Macaque model used to assess safety of nonreplicating candidate RSV vaccines.

2003 JAN 8 - (NewsRx.com & NewsRx.net) -- A study in macaques showed that "formalin-inactivated respiratory syncytial virus (RSV) [induced] interleukin-13-associated hypersensitivity to subsequent RSV infection."

R.L. Deswart and colleagues, Erasmus MC, Institute of Virology, Netherlands, pointed out that RSV "is a major cause of severe respiratory disease in infants and the elderly. RSV vaccine development has been hampered by results of clinical trials in the 1960s, when formalin-inactivated whole-RSV preparations adjuvated with alum (FI-RSV) were found to predispose infants for enhanced disease following subsequent natural RSV infection."

In their study, the virologists "reproduced this apparently immunopathological phenomenon in infant cynomolgus macaques and identified immunological and pathological correlates."

"Vaccination with FI-RSV induced specific virus-neutralizing antibody responses accompanied by strong lymphoproliferative responses. The vaccine-induced RSV-specific T cells predominantly produced the Th2 cytokines interleukin-13 (IL-13) and IL-5," reported the researchers.

"Intratracheal challenge with a macaque-adapted wild-type RSV 3 months after the third vaccination elicited a hypersensitivity response associated with lung eosinophilia. The challenge resulted in a rapid boosting of IL-13-producing T cells in the FI-RSV-vaccinated animals but not in the FI-measles virus-vaccinated control animals," said Deswart and colleagues.

They also reported that "[t]wo out of seven FI-RSV-vaccinated animals died ...