To determine whether the less-developed T cell repertoires involved in the immune responses to neonatal vaccination are ‘locked-in’ to secondary responses to infection, we examined the clonotypic composition of gB-8p-specific TCRβ repertoires involved in secondary CD8+ T cell responses to HSV-1 infection in adult mice that had been previously vaccinated with VACV-gB either as neonates or as adults. The gene discussed is CD8A; the disease is infection.