Encephalitis caused by Japanese encephalitis virus occurs in annual epidemics throughout Asia, making it the principal cause of epidemic viral encephalitis in the world. No currently available vaccine has demonstrated efficacy in preventing this disease in a controlled trial. We performed a placebo-controlled, blinded, randomized trial in a northern Thai province, with two doses of monovalent (Nakayama strain) or bivalent (Nakayama plus Beijing strains) inactivated, purified Japanese encephalitis vaccine made from whole virus derived from mouse brain. We examined the effect of these vaccines on the incidence and severity of Japanese encephalitis and dengue hemorrhagic fever, a disease caused by a closely related flavivirus. Between November 1984 and March 1985, 65,224 children received two doses of monovalent Japanese encephalitis vaccine (n = 21,628), bivalent Japanese encephalitis vaccine (n = 22,080), or tetanus toxoid placebo (n = 21,516), with only minor side effects. The cumulative attack rate for encephalitis due to Japanese encephalitis virus was 51 per 100,000 in the placebo group and 5 per 100,000 in each vaccine group. The efficacy in both vaccine groups combined was 91 percent (95 percent confidence interval, 70 to 97 percent). Attack rates for dengue hemorrhagic fever declined, but not significantly. The severity of cases of dengue was also reduced. We conclude that two doses of inactivated Japanese encephalitis vaccine, either monovalent or bivalent, protect against encephalitis due to Japanese encephalitis virus and may have a limited beneficial effect on the severity of dengue hemorrhagic fever.

SUMMARYA mouse monoclonal antibody (MAb) to dengue 4 (DEN-4) virus reacted with the antigen in the nucleus as well as in the cytoplasm of DEN-4-infected mammalian and mosquito cells, as demonstrated by the peroxidase-antiperoxidase staining method. The intranuclear antigen appeared to accumulate at the nucleoli, forming spots, whereas the cytoplasmic antigen appeared to be localized mainly in large perinuclear loci in the infected cells. The MAb-reactive antigen was produced in the presence of actinomycin D, which caused the accumulation in the nucleus to be altered to a dispersed pattern. Radioimmunoprecipitation analysis of [35S]methionine-labelled purified virions and Western blot analysis of the antigens prepared from the infected mammalian and mosquito cells showed that the MAb was directed against the DEN-4 virus core protein (M~ 15-5K). These results indicated that the DEN-4 virus core protein was partially transported, soon after its synthesis in the cytoplasm, into the nucleus and accumulated at the nucleoli.

SummaryIn dengue virus infected Aedes albopictus cells, electron-dense particles, larger than single ribosomes, were arranged on the cytoplasmic sides of rough endoplasmic reticulum (I~ER) membranes. Mature virions 40---45 nm in diameter as well as vesieulotubular structures 50--120 nm in diameter appeared in enlarged cisternae of I~EI~ filled with fine granular substance. Many of the mature virions and somewhat degenerated vesiculotubular structures remained to be enclosed in membranous structures presumably derived from I~.EI~, even after degeneration of infected cells. The findings suggest that development of dengue viruses in cultured A. albopictus cells takes place in close relationship with the activated membranes of RELY.Other morphological changes observed in dengue infected A. albopictus cells were 1. electron-dense "double-track structures" in areas of virion morphogenesis, 2. fine crystalline structures in type-2 dengue infected cells, and 3. aggregates of nucleoid structures, in cells persistently infected with type 2 dengue virus. The implication and nature of these structures in relation to virion morphogenesis remain to be investigated.

No abstract

No abstract

No abstract

No abstract

No abstract