RESUMO
Ebola virus (EBOV) was discovered in 1976 around Yambuku, Zaire. A lack of nomenclature standards resulted in a variety of designations for each isolate, leading to confusion in the literature and databases. We sequenced the genome of isolate E718/ME/Ecran and unified the various designations under Ebola virus/H.sapiens-tc/COD/1976/Yambuku-Ecran.
RESUMO
Marburgvirus (MARV) infections are generally lethal in humans and nonhuman primates but require in vivo lethal mouse variant selection by the serial transfer (passage) of the nonlethal virus into naïve mice to propagate a lethal infection. The passage of progenitor (wild-type) MARV or Ravn virus (RAVV) from infected scid BALB/c mouse liver homogenates into immunocompetent BALB/c mice results in the selection of lethal mouse viruses from within the quasispecies sufficient to establish lethality in immunocompetent mice. Genomic analysis in conjunction with the passage history of each mutation detailed the altered primary and secondary structures of the viral genomic RNA throughout the process. Key findings included the following: (i) a VP40:D184N mutation previously identified in the lethal guinea pig MARV genome was the first mutation to occur during the passage of both the MARV and RAVV variants; (ii) there was biased hypermutagenesis in the RAVV variant genome; (iii) there were two identical mutations in lethal mouse MARV and RAVV variants, VP40:Y19H in the PPPY motif and VP40:D184N in a loop structure between the two VP40 domains; (iv) the passage of wild-type MARV and RAVV in mice resulted in the selection of viral variants from among the quasispecies with different genotypes than those of the wild-type viruses; and (v) a lethal mouse RAVV variant had different tissue tropisms distinct from those of its wild-type virus. These studies provide insights into how marburgviruses manipulate the host for enzymes, metabolites, translation regulators, and effectors of the innate immune response to serve as potential viral countermeasures.
Assuntos
Evolução Molecular , Genoma Viral , Doença do Vírus de Marburg/virologia , Marburgvirus/genética , Marburgvirus/patogenicidade , Doenças dos Roedores/virologia , Seleção Genética , Substituição de Aminoácidos/genética , Animais , Análise Mutacional de DNA , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Mutação de Sentido Incorreto , RNA Viral/genética , Doenças dos Roedores/mortalidade , Inoculações Seriadas , Análise de Sobrevida , Tropismo ViralRESUMO
The complete genome sequences of 2 closely related plaque-derived variants of Marburg virus (MARV) species Lake Victoria marburgvirus, strain Musoke, indicate only a few regions of the RNA genome as underlying the differences between the 2 viruses. One variant is >90% lethal for guinea pigs and the other much less virulent, when guinea pigs are challenged with 1000 pfu of virus. Only 4 mutations that result in amino acid changes were identified, 1 in viral matrix protein VP40 and 3 in L, the RNA-dependent RNA polymerase. In addition, 6 differences were identified in noncoding regions of transcribed mRNA, and 1 silent codon change was identified in the L gene. Interestingly, the amino acid mutation identified in VP40 occurs in a nonconserved loop structure between 2 domains that are homologues only among MARV species. The L gene mutations were equally intriguing, clustering near a highly conserved motif in viral RNA-dependent RNA polymerases.
