Biomedical subjects

K B Platt

Publications and source records attributed to K B Platt.

42 records · Page 3Linked to original sources

PubMed1984

The evaluation of a lectin-agarose based subunit vaccine and complementary diagnostic antigen for Aujeszky's disease (pseudorabies) in the pig.

Eleven out of 25 pigs were immunized with a lectin--agarose based subunit vaccine for Aujeszky's disease (AD). The vaccine was prepared by extracting protective antigens from a non-ionic detergent (Triton-X-100) extract of AD virus-infected PK-la cells with Lens culinaris agglutinin immobilized on agarose beads. Two groups of 3 and 4 pigs received 2 doses of vaccine each containing 426 micrograms of adsorbed protein. Two groups of 2 pigs each received 2 vaccine doses containing either 23 or 33 micrograms of adsorbed protein. All vaccinated pigs survived a nasal challenge of 10(8.5) PFU of virulent AD virus while 13 out of 14 (93%) uninoculated controls died between Days 5 and 9 post challenge. This immunizing preparation qualified as a practical subunit vaccine because pigs were protected with relatively small amounts of protective antigen while at the same time remained free of detectable antibody to a complementary diagnostic antigen. This antigen was obtained in relatively pure form from the maintenance medium of virus-infected cells 4 h post-inoculation. In addition both high and low dose vaccinates failed to produce detectable antibody to at least one other antigen complex. The composition of Lens culinaris agglutinin (LCA) and Ricinus communis agglutinin (RCA)-purified AD viral antigen preparations were also compared by crossed immunoelectrophoretic techniques. Both preparations contained two antigen complexes and two individual antigens in common. Each preparation also contained its own unique antigen complex. The RCA purified antigen preparation also contained small quantities of a single antigen that was not detectable in the LCA antigen preparation.

Adsorption↗

PubMed1983

Pseudorabies: experimental studies in raccoons with different virus strains.

Raccoons (Procyon lotor) were infected by the nasal/oral route with as little as 10(2) plaque forming units (PFU) of pseudorabies virus (PrV). There was no apparent difference in the susceptibility of raccoons to infection with either of two virulent field strains or with the naturally avirulent K strain which has been used in modified live virus vaccines. Each of these three viruses was transmitted by contact to uninfected raccoons. All raccoons that were infected with virulent field strains died; however only two of 11 (18%) raccoons that were infected with the K strain died. One of four raccoons that survived infection with the K strain survived superinfection with virulent virus. This finding was significant because it could be a mechanism by which virulent PrV can be introduced and persist in the raccoon population. The possibility of this event occurring is increasing because of the widespread prevalence of PrV and the use of modified live virus vaccines for controlling clinical pseudorabies in swine. Virus neutralizing activity was found in five of 47 serums collected from raccoons that were trapped in PrV endemic areas. This observation implies that a herpesvirus, possibly PrV, may be present in the wild raccoon population.

Animals↗

PubMed1982

The porcine humoral response to detergent extracted Aujeszky's disease (pseudorabies) virus antigens.

Twenty Aujeszky's disease (AD) virus antigens were demonstrated by crossed immunoelectrophoresis in a Triton-X-100 detergent extract of virus-infected PK-1a cells. Eight of these antigens were shown to be glycosylated based on their ability to be specifically bound by the lectin Ricinus communis agglutinin II. Pigs nasally infected with AD virus showed a significant serum antibody titer to seven of the known glycosylated antigens and to four additional antigens. The antibody titer to these antigens persisted for at least 116 days. Pigs which were vaccinated parenterally with the whole detergent extract survived a nasal challenge of 10(8 . 5) PFU of virulent AD virus. The antibody response of these vaccinated pigs on the day of challenge was essentially identical to the recovery response previously observed in non-vaccinated nasally infected pigs. These results indicate that the optimum components of future AD virus subunit vaccines and their complementary diagnostic reagents should be selected from these 11 antigens.

Animals↗

PubMed1980

Differentiation of vaccine strains and field isolates of pseudorabies (Aujeszky's disease) virus: trypsin sensitivity and mouse virulence markers.

Five cloned virulent North American field isolates and 2 European vaccine strains of pseudorabies (PR) viruses were compared by their sensitivity to trypsin and their virulence for mice. Marked differences in trypsin sensitivity were detected between and among virulent and vaccine PR viruses. These differences were distinct enough to characterize a virus as either sensitive or resistant to trypsin. This test also differentiated 2 virulent viruses which were previously shown to be indistinguishable on the basis of their sensitivity to thermal inactivation. Mouse virulence was evaluated by comparing the mean times-to-death of mice infected with individual viruses. Three distinct levels of virulence were observed. The two vaccine viruses were differentiated from each other and from virulent virus. Mice infected with the vaccine viruses required 23 to 118 hours longer to die than mice which were infected with virulent virus. A significant difference of 5.6 hours (P less than .005) was also detected between mice infected with 2 different field viruses. When viruses were described according to their marker profiles, 5 of 6 possible combinations were revealed. The 2 vaccine viruses could be described by separate profiles and virulent viruses could be described by 1 of 3 profiles.

Animals↗

PubMed1979

Differentiation of vaccine strains and field isolates of pseudorabies (Aujeszky's disease) virus: thermal sensitivity and rabbit virulence markers.

Eleven cloned North American pseudorabies virus (PRV) strains and the European vaccine strains K and BUK were characterized by their thermal sensitivity and rabbit virulence markers. Heat sensitivity of the strains and isolates ranged from the highly heat resistant strain K, to the extremely heat labile strain BUK and isolate Be. The inactivation curves of each virus were transformed to the logarithmic scale and their standardized slopes and predicted virus survival values at 30 minutes were plotted against each other. The result was a distribution of points that represented a thermal sensitivity spectrum (TSS). Virus strains were subsequently categorized into 1 of 3 groups according to their position in the TSS. Viruses were also categorized into three groups according to their ability to clinically infect rabbits, their ability to produce pruritus and the time required to kill. When individual strains were described according to their marker profiles, 5 of 9 possible marker combinations were revealed. The 2 vaccine strains were each described by separate profiles. Virulent field isolates were characterized by 1 of 3 different profiles.

Animals↗

PubMed1976

Evaluation of the indirect fluorescent antibody test for detecting Trypanosoma vivax in South American cattle.

The indirect fluorescent antibody test (IFAT) as used in Africa for detecting bovine trypanosomiasis was adapted for use in South America and evaluated. Antigen consisted of Trypanosoma vivax laden bovine blood fixed in a 60 : 40 : : acetone : methanol solution. The test detected initial titres of 1 : 50 and 1 : 100 at an average of 13.1 and 15.9 days post parasitaemia (PP). Maximum titres as high as 1 : 400 developed in eight calves at an average of 23.4 days PP. In another calf, 109 days PP were required. Efficacy in detecting sero-positive calves throughout the course of infection was 81.1 and 96.4 per cent at serum dilutions of 1 : 100 and 1 : 50 respectively. No false positive reactions occurred when sera from 36 haemoparasite-free calves were tested. Cross reactivity did not occur when sera from calves singularly infected with Trypanosoma theileri, T evansi, Anaplasma marginale, Babesia argentina, B bigemina and Eperythrozoon spp were similarly tested in the IFAT. No significant differences were found in IFAT results of surveys in which both conventional serum samples and sera eluted from dried blood samples on filter paper from the same calf were used.

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