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At least 127 records · Page 7Linked to original sources

PubMed1996

Experience with veterinary vaccines in warm climates.

After a short description of the African laboratories manufacturing veterinary vaccines, the authors explain the main constraints for the use, in the field, of veterinary vaccines in warm climates. The need to respect the cold chain from the supplier of vaccines to the recipient animal is emphasised. In the Ivory Coast, during national vaccination campaigns, it has been proved that the quality of the rinderpest and contagious bovine pleuropneumonia vaccines is satisfactory when there is no disruption in the cold transport services. The data of this survey are exposed. In the framework of a project entitled "Thermostable rinderpest Vaccine, Transfer of Technology", a thermostable vaccine has been developed. It is manufactured in different African laboratories and integrated in some Pan African Rinderpest Campaign (PARC) vaccination programmes. On the other hand, the prospects offered by new thermotolerant attenuated vaccines against Newcastle disease are exposed. Finally, the authors present an outlook on the development of thermoresistant veterinary vaccines, such as those produced by genetic engineering, in particular with pox virus vectors.

Africa↗

PubMed1997

Atomic and molecular imaging at the single-cell level with TOF-SIMS.

A complete cold chain freeze-fracture methodology has been developed to test the feasibility of using time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging for the molecular analysis of frozen hydrated biological samples. Because the technique only samples the first few monolayers of a sample, water on the surface of a sample can be a major source of interference. This problem can be minimized by placing a cold trap (fracture knife and housing at -196 degrees C) near the fractured sample that is held at a warmer temperature (-97 to -113 degrees C). This results in removal of surface water and prevents condensation on the surface. Although this approach is effective, it has been found that sample warming needs to be carefully controlled due to the volatility of other matrix molecules and the morphological effects imparted onto the cell surface during drying. By utilizing the above handling technique, it has been possible to demonstrate for the first time that TOF-SIMS imaging technology can be used to obtain images of molecular species across a cell surface with a submicrometer ion probe beam. Images of small hydrocarbons and the deliberately added dopants DMSO and cocaine have been obtained with TOF-SIMS of the single-cell organism Paramecium.

Animals↗

PubMed1999

Evaluation of self-taken samples for the presence of genital Chlamydia trachomatis infection in women using the ligase chain reaction assay.

The aim of this study was to evaluate the sensitivity and acceptability of self-taken vulval-introital (VI) samples, first-catch urine (FCU) samples and clinician-obtained cervical samples for the presence of genital Chlamydia trachomatis infections in women using the ligase chain reaction (LCR) assay. One hundred and four patients were enrolled, of whom 54 patients had chlamydial DNA in at least one of the samples tested. The sensitivity of the cervical sample was 96.3%, vulval-introital sample in LCR buffer 92.6%, vulval-introital swab collected dry 88.9%, FCU stored at +2-8 degrees C 81.5%, FCU stored at room temperature 77.8% and FCU stored with 2% w/v boric acid at room temperature 87.0%. Self-taken vulval-introital LCR samples were shown to be an acceptable alternative to a clinician-obtained LCR sample. The addition of boric acid may overcome the need for a continuous cold chain for FCU samples.

Adolescent↗

PubMed1993

Toxin production by Bacillus cereus in dairy products.

Spores of a known toxigenic and psychrotrophic dairy isolate of Bacillus cereus (HRM 44) were unable to grow and produce diarrhoeagenic toxin at 6 degrees C in creams and dairy-based products. These findings suggest that the production of B. cereus diarrhoeagenic toxin is unlikely to occur in creams and dairy-based products maintained within the cold chain. Growth and toxin production were readily demonstrated in creams and some desserts stored at 21 degrees C. Growth in creams was associated with obvious spoilage. However, in the flavoured desserts, spoilage was not always obvious before significant growth of B. cereus and toxin production had occurred. Dairy desserts with high sugar content and/or low pH did not support toxin production and these findings are discussed.

Bacillus cereus↗

PubMed1999

Physical, chemical and immunological stability of CHO-derived hepatitis B surface antigen (HBsAg) particles.

Recombinant hepatitis B surface antigen (HBsAg) particles derived from Chinese hamster ovary (CHO) cells were stored at various conditions for 12-18 months in their naked form or adsorbed to alum (HBV vaccine). The physical, chemical and immunological parameters during storage at -20 degrees C, 4 degrees C, room temperature and 37 degrees C were investigated. HBsAg particles fully retained the original peptide composition when stored for 6 months, as a dispersion, at -20 degrees C and 4 degrees C; and as lyophilized powder, at all four temperatures. Ten percent sucrose preserved the size, shape and protein content of the naked particles stored at 4 degrees C and -20 degrees C for 18 months as a dispersion or lyophilized. Lyophilization in the presence of glucose, sucrose and trehalose, but not mannitol, further improved the 4 degrees C stability of size, shape and the protein content during 2 years of storage. Stability of the particle's lipid components was inferior to that of the protein components. Dispersions of naked HBsAg and of particles lyophilized in the presence of sucrose and stored at -20 degrees C were the only forms in which the lipid content and composition, including the lipid polyunsaturated acyl chains, were preserved for at least 18 months storage. The level of phospholipid and free cholesterol were most stable in the HBV vaccine which was stored at 4 degrees C; they did not change after 1 year of storage. Preservation of immunogenicity was evaluated according to dose-dependent changes in S-specific antibody titers in sera obtained from immunized BALB/c mice. The ED50 for achieving seroconversion was 0.07 microg/ml/mouse, indicating that the vaccine is very immunogenic. Freezing or freeze-drying of the HBV vaccine results in the total loss of vaccine immunogenicity (in spite of the good chemical stability), while full immunological potency was retained for at least 2.5 years at 4 degrees C. Storing formulated vaccine at 25 and 37 degrees C for 4 and 2 weeks, respectively, did not alter the vaccine potency. This study suggests that the vaccine's physical, chemical and immunological characteristics are sufficiently stable at high temperatures to reduce the need for 'cold chain' transportation.

Animals↗

PubMed2002

Effect of holding conditions on the detection of West Nile viral RNA by reverse transcriptase-polymerase chain reaction from mosquito (Diptera: Culicidae) pools.

We evaluated the effect of holding temperature and time between mosquito death and processing mosquito pools for virus detection on our ability to detect West Nile (WN) viral RNA from pools of mosquitoes by reverse transcriptase-polymerase chain reaction (RT-PCR). Pools of 24 uninfected Culex pipiens L. mosquitoes were "spiked" with either a single Cx. pipiens that had been inoculated previously with WN virus or with an uninfected mosquito. These pools were held dry at 20, 4, -20, or -70 degrees C for selected time intervals before all mosquito pools were triturated in TRIzol LS reagent and processed for detection of WN viral RNA. While infectious virus virtually disappeared from pools maintained at 20 degrees C by 48 h after mosquito death, neither holding temperature (20 to -70 degrees C) nor holding period (up to 2 wk) affected detection of WN viral RNA by real-time RT-PCR. These findings suggest that we need not keep mosquitoes chilled to be able to detect WN viral RNA effectively by RT-PCR. This should enhance the feasibility of field-based WN virus surveillance programs where only detection of WN viral RNA is the objective and maintenance of a cold chain may not be possible.

Animals↗

PubMed1989

Stability of an antifertility vaccine consisting of gonadotropin subunits linked to tetanus toxoid.

The shelf life and thermal stability of an antifertility vaccine, in which gonadotropin subunits are linked to carriers such as tetanus toxoid and cholera toxin chain B and has successfully completed phase-I clinical trials at five centres in India, was studied. The vaccine adsorbed on alum was stored at three temperatures, 4 degrees C, room temperature (20-30 degrees C) and at 40 degrees C, for a period of up to 1 year. The human chorionic gonadotropin (hCG) binding capacity of antibodies (peak titres) induced in rodents by the vaccine after 6 months of storage at 40 degrees C and at room temperature were 1430 +/- 201 (mean +/- s.e.m.) and 1291 +/- 152 ng ml-1 respectively as compared to 1075 +/- 185 ng ml-1 for the vaccine stored at 4 degrees C. The difference was not statistically significant. After 12 months of storage, the immunogenic properties of the vaccine were nearly the same irrespective of the temperature at which the vaccine was kept. The findings show that the vaccine adsorbed on alum can withstand storage up to at least one year at room temperature and at 40 degrees C. These observations have implications for the current thoughts on storage of tetanus toxoid and diphtheria toxoid at 4-8 degrees C, the two vaccines widely used in immunoprophylaxis, and suggest that similar investigations on these vaccines as cold chain facilities are not universally available in developing countries.

Animals↗

PubMed1984

Control of measles by annual pulse immunization.

In a village with a population of more than 2,000, with measles outbreaks in alternate years, annual single-day measles immunization campaigns were conducted during four winter seasons. Measles vaccine was offered to children 1 year of age and older, with no previous measles or immunization. There has been no outbreak of measles since the introduction of immunization to date. Four cases of introduced measles did not result in any secondary case. This vaccine delivery strategy (annual pulse immunization), designed to improve coverage and simplify cold chain management, was shown to be suitable for the control of measles in rural communities in the Third World.

Child↗

PubMed2002

Detection of measles virus RNA in whole blood stored on filter paper.

The purpose of this study was to evaluate the use of dried blood spots stored on filter paper as a means to provide specimens for virologic surveillance for measles virus (MV) in situations when the reverse cold chain is not available. Two single-step RT-PCR assays were evaluated for sensitivity of detection of MV nucleoprotein gene RNA. The more sensitive assay was then used to assess the stability of MV RNA in dried whole blood stored on filter paper. MV RNA was found to be stable in dried blood spots for up to 2 months at room temperature or 1 month at 37 degrees C. As few as 100 infected human peripheral blood mononuclear cells (PBMC) per blood spot could be detected using a single-step RT-PCR reaction and ethidium bromide detection. MV RNA was also detected in dried blood spots obtained from rhesus macaques after challenge with wild-type MV. In the rhesus samples, the single-step RT-PCR reaction could detect approximately 10(3) TCID(50) per blood spot, while nested PCR detected 3 TCID(50) per blood spot. The results of this laboratory-based study suggest that the use of dried blood spots stored on filter has the potential to improve virologic surveillance for MV in some areas, and they emphasize the need for continued testing under field conditions.

Animals↗

PubMed2007

An assessment of the compliance with good pharmacy practice in an urban and rural district in Sri Lanka.

PURPOSE: To evaluate the compliance of private pharmacies to good pharmacy practice (GPP) in an urban and rural district in Sri Lanka and identify deficiencies with a view to improving supply of safe and effective drugs to consumers. METHODS: Lot quality assurance sampling (LQAS) method was used to determine the number of pharmacies that need to be studied and the threshold limit of defective elements. An inspection of 20 pharmacies in the urban and all 18 pharmacies in the rural district was carried out using a structured checklist. Compliance to seven subsystems of GPP was studied. RESULTS: Storage of drugs, maintenance of cold chain, dispensing and documentation were comprehensively substandard in both districts. Individual items of supervision in registration, physical environment and order of the pharmacy were also found to be substandard in both districts. CONCLUSION: This study shows that the LQAS method can be used to identify inadequate pharmacy services in the community as a whole. There was poor compliance to GPP by the private pharmacies in both districts. There are concerns about the quality of drugs and the safety of private pharmacy services to the community. Some of the deficiencies could be easily corrected by educating the pharmacists and authorised officers, and more effective and streamlined supervision.

Clinical Competence↗

PubMed1995

Public health implications of emerging vaccine technologies.

The field of public health and medicine stands to benefit immensely from the emerging vaccine technologies and improved application of existing technologies. Technological advances may promote: (1) greater flexibility and simplicity in the design and operation of immunization campaigns or ongoing prevention programs, including reduction in number of vaccine doses, cold chain elimination, slow-release/prolonged antigenic stimulation, reduced cost and hazard and increased ease of administration through noninvasive, oral delivery systems, greater population levels of immunization and health; (2) the development of documents by FDA, WHO, and other regulatory authorities and groups, to assist the manufacturer in the appropriate manufacturing, preclinical, and clinical development of these new vaccines; (3) a greater array of vaccines to protect the civilian and military populations; (4) increased vaccine potency; (5) vaccines eliciting mucosal immunity, cytotoxic T cells, and/or neutralizing antibody. At the end of the 20th century there remain many unconquered pathogens and noninfectious indications for which medical science suggests that vaccines could be effective. New technologies may provide the best hope to address this wide array of public health needs.

Humans↗

PubMed1992

Anaplasmosis in Uganda. I. Use of dried blood on filter papers and serum samples for serodiagnosis of anaplasmosis--a comparative study.

The suitability of blood collected on filter papers in comparison with corresponding conventional serum samples in the diagnosis of bovine anaplasmosis was studied using the complement fixation test, DOT-ELISA, Western immunoblot and rapid card agglutination test. Dried blood on Whatman filter paper no. 1 was eluted in PBS 0.05% Tween 20 giving an initial dilution of 1:10. The reactivity of the eluted samples in both DOT-ELISA and Western immunoblotting were similar to those obtained with the corresponding straight serum sample dilutions. Filter paper samples gave lower reactivity in the remaining tests when compared with corresponding serum samples. There was no significant difference in the reactivity between the eluates from filter papers stored at temperatures ranging between 15.5 and 24 degrees C and those kept refrigerated. Storage at 15.5 to 24 degrees C did not significantly affect reactivity for up to six months. Eluates from filter papers stored for six months at 15.5 to 24 degrees C continued to give similar reactivity as those from freshly prepared filter papers in both DOT-ELISA and Western blot, and in the rapid card agglutination test. It is concluded that collecting blood on filter papers is a suitable technique for large scale seroepidemiological studies on anaplasmosis and offers many advantages in developing countries where transport and cold chain facilities are a major constraint.

Agglutination Tests↗

PubMed2000

Staff awareness of oral polio vaccine vial monitor in Chandigarh.

This study highlights the awareness of pulse polio centre staff about polio vaccine vial monitor (VVM) during a National Immunization Day in Chandigarh. Out of the 79 staff members interviewed, only 53 (67%) had ever heard of the VVM and were further interviewed. Fifty (94.4%) staff members were aware that VVM is present on vaccine itself and majority (79.2%) told that it is the inner square with outer circle. Only half were aware of its function and 71.7% knew how to read it. It was observed that awareness among health staff [Health worker (F)/ANM] and volunteers was very poor. There is a need for effective training of staff before subsequent PPI to maintain an effective cold chain.

Awareness↗

PubMed2004

Protective effect of BCG among children vaccinated under universal immunization programme.

A case-control study was conducted to estimate the protective effect of BCG vaccination against tuberculosis among children. The children with suspicion of tuberculosis (TB) attending two hospitals in Bangalore city were registered into the study and subjected to detailed clinical examination and investigations. The presence of BCG scar was taken as evidence of vaccination. Modified Stegen-Jones scoring method was adopted for diagnosing TB. The hospital children with score of 7 were considered as TB cases. Children residing in the neighbourhood of cases were similarly investigated and those scoring 4 were labeled as controls. A total of 118 age-sex matched case-control pairs were identified and final analysis was confined to 113 cases and 109 controls after excluding children with doubtful BCG scar. A low protective effect of BCG vaccination at 31% (not significant, statistically) was observed against TB - all forms combined, among children vaccinated as under Universal Immunization Programme. Though the protective efficacy against extra-pulmonary TB was observed to be higher than for pulmonary TB, it was also not significant, statistically. It will be appropriate to conduct further studies on protection rendered by BCG vaccination against tuberculous meningitis and other severe forms of TB. Besides, the quality of vaccination programme including cold chain maintenance also needs to be evaluated.

Adolescent↗

PubMed1984

Poliomyelitis outbreak in South Africa, 1982. II. Laboratory and vaccine aspects.

Between May and September 1982 an extensive epidemic of poliomyelitis occurred in Gazankulu in the north-eastern region of South Africa, with a total of 260 paralysed cases and 42 deaths. A three-part study was instituted, the first of which established the aetiological agent of the epidemic to be poliovirus type 1. This was determined initially by serology and later by isolation of the virus, chiefly from stool specimens. The potency of the trivalent oral polio vaccine manufactured at the National Institute for Virology, was evaluated in the second study by in vitro potency testing of samples recalled from the epidemic areas and also in vivo by determining the serological response of seronegative children immunized with fresh vaccine. Nearly half of the vaccine samples withdrawn from the field had sub-optimal titres whereas fresh vaccine produced a very satisfactory serological response. In order to plan immunization rationally, the third study, namely the determination of the immune status of the various populations throughout the country was instituted. This involved both serology, using a neutralization test on randomly collected sera and also an analysis of patient history and health card documentation. With the exception of the urban black area (Soweto), which had high levels of immunity both serologically (75%) and on history, other areas examined had poorer levels of immunity of approximately 52% on serological testing and 57% on history. It is clear that the epidemic was multifactorial in origin, with fall-offs in the level of immunization and evidence of breaks in the cold chain being the major factors.

Antibodies, Viral↗

PubMed1991

Epidemiology of measles in the Cameroons between 1984 and 1986: comparison of the effectiveness of different serological methods in rural regions.

Epidemiological studies were carried out in Yaoundé and in Ngaoundéré from 1984 to 1986, in an attempt to develop adequate methods of collecting blood from small children and of diagnosing measles appropriate to conditions in the field. Alternative methods were necessary since classical methods used in modern laboratories are unsuitable in rural regions. Each study was carried out on a representative sample of 6- to 36-months-old infected children seen at consultation. This group was chosen because it suffers the highest mortality rate. The blood was obtained by digital puncture on blotting paper because venepuncture required sterile equipment and also the establishment of a cold chain for transporting the samples to the laboratory. The first criteria examined were the relative titers of sera taken by finger prick. Four serological techniques were used: indirect immunofluorescence (IIF), indirect immunoperoxidase (IIP), hemagglutination inhibition (HAI) and ELISA. Antimeasles antibodies were detected in 12% of infected children using IIF and in 18% using IIP. When sera were examined by HAI the percentage of positives was 54% and by ELISA 75%. These results clearly indicate that ELISA is the most effective and practical technique for diagnosing measles under field conditions.

Antibodies, Viral↗

PubMed1996

Bacterial ghosts: non-living candidate vaccines.

Expression of cloned PhiX174 gene E in bacteria results in lysis of bacteria. It is unique among phage lysis systems as it introduces a transmembrane tunnel structure through the cell envelope complex of Gram-negative bacteria. The resulting bacterial ghosts have intact envelope structures devoid of cytoplasmic contents. E-mediated lysis has been achieved in a variety of Gram-negative bacteria including Escherichia coli, Salmonella typhimurium, Vibrio cholerae, Klebsiella pneumoniae, and Actinobacillus pleuropneumoniae. Such ghosts, derived from human or animal pathogens, have been proposed as non-living candidate vaccines and represent an alternative to heat or chemically inactivated bacteria. In 'recombinant ghosts', foreign proteins (e.g., viral proteins) are inserted into the inner membrane via specific N-, or C-, or N- and C-terminal anchor sequences prior to lysis. Relevant advantages of (recombinant) bacterial ghosts as immunogens include: (i) inactivation procedures that denature relevant immunogenic determinants are not employed in the production of ghosts used as vaccines or as carriers of relevant antigens; (ii) the recombinant proteins are inserted into a highly immune stimulatory environment; (iii) there is no size limitation of the foreign protein moieties: multiple antigenic determinants can be presented simultaneously; (iv) bacterial ghosts can be produced inexpensively in large quantities; (v) (recombinant) ghosts are stable for long periods of time and do not require the cold chain storage system. Intraperitoneal, subcutaneous or intramuscular applications of recombinant ghosts in experimental animals induced specific humoral and cellular immune responses against bacterial and viral components. Initial aerosol vaccinations of swine with ghosts from Actinobacillus pleuropneumoniae showed that protective immunity can be established by this route of application and that the well-preserved surface structures of ghosts obtained by E-mediated lysis are able to target the mucosal immune system.

Animals↗

PubMed1988

Stability of oral polio vaccine at different temperatures.

The stability of five batches of oral polio vaccine stored at -20, 4-8, 22 and 36 degrees C for 7, 14 and 21 days was studied. The virus titrations were performed by the standard macro-method. There was little loss in virus titre when samples were kept at -20 and 4-8 degrees C for 21 days, whereas the samples exposed to 36 degrees C for 21 days showed almost complete loss in virus titre. The average loss in virus titre in a year (log TCID50) was 0.47 at -20 degrees C and 0.65 at 4-8 degrees C when various samples were stored at these temperatures. At 22 degrees C the average loss in virus titre after 21 days was about 1.50. The samples subjected to ten cycles of freezing and thawing did not show any loss in virus titre. Likewise there was not much loss in virus titre in three samples stored at 4-8 degrees C for a year. Oral polio vaccine stabilized with magnesium chloride is quite a stable vaccine and maintenance of a proper cold chain is recommended for the delivery of a potent vaccine in countries with high ambient temperature.

Drug Stability↗