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Biomedical subjects

R P Hanson

Publications and source records attributed to R P Hanson.

At least 19 recordsLinked to original sources
PubMed1990

Experimental avian PMV-2 infection in a domesticated wild host: daily behavior and effect on activity levels.

Paramyxovirus type 2 (PMV-2) isolated from wild birds is often considered non-pathogenic, but nothing is known about its effects on overall behavior and fitness of free-flying birds. Domestically bred, African cut-throat finches (Amadina fasciata), a species from which PMV-2 has been isolated in the wild, were inoculated with a Central American field strain of PMV-2. Patterns of behavior were examined before and after viral challenge to quantify inapparent, sublethal effects of the disease. Infected birds demonstrated a significant decrease in activity (P = 0.01) followed by an apparent recovery period. Antibody titers confirmed infection in inoculated birds and indicated that sentinel birds did not become infected.

Analysis of Variance↗
PubMed1989

In vivo interference by Newcastle disease virus in chickens, the natural host of the virus.

Homologous and heterologous viral interference is a common occurrence that has been well studied in vitro. In the present study, homologous viral interference between the LaSota and NYP strains of Newcastle disease virus (NDV) was studied in vivo in chickens, the natural host for NDV. The LaSota strain is avirulent and widely used as a vaccine in poultry industry, while the NYP strain is highly virulent and causes acute disease and death in chickens within four to six days after infection. Chickens generally became resistant to NYP strain challenge 12 hours after intranasal or intratracheal inoculation with LaSota strain virus. The resistance was manifested by reduction in chicken morbidity and mortality, decrease in virus replication in the chicken respiratory tract (p less than 0.05), and inhibition of NYP strain induced gross and microscopic lesions. Interferon was first detected in the chicken respiratory tract and blood at 3 to 6 hours; it peaked at 12 to 24 hours and was maintained for 48 hours after viral inoculation, indicating that interferon induction might be one possible mechanism of the interference between the two strains. This study suggests a role for viral interference in vaccination against virulent viruses.

Animals↗
PubMed1988

Koch is dead.

Although the foundation of Koch's postulates, that "if an agent is the cause of disease in one individual it should be capable of causing disease in a second individual," is basically sound, the ritual that has evolved into present day experimental studies has obscured almost completely what occurs in natural processes outside the laboratory. Through a series of examples, it is emphasized that just bringing the host and the parasite together is not enough, but that the circumstances under which this is done is equally important. These circumstances include: the prior history of the host; the host's behavioral patterns, environmental conditioning, and disease history; the circumstances of exposure; and the environmental factors related to the host and the parasite. Of equal importance is the individual variation (genetic, physiologic, immunologic, etc.) of the host and the individual variation (strains, immunogenicity, pathogenicity, virulence, etc.) of the parasite. Because the rigor of the present day "scientific method" demands clearcut and reproducible results and investigations require predictable performance of the parasite in an evenly maintained host that is in a highly constrained environment, we should not wonder why we cannot produce the events of nature. If we are going to understand diseases of wildlife, we must consider the genetic heterogenicity of the host and parasite population, and recognize the complexity of the environment in which both exist. Koch's postulates, in the narrow sense, will help us to identify parasitisms but will not provide us with an understanding of information about diseases in wildlife; the real significance of these parasitisms to the health of the individual and to the size of the population.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Genotypic and phenotypic variation of biotypes coexisting in the Hickman strain of Newcastle disease virus.

Many Newcastle disease virus strains are composed of several biotypes which coexist in the wild and in laboratory cultures. We have studied some of the phenotypic and genotypic properties of 6 virus clones from the coexisting biotypes of the Hickman strain of Newcastle disease virus. These clones were readily distinguishable from the parent virus strain and from each other by their RNA fingerprints. Fingerprints of the most virulent clones (Hi/LC, Hi/MC, and Hi/LR) contained 61% to 77% of the oligoribonucleotides present in the fingerprint of the Hickman parent strain. None of the clones killed chickens as rapidly as did the parent strain, although some clones killed embryonating eggs as rapidly as did the parent strain.

Genotype↗
PubMed1985

Studies on the development of pelleted Newcastle disease virus (NDV) vaccine.

White leghorn chickens (7-10 weeks old) were orally infused with varied doses of lentogenic and mesogenic strains of Newcastle disease virus. The antibody response of the chickens was monitored by haemagglutination inhibition tests weekly for 4 weeks postinfusion. A high dose of virus (10(9) EID50) was necessary to induce a serological response typical of chickens that resist challenge. Sera from chickens infused with low doses (10(5) EID50) of the virus only showed marginal haemagglutination inhibiting activity. Trypsin levels as high as 0.35 mg ml-1 were detected from duodenal secretions and are assumed to be responsible in part for viral inactivation. Fasting (no food and water) the chickens beyond 12 h did not appear to increase antibody response to low titre virus.

Animals↗
PubMed1982

Newcastle disease virus in waterfowl in wisconsin.

Newcastle disease virus was isolated from the cloaca of 1-5% of live-trapped waterfowl in Wisconsin in the fall from 1978-1980. Antibody to NDV was detected in 8% of the birds tested, with no apparent difference between sex and age classes. Experimental infection resulted in persistence of virus shedding for months after exposure. Lack of detectable antibody in some of the experimentally infected birds suggests that reported antibody prevalence may not be indicative of the true prevalence of the infection. Isolation of NDV for the last 9 years as well as the detection of antibody in waterfowl over 25 years ago, suggests a well-adapted host-parasite relationship. Experimental evidence of virus persistence in individual mallards (Anas platyrhynchos) provides a mechanism for maintenance of the virus in the wild population.

Animal Population Groups↗
PubMed1980

Experimental infection and serologic survey for selected paramyxoviruses in red-winged blackbirds (Agelaius phoeniceus).

Red-winged blackbirds (Agelaius phoeniceus) were experimentally exposed to three avian paramyxoviruses: turkey parainfluenza virus, Yucaipa virus, and two strains of Newcastle disease virus. Aerosol exposure resulted in infection but exposure in food or drinking water rarely or never did. Tracheal swabs contained virus for up to eight days post exposure, cloacal swabs were negative. Transmission to contact birds occurred infrequently. Antibody response was of low titer and short duration. No hemagglutination inhibition activity against these viruses was found in 387 sera collected from red-winged blackbirds and tricolored blackbirds (Agelaius tricolor) trapped in six states.

Animals↗
PubMed1979

Hepatitis-B surface antigen and antibody: prevalence and persistence in institutionalized and noninstitutionalized persons.

A total of 426 persons were studied in an attempt to more clearly define the high prevalence of hepatitis-B surface antigen (HBsAg) seen among institutionalized persons. HBsAg was found in 63.4 percent of the children and young adults with Down's syndrome (DS) at the Central Wisconsin Center (CWC) and in 45.5 percent of those at the Northern Wisconsin Center (NWC). Significantly more subjects with DS had hepatitis-B antigenemia than age- and sex-matched non-DS institutionalized subjects. Antibody (anti-HBs) to HBsAg was found in 19.5 percent of the DS subjects at CWC and in 38.6 percent of those at NWC. The prevalence of anti-HBs was similar among DS and non-DS institutionalized subjects. None of the noninstitutionalized subjects had HBsAg in their serums and their anti-HBs prevalence was low (2.1 percent). HBsAg was found to persist for at least 10 years in both DS and non-DS institutionalized subjects. However, persistence occurred more frequently among DS subjects. Anti-HBs persisted at least 10 years among non-DS subjects, but DS subjects tended to lose antibody sooner. The study findings indicated that the high prevalence of HBsAg seen in institutionalized DS subjects at CWC and NWC were not related to the age of the subject at admission nor to the duration of institutionalization.

Adolescent↗
PubMed1978

Membrane-free scrapie activity.

Determinations of scrapie activity in subcellular fractions from infected hamster brains through the asymptomatic and symptomatic course of infection revealed the presence of substantial amounts of scrapie infectivity in the 100,000 X g supernatant fractions, indicating that association with physically discernible membrane structures is not necessary for the transmission of the scrapie agent. An increase of scrapie infectivity in the 100,000 X g supernatant fractions after vigorous homogenization of infected membrane-rich fractions suggests that the agent is identical in membrane-rich and 100,000 X g supernatant fractions.

Animals↗
PubMed1977

Immunogenicity of Australian lentogenic strains of Newcastle disease virus.

Seven-week-old chickens vaccinated oronasally with V4 and CT strains of Australian lentogenic strains of NDV were immune to intramuscular challenge with Herts 33 and Texas GB strains of virulent NDV. Vaccination of 1- and 3-week-old chickens with V4 strain by oronasal, conjunctival and drinking water routes using various doses of virus demonstrated that chickens were immune to oronasal challenge with Fontana 1083 strain of virulent NDV except where low doses of vaccine virus were administered. One 6- and 36-week-old chickens vaccinated oronasally with CT strain of virus remained immune to oronasal challenge with Fontana 1083 strain for 9 weeks after vaccination. Immunity was waning at 16 weeks after a single vaccination with CT strain.

Animals↗
PubMed1977

A study of Cytomegalovirus, Epstein-Barr virus and Herpesvirus hominis (types 1 and 2) antibody in institutionalized and non-institutionalized children.

In an attempt to demonstrate differences in antibody prevalence between free-living and institutionalized children, antibodies to Cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Herpesvirus hominis (HVH), types 1 and 2, were assayed in 123 children. The children comprised three groups consisting of 41 institutionalized patients with Down's syndrome (all non-disjunctive trisomy-G karyotype and equal numbers of age-, sex-, and race-matched non-mongoloid institutionalized subjects and non-institutionalized normal controls. CMV antibody titer values were statistically similar in the three groups. However, fewer mongoloids (21.9%) were seropositive than other institutionalized retardates (39.0%) and normal control subjects (43.9%). Antibody titer values to EBV were also similar; however, in comparison to the other groups, significantly more mongoloids were seropositive at younger ages. More mongoloids were seropositive to HVH-1 and had higher antibody titers than the other two groups. Antibody to HVH-2 was more prevalent in institutionalized subjects, 85.4% in mongoloids and 65.8% in other institutionalized retardates, than in normal non-institutionalized children (26.8%).

Adolescent↗
PubMed1976

Simulated natural infection of chickens with Australian lentogenic newcastle disease virus and subsequent challenge with virulent virus.

A total of 291 eight-week-old chickens were exposed to chickens infected with either of two Australian lentogenic strains (V4 and AVL NDV-1) of Newcastle disease virus (NDV). At 3 weeks after exposure, all chickens exposed to V4 infected chickens had developed haemagglutination-inhibition (HI) antibody. All chickens exposed to AVL NDV-1 virus infected chickens had developed HI antibody 5 weeks later. This sudden late appearance of HI antibody, to titres higher than those observed with V4 chickens, was explained by V4 virus being introduced to the AVL NDV-1 group of chickens. When groups of these chickens were challenged with Roakin virus (mesogenic NDV) at 3 weeks and Fontana 1083 virus (viscerotropic velogenic NDV) and Texas GB virus (neutrotropic NDV) at 3, 5, 10 and 21 weeks only three chickens developed clinical illness one of which died. These chickens were one AVL NDV-1 chicken contact challenged with Fontana 1083 virus at 3 weeks, one V4 chicken oronasally challenged with Texas GB virus at 5 weeks and one V4 chicken challenged oronasally with Fontana 1083 virus at 10 weeks. Susceptible non-vaccinated chickens died soon after challenge. Challenge by oronasal infection with 10(7.0) ELD50 of virus or contact with susceptible infected chickens enabled virulent virus to be isolated from most chickens and was accompanied by a large anamnestic increase in serum HI antibody.

Animals↗
PubMed1976

Properties of the scrapie agent-endomembrane complex from hamster brain.

Subcellular fractionation of scrapie-infected hamster brain indicated the association of the scrapie agent with a component of the endomembrane system. Characterization by equilibrium density gradient centrifugation, electron microscopy, and marker enzymes suggested a primary association with rough and smooth endoplasmic reticulum and a possible incorporation into the plasma membrane. DNA polymerase activity demonstrated a direct correlation with regions of scrapie activity from the gradient fractions. A scrapie-related product was detected after (3H)TMP incorporation and analysis on 2.2% polyacrylamide gels. Analysis of nucleic acid species extracted from subcellular fractions resulted in a greater quantity from healthy brain; however, no qualitative distinctions were detected.

Adenosine Triphosphatases↗