The results from this study support previous human and animal studies on MDD that have uncovered genes centered around a stress-response cascade involving the activator protein 1 (AP-1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κβ).30AP-1 is a gene that codes for a transcription factor that regulates gene expression in response to cytokines as well as environmental stress and bacterial and viral infections. The gene discussed is FOS; the disease is viral infectious disease.