Recombinant (r) preparations of interferons (IFN)-alpha, -beta, and -gamma were shown to protect mice against experimental virus infections with herpes simplex virus type 2 (HSV-2), and with three RNA-containing viruses from different families: Banzi, a flavivirus; Semliki Forest virus (SFV), an alphatogavirus; and Caraparu, a bunyavirus. The antiviral effects of the three different types of IFN were different with each virus. HSV-2 was the most sensitive virus, followed by SFV. Against Banzi virus, IFN-gamma was only effective when given both before and after infection. Against Caraparu virus, only IFN-gamma had a significant effect. These results suggest that IFN therapy might be valuable in human infections with these viruses, but that the correct choice of IFN and dose regimen is likely to be important.

2673 SUMMARYIn the present study, six lactate dehydrogenase-elevating virus (LDV) isolates obtained independently from inbred mice were compared by RNA oligonucleotide fingerprint analysis. The genome RNAs of four of the isolates gave unique fingerprint patterns. The patterns obtained for the other two isolates were similar, but not identical to one of the four unique patterns. These results indicate that more than one genotype of LDV exists and that virus isolates can be grouped by genotype. We have also demonstrated the presence of a Y-terminal poly(A) tract by direct sequencing of 3 '-3 2p_ labelled LDV genome RNA. The presence of a Y-terminal poly(A) tract distinguishes LDV from the members of the family Flaviviridae, which lack a 3'-poly(A), and justifies the current classification of LDV within the family Togaviridae.

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