RESUMO
The Heliothis armigera entomopoxvirus (HaEPV) genome encodes a predicted 68 kDa polypeptide related to the 'rifampicin resistance' protein of vaccinia virus (with 30 % identity), and an homologous swinepox virus protein (27% identity). We were unable to isolate an HaEPV genotypic variant encoding a predicted C-terminal truncated form of the protein, suggesting that the C terminus of the molecule may be essential to protein function, and, in turn, that this function may be essential to viral replication. HaEPV replication was substantially reduced in host cells exposed to rifampicin, but the observed cytotoxic properties of the drug made it impossible to determine the specific cause of that inhibition. We suggest that possession of a gene encoding a member of this polypeptide family might represent a defining molecular characteristic of the Poxviridae.
Assuntos
Antibióticos Antituberculose/farmacologia , Entomopoxvirinae/genética , Genes Virais , Rifampina/farmacologia , Vaccinia virus/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Resistência Microbiana a Medicamentos/genética , Dados de Sequência Molecular , Spodoptera , Replicação ViralRESUMO
Continuously replicating cell lines have been established from embryonic tissue and circulating hemolymph cells of the melolonthine Antitrogus parvulus Britton. Isozyme analyses demonstrated that cell lines from both tissue sources expressed essentially the same isoforms of enzymes as A. parvulus larvae and thus confirmed the species of their origin. Karyotype analyses showed that cells from both tissue sources had accumulated changes in chromosome number and morphology during culture. Availability of melolonthine-derived cells should assist in vitro studies of the pathogens of this important group of beetles.
Assuntos
Linhagem Celular , Besouros/citologia , Animais , Feminino , Hemolinfa , Mariposas/citologia , Spodoptera/citologiaRESUMO
We have determined the nucleotide sequence of the 3'-terminal half of the RNA genome of Murray Valley encephalitis virus (MVE) using seven overlapping cDNA clones; an estimated 80-90 nucleotides at the extreme 3'-end remain to be sequenced. In conjunction with previous sequence data for the 5' half (16), we can conclude that the MVE genome contains a long open reading frame of 10,302 nucleotides that encodes a polyprotein of 3434 residues. Comparison of the MVE deduced amino acid sequence with that of other flaviviruses shows that MVE is most closely related to Japanese encephalitis virus, consistent with serological studies. Using N-terminal amino acid sequence analysis, three nonstructural proteins (NS1, NS3, and NS5) have been identified and mapped on the MVE genome. MVE NS3 contains sequence motifs suggesting that its amino terminus may function as a serine protease. The central region of NS3 (in the linear amino acid sequence) has motifs that are found in NTP-binding proteins and helicases. MVE NS5 contains a conserved Gly-Asp-Asp sequence that is thought to be essential for RNA-dependent RNA polymerases.
Assuntos
Capsídeo/genética , Flavivirus/genética , Genes Virais , Proteínas do Core Viral/genética , Proteínas Virais/genética , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Códon , Dados de Sequência Molecular , RNA/química , RNA Helicases , Homologia de Sequência do Ácido Nucleico , Serina Endopeptidases , Proteínas não Estruturais ViraisRESUMO
The location of a major antigenic domain involved in the neutralization of an alphavirus, Ross River virus, has been defined in terms of its position in the amino acid sequence of the E2 glycoprotein. The domain encompasses three topographically close epitopes which were identified using three E2-specific neutralizing monoclonal antibodies in competitive binding assays. Nucleotide sequencing of the structural protein genes of monoclonal antibody-selected antigenic variants showed that for each variant there was a single nucleotide change in the E2 gene leading to a nonconservative amino acid substitution in E2. Changes were at positions 216, 234, and 246-251 in the amino acid sequence. The epitopes are in a region of E2 which, though not strongly conserved as to sequence among Ross River virus, Semliki Forest virus, and Sindbis virus, is conserved in its hydropathy profile among the three alphaviruses. The epitopes lie between two asparagine-linked glycosylation sites (residues 200 and 262) in E2. They are conserved as to position between the mouse virulent T48 strain and the mouse avirulent NB5092 strain.