Litter in a room which had housed chickens and turkeys actively infected with velogenic viscerotropic Newcastle disease was no longer infectious for susceptible chickens placed there 10 to 14 days later.

Animals↗

PubMedDate not supplied

Antibody response and resistance of turkeys to Newcastle disease vaccine strain LaSota.

Studies were undertaken to determine the influence of repeated revaccination on the immune response in immuno-competent turkeys as measured by humoral antibody and resistance to challenge. Protection was better in turkeys given the LaSota spray vaccine at 4 weeks and 30 days later than in turkeys given one vaccination by spray or intramuscular route or exposed 4 times at 10-day intervals by the aerosol route. The anamnestic response, as measured by the HI tests to revaccination with the same immunogen, was not evident by the 3rd day postrevaccination but was observed on the 7th day. The interval between primary and secondary vaccination was found to be important to a true and optimal anamnestic response. Response was greater, however, in vaccinated turkeys exposed to VVND, a more virulent virus antigenically different from the vaccine strain. Exposure to LaSota vaccine by the intramuscular route gave a poorer HI response than LaSota given by aerosol.

Animals↗

PubMedDate not supplied

In vitro DNA synthesis in lymphocytes from turkeys vaccinated with LaSota, TC, and inactivated Newcastle disease vaccines.

In vitro cultures of peripheral blood lymphocytes from turkeys vaccinated and revaccinated with Newcastle disease (ND) vaccines were stimulated to transformation when exposed to the homologous and heterologous strains of ND virus. The mitogenesis was measured by the uptake of 3H-thymidine into newly synthesized DNA. There was considerable difference in DNA synthesis by lymphocytes drawn 0, 2, 5, and 10 days after vaccination and revaccination with the three vaccines. Stimulation of DNA synthesis, evident as early as the 2nd day, was highest in lymphocytes from turkeys vaccinated or revaccinated with TCND intramuscularly. Stimulation was least in lymphocytes from turkeys vaccinated and revaccinated with LaSota vaccine by aersol. Stimulation was intermediate from an inactivated vaccine given subcutaneously. DNA synthesis was greater with the homologous than with the heterologous strains of NDV. Synthesis was even greater when the same strain was used as a viral suspension in allantoic or cell-culture fluid than the commercial vaccine. The bovine paramyxovirus (PI3) resulted in a minimum DNA synthesis or completely inhibited it. A many-fold (order of magnitude) stimulatory effect was observed when PHA was used as an antigen. The stimulation of DNA synthesis did not parallel the HI antibody response.

Animals↗

PubMedDate not supplied

Hemorrhagic enteritis of turkeys in California: serologic study of hemorrhagic enteritis virus antibody with an enzyme-linked immunosorbent assay.

The incidence of hemorrhagic enteritis (HE) infection in California turkeys was studied by testing 2220 turkey blood samples from 173 flocks for HE virus (HEV) antibody by the enzyme-linked immunosorbent assay (ELISA). Maternal antibody was detected at 1 day of age in all flocks tested, and it vanished after 3 weeks. Acquired HEV antibody appeared at 8 to 10 weeks, and 100% of the meat and breeder turkey flocks were positive after 11 weeks of age. HEV infection occurred earlier in the meat flocks than in the breeder flocks, and it also occurred earlier during summer than during the fall and winter months.

Animals↗

PubMedDate not supplied

Cell-culture virus-neutralization test and enzyme-linked immunosorbent assay for evaluation of immunity in chickens against fowlpox.

Two serological tests--the virus-neutralization (VN) test in chicken embryo fibroblasts (CEF) using a cell-culture-adapted virus, and the enzyme-linked immunosorbent assay (ELISA)--were used for evaluating the immune response in chickens against fowlpox virus. The VN test was conducted in 96-well tissue-culture plates using a fowlpox virus that was adapted to induce cytopathic effects (CPE) in CEF in 48 hr. The ELISA was carried out with an antigen prepared by precipitation of a cell-culture-propagated virus suspension with ammonium sulfate and concentration by centrifugation. A 0.1 M acetate buffer, pH 5, was used as the sensitizing solution for maximum specific binding of the antigen to the microplate plastic well. No antibodies were detected by the VN test in 228 serum samples taken from chickens at irregular intervals between 1 and 39 weeks of age, even though the birds were vaccinated against fowlpox at 13 weeks of age. However, in sera collected 4 weeks after a sample of laying hens was challenged with fowlpox virus, VN titers of 1/10 to 1/40 were detectable. On the other hand, significant antibody reactions were detected by the ELISA on sera from chickens during the growing period, following vaccination and challenge. Although no maternal antibodies were found at 1 week of age, a continuous increase in the mean ELISA titers to fowlpox was demonstrated during the entire experimental period. This study showed that the ELISA was considerably more sensitive and practical than the VN test.

Animals↗

PubMedDate not supplied

Paramyxovirus type 3 (PMV-3) in California turkeys: serologic study of PMV-3 antibody with an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for detecting paramyxovirus type 3 (PMV-3) antibody. This test had a higher sensitivity than the hemagglutination-inhibition test, and no cross-reactivity with various paramyxoviruses or avian pathogens was detected when the sera were tested diluted 1:200. The incidence of PMV-3 infection in California was studied by testing 2037 turkey sera from 174 meat and breeder flocks for the presence of PMV-3 antibody using the ELISA. The age at which the infection occurs was around 5 to 8 weeks for meat flocks and 10 to 12 weeks for breeder flocks. Infection with the PMV-3, as determined serologically, was more frequent than manifested cases of disease, and 95.2% of the flocks aged over 11 weeks had PMV-3 antibody. No typical manifestations of PMV-3 disease (respiratory disease plus drop in egg production) were observed, probably because of the early infection which occurred before laying age.

Animals↗