Genetic and phenotypic correlations between immune response to Escherichia coli and to Newcastle disease virus vaccines.

Genetic and phenotypic variation and covariation in immune response to inactivated Newcastle disease virus (NDV) vaccine and to Escherichia coli vaccine were studied in commercial poultry strains. Within any given experiment there was no tendency for individual birds to respond in a correlated manner to NDV and E. coli vaccines. There were highly significant differences between sire families in immune response to NDV vaccine (57 sire families) and to E. coli vaccine (35 sire families). Heritabilities of immune response levels to NDV and to E. coli were .41 and .25, respectively. In both cases, additive genetic standard deviations were slightly over 1.0 titer unit. The correlation between sire-family means for response to NDV and sire-family means for response to E. coli (35 sire families) was .077 and statistically nonsignificant. Thus, the data provide evidence for the presence of significant genetic variation in immune response with respect to two endemic disease antigens, but they provide no evidence for a genetic correlation in response to the two antigens.

Immune response to Newcastle disease virus vaccine, fowl-pox vaccine, and Escherichia coli vaccine in Bedouin and White Leghorn chickens.

Immune response to Newcastle disease virus (NDV) vaccine, fowl pox, and E. coli vaccine was compared in the native Bedouin fowl of the Sinai desert, in a commercial Leghorn layer strain, and in the reciprocal crosses between them. Differences were not found in antibody titer levels to attenuated or inactivated NDV vaccines, in the proportion of birds showing post-vaccination immunity to fowl pox, or in the kinetics of postvaccination NDV titer levels. Rate of development of titer to Escherichia coli from day 1 to day 4, however, was significantly more rapid in Bedouin chicks than in the purebred Leghorn or the reciprocal crosses.

Biochemical changes in fowl serum during infection with strains of Newcastle disease virus of differing virulence. Changes in serum proteins, uric acid, lipids and electrolytes.

Chickens aged five to six weeks were inoculated with three strains of Newcastle disease virus of differing pathogenicity. The serum level of the metabolites: total protein, albumin, globulin, uric acid, total lipids, cholesterol and electrolytes: calcium, magnesium, sodium and potassium were determined. The changes in serum levels of metabolites were as follows: velogenic infection was accompanied by decrease in total protein and albumin, reduction of lipids and cholesterol and increase in uric acid. No significant changes were found in the values of these metabolites in the serum of chickens infected with mesogenic strain. Lentogenic strain caused elevation of uric acid and cholesterol. All three strains caused decrease of the level of potassium in serum.

Spray vaccination of chickens with an experimental vaccine against Newcastle disease.

Chickens, of various age groups, were vaccinated against Newcastle disease by spray vaccination with an experimental vaccine, designated V5K7E1. Aerosol spraying of 3-days-old chicks having a high titre of maternal antibodies failed to induce any obvious stimulation of haemagglutination-inhibiting antibodies. The chicks, when challenged 2 and 3 weeks after vaccination, were fully protected, but protection was inadequate when they were challenged 4 to 7 weeks after vaccination. Spray vaccination of 1-day-old specific-pathogen-free chicks resulted in the presence of antibodies at 7, 14 and 21 days. Subsequently the levels of antibodies declined progressively. The chicks resisted challenge up to 42 days after vaccination. Maternally immune chicks spray - vaccinated for the first time at 14 days showed a significant increase in antibodies and remained healthy when challenged at 10 weeks of age. Booster spray vaccination at 21 days of age subsequent to primary spray vaccination at 3 days of age, induced an anamnestic rise in antibody titre that persisted at protective levels for at least 66 days. Similarly, spray vaccination at 28 days, following administration of vaccine in the drinking water at 14 days, gave rise to high antibody titres which persisted for at least 70 days. In field trials, spray vaccination at the age of 3 days or 14 days provoked little or no apparent respiratory disturbance and was followed by an average mortality of 0.9% and 1.4% respectively.

Familial differences in antibody response of broiler chickens to vaccination with attenuated and inactivated Newcastle disease virus vaccine.

Genetic differences in immune response to Newcastle disease virus (NDV) were studied in 4-week-old broilers, vaccinated with attenuated (live) or inactivated NDV. The experiment included 370 chicks from two farms distributed among 22 sire families and 60 dam families. Results in chicks from both farms were similar. Survival after challenge was closely related to titer level. The genetic correlation between day-7 and day-12 titers (attenuated virus) was 1.0. Significant differences were found between sire families in both sorts of vaccinations. Heritabilities based on the sire variance components for attenuated and inactivated virus vaccinations were respectively 0.31 and 0.60. The genetic correlation between them was 0.49. Nevertheless, it is concluded that selection for response to NDV based on inactivated virus may be most effective in improving response to attenuated NDV vaccinations.

Development of a new vaccine against turkey meningo-encephalitis using a virus passaged through the Japanese quail (Coturnix coturnix japonica).

Turkey meningo-encephalitis virus could be adapted to the Japanese quail by intra-cerebral inoculation. After 4 passages the virus was found to be less pathogenic for the turkey. Further attenuation could be achieved by growing the virus in Japanese quail kidney cell cultures for 11 passages. This attenuated virus was used for the preparation of a live vaccine against turkey meningo-encephalitis. The safety and efficacy of the vaccine was shown in laboratory and field experiments.

Biochemical changes in chicken serum during infection with strains of Newcastle disease virus of differing virulence. I. Enzyme study.

Chickens aged 5-6 weeks were inoculated with 3 strains of Newcastle disease virus of differing pathogenicity. The levels of the enzymes lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), cholinesterase (ChE), alkaline and acid phosphatase (ALP and AcP), glutamate-oxaloacetate and glutamate-pyruvate transaminases (GOT and GPT) in serum were measured. Significant decreases in the levels of ChE and ALP were found in chickens infected with high doses of a velogenic strain of virus. The levels of LDH, ICDH and GOT were elevated in these chickens, but the levels of AcP and GPT were unchanged. ALP levels were slightly decreased and LDH levels were slightly elevated in chickens that were inoculated with a mesogenic strain. No significant changes in enzyme levels were found in chickens infected with lentogenic virus. Changes in enzyme levels were found to be correlated with the clinical findings in the infected chicks.

Turkey meningo-encephalitis: pathogenic and immunological aspects of the infection.

The distribution of turkey meningo-encephalitis virus in infected birds and the development of immunity were studied. The turkey meningo-encephalitis virus was present in the blood as early as 24 h after experimental inoculation, and persisted for 5-8 d. Antibodies could be detected about the 5th d. A good correlation was found between haemagglutinin-inhibiting and virus-neutralizing antibodies. The virus could not be reisolated from any blood or organ sample collected after the 14th d and no sign of latent infection or carrier state could be found. The infection did not spread from the inoculated turkeys to control un inoculated birds in close contact. The possible existence of a natural reservoir and an arthropod vector of this virus is discussed.