Comparison of protective immunity elicited by recombinant vaccinia viruses that synthesize E or NS1 of Japanese encephalitis virus.

Immunization with recombinant vaccinia viruses that specified the synthesis of Japanese encephalitis virus (JEV) glycoproteins protected mice from a lethal intraperitoneal challenge with JEV. Recombinants which coexpressed the genes for the structural glycoproteins, prM and E, elicited high levels of neutralizing (NEUT) and hemagglutination inhibiting (HAI) antibodies in mice and protected mice from a lethal challenge by JEV. Recombinants expressing only the gene for the nonstructural glycoprotein, NS1, induced antibodies to NS1 but provided low levels of protection from a similar challenge dose of JEV.

Flavivirus type-specific antigens produced from fusions of a portion of the E protein gene with the Escherichia coli trpE gene.

Based on previous data showing that JEV and DEN-1 fusion proteins can be used as antigens, we engineered analogous fusion proteins for the same regions of the E proteins of DEN-2, DEN-3, and DEN-4, using the polymerase chain reaction. The resulting fusion proteins were tested in a modified ELISA for their reactivity with mouse immune ascitic fluids (MIAF) generated against 10 different flaviviruses. The results showed that these recombinant antigens could be used as type-specific immunological reagents, and suggest that these antigens could serve as the basis for rapid, safe, and inexpensive flavivirus serosurveys.

Purification and properties of an antivenom factor from the plasma of the South American rattlesnake (Crotalus durissus terrificus).

The lethal toxicity of Crotalus durissus terrificus (Crotalinae, Viperidae) can be attributed mainly to the presence of a neurotoxic protein, crotoxin, which also shows phospholipase A2 activity. It has been previously demonstrated that both lethal and phospholipase A2 activities of crotoxin can be neutralized by an alpha 1-globulin factor that is present in the homologous blood. Crotalus durissus terrificus plasma also renders some degree of protection to mice against the lethal toxicity of heterologous venoms from snakes of the genus Bothrops (Crotalinae, Viperidae), but not of the genus Micrurus (Elapinae, Elapidae).