RESUMEN
L protein of hantaviruses is the RNA transcriptase and replicase that transcribes mRNAs and replicates the genomic RNA using antigenomic RNA as an intermediate. It also appears to have endonuclease activity. In this review, the current knowledge on the hantavirus L protein is presented including sequence motifs conserved in RNA polymerases, mechanisms of RNA synthesis and also the most recent findings on homologous RNA recombination and membrane association.
Asunto(s)
Orthohantavirus/fisiología , ARN Polimerasa Dependiente del ARN/fisiología , Proteínas Virales/fisiología , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Membrana Celular/virología , Núcleo Celular/virología , Chlorocebus aethiops , Variación Genética , Orthohantavirus/enzimología , Orthohantavirus/genética , Datos de Secuencia Molecular , ARN Viral/biosíntesis , ARN Polimerasa Dependiente del ARN/química , ARN Polimerasa Dependiente del ARN/genética , Alineación de Secuencia , Transcripción Genética , Células Vero , Proteínas Virales/química , Replicación ViralRESUMEN
In this study the L segment and the 5' and 3' termini of the S, M and L segments of the prototype Tula hantavirus (TUL) were sequenced, thus completing the first determination of the genome sequence of a hantavirus that has not been linked to any human disease. The TUL L segment comprises 6541 nt with one ORF of 6459 nt in the antigenome sense. This ORF potentially encodes a 2153 aa protein with a predicted molecular mass of 247 kDa. The amino acid sequence includes all the motifs conserved in RNA-dependent RNA polymerases. The 5' termini of all three genome RNAs (vRNAs) had the expected sequences conserved in hantaviruses. The 3' termini of M vRNAs were also conserved. However, the 3' termini of S and L vRNAs were heterogeneous as most of the sequenced 3' termini had either deletions of 1 to 22 nt or an extra 1 to 3 nt. No increase in the level of heterogeneity was seen in vRNAs of virions collected 3, 6, 9 and 12 days post-infection, suggesting that the heterogeneity already exists at the early stages of infection. The S and L vRNAs from infected cells had more truncated 3' termini than vRNAs from pelleted virus. Heterogeneity of the 3' termini of genome RNAs could decrease the efficiency of antigenome and mRNA syntheses and contribute to the slow growth observed for TUL and other hantaviruses in cell culture.
Asunto(s)
Genoma Viral , Orthohantavirus/genética , ARN Viral/genética , Humanos , Datos de Secuencia Molecular , Análisis de SecuenciaRESUMEN
Reverse transcription-PCR was used to analyze specimens from 20 Finnish nephropathia epidemica (NE) patients hospitalized during the period from October 1994 to January 1995. Blood and/or urine sediment specimens from seven patients were found to be positive for the genome sequences of Puumala hantavirus (PUU). PCR positivity of the specimens from the patients correlated well with the HLA-DRB1*0301 and HLA B8 alleles, which previously were shown to associate with severe courses of NE. Genetic analysis of the partial M-and/or S-segment sequences obtained from three severely ill NE patients revealed three PUU strains related to but distinct from previously reported strains from Finland. The M-segment sequence of PUU from bank voles trapped near the probable site of infection for one of the patients showed 98.2% identity to that of the PUU strain obtained from the patient, suggesting a link between wild-type PUU from the natural focus and the NE case. The S-segment sequences from the patient and the bank voles, however, showed substantially lower identity (95.8%). As this difference in diversity for M and S genes (1.8 and 4.2%) is atypical for PUU genetic drift, one possibility is that the strain acquired at the putative place of infection is a reassortant one.
Asunto(s)
Genoma Viral , Antígenos HLA/genética , Infecciones por Hantavirus/virología , Orthohantavirus/genética , Adulto , Anciano , Animales , Femenino , Infecciones por Hantavirus/inmunología , Infecciones por Hantavirus/transmisión , Haplotipos , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa , Roedores , Análisis de SecuenciaRESUMEN
A Vero E6 cell culture isolate of Tula virus (TUL), a hantavirus first detected in European common voles (Microtus arvalis and M. rossiaemeridionalis) by RT-PCR was obtained after initial passaging of TUL-infected vole lung samples in laboratory-colonized M. arvalis. TUL was defined as a classical serotype by a cross-focus-reduction neutralization test (FRNT) and was also shown to be distinct from other hantaviruses by haemagglutination inhibition assay. The sequences of S, M and partial L genome segments of the isolate were determined: the S segment was 99.9% identical to the original rodent-derived sequence. Serological evidence for a previous TUL infection was obtained from the serum of a blood donor living near a TUL focus in Moravia, Czech Republic, showing at least a 16-fold higher FRNT titre to TUL as compared to Puumala or other hantaviruses.