Effect of Sex on Newcastle Disease Virus (NDV) Titer after Infection in Chickens

Many host genetic factors determine resistance to infection. In the current study, we sought to determine whether sex-associated resistance to Newcastle disease virus (NDV) infection exists in chickens by utilizing two genetically distinct inbred chicken lines, Fayoumi and Leghorn, and one genetically diverse commercial bird layer line, Hy-Line Brown. Birds were under constant heat exposure (35C, 65% humidity) starting from two weeks of age and were challenged with NDV at 3 weeks of age. Viral titers from tears at 2 and 6 DPI and antibody response to NDV in serum at 10 DPI were measured. Due to significant effects of genetic line, data were analyzed for each genetic line. There was a significant difference between sexes in viral titer at 6DPI in Fayoumi with females having lower viral titer mean. There was no significant difference between sexes in viral titer at either time point for Leghorns. There was a significant difference between males and females in viral titer at both time points for the Hy-Line birds with the females having lower viral titer. This result indicates greater anti-viral response to NDV in female than male chickens. No significant difference was observed at 10 DPI in antibody titer between the sexes in any genetic lines. The effect of sex on NDV titer may be due to the location of Type 1 interferon genes on the Z sex chromosome. Further analysis into differential gene expression between the sexes for genes involved in immunity may elucidate the underlying mechanism affecting NDV resistance.

Support: USAID Feed the Future Innovation Lab for Genomics to Improve Poultry, and Hy-Line International.