Modes of protection against infection shared by smallpox vaccine viruses.

2003 OCT 8 - (NewsRx.com & NewsRx.net) -- Researchers report shared modes of protection against poxvirus infection by attenuated and conventional smallpox vaccine viruses.

"The concern about bioterrorism with smallpox has raised the possibility of widespread vaccination, but the greater prevalence of immunocompromised individuals today requires a safer vaccine, and the mechanisms of protection are not well understood. Here we show that, at sufficient doses, the protection provided by both modified vaccinia Ankara and NYVAC replication-deficient vaccinia viruses, safe in immunocompromised animals, was equivalent to that of the licensed Wyeth vaccine strain against a pathogenic vaccinia virus intranasal challenge of mice," scientists writing in the journal Proceedings of the National Academy of Sciences USA report.

"A similar variety and pattern of immune responses were involved in protection induced by modified vaccinia Ankara and Wyeth viruses," stated Igor M. Belyakov and colleagues at the National Institutes of Health in the United States. "For both, antibody was essential to protect against disease, whereas neither effector CD4+ nor CD8+ T cells were necessary or sufficient. However, in the absence of antibody, T cells were necessary and sufficient for survival and recovery. Also, T cells ...