge experiment on days 20 and 79 after the second vaccination showed that only the vaccinated pigs were protected. From these findings, the safety and efficacy of the bivalent vaccine were confirmed under laboratory and field conditions.

Animals↗

The hunt for new tuberculosis vaccines: anti-TB immunity and rational design of vaccines.

Tuberculosis (TB) remains to be a leading infectious cause of death worldwide. Apparently, the current BCG vaccine that has been used for 80 years, has failed to control the TB epidemic. Hunting for improved TB vaccine formulations represents a daunting task to TB research community. Anti-TB host defense requires T cell-mediated immunity and we are in desperate need of enhanced understanding of how to develop a new generation of TB vaccines that are able to provoke potent and long-lasting protective cell-mediated immunity, different from almost all of the vaccines currently in use. It is of importance to successful TB vaccine development to identify the key cellular and molecular events governing the generation of anti-TB immunity, but unfortunately little has been understood as to why 90% of infected humans never develop active TB. However, waiting would not help us to win the battle and an ever-intensifying effort is being made to develop various new formulations according to the immunology that we have been learning, in large part, from experimental models. This review article attempts to unite the current understanding of anti-TB immunity with the rational design of anti-TB vaccines. It examines what may have confounded the immunogenicity of current BCG vaccine and the major obstacles to successful development of TB vaccines. It also discusses about antigen presentation, activation of Th1 and Tc1 cells, anti-TB immune effectors and the generation of memory T cells. The vaccine section describes four types of major TB vaccines under development: mycobacterial-, subunit-, plasmid DNA- and viral-based vaccines. A special section is dedicated to the rationale and current design of cytokine-based adjuvant formulations for TB vaccines. We also take this opportunity to introduce our recent development in cytokine transgene adjuvanted BCG vaccination and recombinant adenoviral-based TB vaccines.

Antigens, Bacterial↗

Results of vaccination of Asian elephants (Elephas maximus) with monovalent inactivated rabies vaccine.

OBJECTIVE: To evaluate the humoral immune response of Asian elephants to a primary IM vaccination with either 1 or 2 doses of a commercially available inactivated rabies virus vaccine and evaluate the anamnestic response to a 1-dose booster vaccination. ANIMALS: 16 captive Asian elephants. PROCEDURES: Elephants with no known prior rabies vaccinations were assigned into 2 treatment groups of 8 elephants; 1 group received 1 dose of vaccine, and the other group received 2 doses of vaccine 9 days apart. All elephants received one or two 4-mL IM injections of a monovalent inactivated rabies virus vaccine. Blood was collected prior to vaccination (day 0) and on days 9, 35, 112, and 344. All elephants received 1 booster dose of vaccine on day 344, and a final blood sample was taken 40 days later (day 384). Serum was tested for rabies virus-neutralizing antibodies by use of the rapid fluorescent focus inhibition test. RESULTS: All elephants were seronegative prior to vaccination. There were significant differences in the rabies geometric mean titers between the 2 elephant groups at days 35, 112, and 202. Both groups had a strong anamnestic response 40 days after the booster given at day 344. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed the ability of Asian elephants to develop a humoral immune response after vaccination with a commercially available monovalent inactivated rabies virus vaccine and the feasibility of instituting a rabies virus vaccination program for elephants that are in frequent contact with humans. A 2-dose series of rabies virus vaccine should provide an adequate antibody response in elephants, and annual boosters should maintain the antibody response in this species.

Analysis of Variance↗

Rabies oral vaccination of foxes during the summer with the VRG vaccine bait.

The vaccination of foxes by distributing vaccine baits in the environment was initiated in France in 1986. Two campaigns per year were carried out: one in the spring and one in the autumn. After the spring campaigns, only 22-52% of fox cubs consumed vaccine baits compared to 75% of the adults and 70-80% of the adults or fox cubs after autumn campaigns. In order to reduce the period of time during which fox cubs do not have access to baits and are not immunised, a vaccination campaign was organised during the summer of 1992 over a contaminated area of 25,748 km2 where vaccines had never previously been given. Vaccine bait stability was assessed during the same summer in the field and their appetence tested on captive foxes. The efficacy of the campaign was evaluated by the relative decrease in rabies incidence and the rate of bait uptake by foxes compared to those from neighbouring areas vaccinated for the first time with the same vaccine during the spring or autumn. Summer vaccination significantly increased (P < 0.01) bait uptake by fox cubs (71%) compared with spring vaccination (39%), but no significant difference was observed for adult foxes. Moreover, the decrease in rabies incidence, measured during the 6-month period following the campaigns was less pronounced after summer vaccination (49% decrease) than when the first vaccination was carried out during the spring or autumn (79 and 72% decrease, respectively). Three campaigns led to an apparent elimination of rabies when the first campaign was performed in the spring or autumn, but only to a 76% decrease in rabies incidence density index when the first campaign was performed during the summer. The high thermostability of the Raboral VRG bait permits its use during the summer for an emergency campaign. For routine vaccination plans, however, the classical calendar of spring and autumn vaccination campaigns should continue to be preferred.

Administration, Oral↗