19 Early Events in Human Herpesvirus Infection of Cells

Abstract

Herpesviruses are large, highly complex enveloped viruses containing linear double-stranded DNA. Following primary infection, which is frequently inapparent, the intact viral genome persists in host cells for the life of the individual. Since the presence of the viral genome does not significantly impair normal cellular functions, herpesvirus latent infections are largely asymptomatic. Latently infected cells also escape destruction by the immune system, in part because few viral proteins that can be recognized and targeted by the immune system are produced during latency. In addition, some herpesviruses have evolved specific strategies that interfere with immune recognition. Many, if not all, latent herpesvirus infections are interrupted by periods of reactivation induced by trauma, stress, infection, immunosuppression, or other processes. With reactivation, herpesviruses enter the productive phase of the viral life cycle, and viral particles are produced. Virus production leads to death of the host cell. Furthermore, virus-producing cells are targeted for destruction by the immune system. Destruction of cells and immune processes lead to inflammation with its associated symptomatology.

Most of the herpesviruses are ubiquitous pathogens. For example, more than 90% of individuals worldwide have been exposed to herpes simplex virus type 1 (HSV-1) and Epstein-Barr virus (EBV) by adulthood. The other human herpesviruses, which include cytomegalovirus (HCMV), varicella zoster virus (VZV), herpes simplex virus type 2 (HSV-2), and herpesviruses 6, 7, and 8 (or 6A, 7, and 6B) are also quite prevalent in most populations. Herpesviruses have been found in many species. Marek’s disease in chickens, Aujeszky’s disease in pigs, and...