AVP and infection: In 2014, Hari and Vyas (2014) detected the methylation level of the arginine vasopressin gene (AVP) in the medial amygdala of the brain tissue of infected male mice and found that after infection, the promoter of host AVP was hypomethylated and the gene expression was increased, resulting in increased secretion of testosterone and eventually leading to the reduction in fear to cat urine odor in infected mice.