Nutrition and Biochemistry of Survival During Newcastle Disease Virus Infection

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Abstract
Liver size and content of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein and lipids were observed in 580 White Leghorn cockerel chicks one to 7 weeks of age. Comparisons were made of the effects of age and Newcastle disease virus (NDV) infection at 2 levels of virulence. Biochemical changes per gram of liver tissue in infected birds were related to the stage of the disease cycle as follows: Incubation of the virus: Increased liver weight and DNA. RNA was depressed, with no apparent change in protein and lipids. Active involvement of virus: Reduced liver weight. DNA and RNA increased, with no apparent effect of the infection on protein and lipids. Initiation of recovery of the host (19 days post inoculation): No differences between treatments for DNA, RNA, protein and lipids, indicating that metabolic processes of the infected bird had normalized. Total quantities of liver DNA, RNA, protein and lipids were significantly less in the NDV-infected birds as compared with controls. This phenomenon was hypothesized to be a function of body size. Calculations made of a phase of protein metabolism termed “protein efficiency of cellular RNA” were postulated as being part of the defense mechanism. Serum HI antibody titers were highest in birds with the greatest degree of involvement.