No abstract

Twenty-four-week-old white leghorn layers were inoculated subcutaneously with a killed Newcastle-infectious bronchitis (Massachusetts type) virus (MIBV) vaccine. The birds were challenged 194 days later intraocularly with Arkansas strain of infectious bronchitis virus (AIBV). The challenged hens laid significantly (P less than 0.005) fewer eggs than the unchallenged layers, and the eggs laid by the challenged groups weighed significantly less (P less than 0.001) than those laid by the unchallenged groups. Further, the internal quality (Haugh units) and shell quality of eggs laid by the challenged hens were significantly (P less than 0.005) inferior to the quality of eggs from unchallenged hens, and the challenged hens laid more soft-shelled, misshapen, and small-sized eggs than the unchallenged hens. The Arkansas serum hemagglutination-inhibition (AIBV-HI) titers of challenged birds increased continuously through 29 days post-challenge. The MIBV hemagglutination-inhibition (MIBV-HI) titers of killed-MIBV-vaccinated birds decreased during the same period. The study indicates that killed MIBV vaccine offered no protection to birds exposed to AIBV. The same vaccine was quite effective against a homologous (MIBV) virus challenge.

No abstract

A comparison was made of absolute numbers of peripheral blood B and T lymphocytes, as defined by the anti-bursal and anti-thymus sera, in chickens infected with infectious bursal disease virus at one day and 3 weeks of age by age-matched controls. Birds were evaluated sequentially at weekly intervals for a period of 8 weeks postinfection. The severity of depressions of B-lymphocyte numbers was found to be age-dependent: the birds infected at one day of age showed a more severe depletion than those infected at 3 weeks of age. The T-lymphocyte numbers were less markedly affected in infected chickens of either age group.