Tetravalent Vaccine Protects Monkeys.(from dengue virus/yellow fever)

2001 SEP 19 - (NewsRx.com & NewsRx.net) --

by N.R. Saltmarsh, staff medical writer - A newly constructed chimeric vaccine against dengue virus/yellow fever achieves antibody levels in rhesus monkeys

similar to those found in animals that are naturally immune.

F. Guirakhoo and colleagues in Cambridge, Massachusetts, expanded on previous work with a chimeric yellow fever-dengue type 2 virus (YF/DEN2) by creating three more chimeras.

"We describe construction of three additional YF/DEN chimeras using premembrane (prM) and envelope (E) genes of wild-type (WT) clinical isolates: DEN1 (strain PUO359, isolated in 1980 in Thailand), DEN3 (strain PaH881/88, isolated in 1988 in Thailand), and DEN4 (strain 1228, isolated in 1978 in Indonesia)," said Guirakhoo and coworkers.

These chimeras (YF/DEN1, YF/DEN3, and YF/DEN4) replicated to (approx)7.5 log[10] PFU/ml in Vero cells, were not neurovirulent in three- to four-week-old mice inoculated by the intracerebral route and were immunogenic in monkeys, the authors reported ("Construction, safety, and immunogenicity in nonhuman primates of a chimeric yellow fever-dengue virus tetravalent vaccine," Journal of Virology, August 2001;75(16):7290-7304).

All monkeys injected subcutaneously with one dose of these chimeric viruses (as monovalent or tetravalent formulation) developed viremia similar to that seen with the YF 17D vaccine (YF-VAX) but significantly less serious than that caused by the parent WT viruses, noted Guirakhoo and colleagues. Eight of nine monkeys inoculated with monovalent YF/DEN1 -3, or -4 vaccine and six of six monkeys inoculated with ...