The selection pressure analysis of chicken anemia virus structural protein gene VP1.

Chicken anemia virus (CAV) is the pathogen of chicken infectious anemia. To clarify the driving force in CAV evolution, we have detected positive selection in the structural protein gene VP1 by using maximum-likelihood models. Strong evidence was found that VP1 proteins were subject to the high rates of positive selection, and eight sites were identified to be under positive selection using the Bayes Empirical Bayesian method. Interestingly, four selected sites (amino acids 75, 125, 141, and 144) might be responsible for the attenuation exhibited. One selected site (amino acid 287) was connected with the virulence of CAV. This study provided some implication for the evolution of CAV, development of vaccines, and investigation into the structural and functional profiles of the VP1 protein.