RESUMEN
A novel orthobunyavirus, Bellavista virus, was isolated from Culex (Melanoconion) portesi mosquitoes in the Bellavista neighborhood of Iquitos, Peru, in 2009. The assembled segment L, M, and S sequences of strain PRD0552 are 6,950, 4,469, and 1,256 bases in length, respectively, comprising complete protein-coding sequences and partial terminal untranslated sequences.
RESUMEN
Group C orthobunyaviruses (family Bunyaviridae, genus Orthobunyavirus), discovered in the 1950s, are vector-borne human pathogens in the Americas. Currently there is a gap in genomic information for group C viruses. In this study, we obtained complete coding region sequences of reference strains of Caraparu (CARV), Oriboca (ORIV), Marituba (MTBV) and Madrid (MADV) viruses, and five clinical isolates from Peru and Bolivia, using an unbiased de novo approach consisting of random reverse transcription, random anchored PCR amplification, and high throughput pyrosequencing. The small, medium, and large segments encode for a 235 amino acid nucleocapsid protein, an approximately 1430 amino acid surface glycoprotein polyprotein precursor, and a 2248 amino acid RNA-dependent RNA polymerase, respectively. Additionally, the S segment encodes for an 83 amino acid non-structural protein, although this protein is truncated or silenced in some isolates. Phylogenetically, three clinical isolates clustered with CARV, one clustered with MTBV, and one isolate appeared to be a reassortant or a genetic drift resulted from the high variability of the medium segment which was also seen in a few other orthobunyaviruses. These data represent the first complete coding region sequences for this serocomplex of pathogenic orthobunyaviruses. The genome-wide phylogeny of reference strains is consistent with the antigenic properties of the viruses reported in the original serological studies conducted in the 1960s. Comparative analysis of conserved protein regions across group C virus strains and the other orthobunyavirus groups revealed that these group C viruses contain characteristic domains of potential structural and functional significance. Our results provide the basis for the developments of diagnostics, further genetic analyses, and future epidemiologic studies of group C viruses.
Asunto(s)
Genómica , Orthobunyavirus/genética , Orthobunyavirus/aislamiento & purificación , Bolivia , Genoma Viral/genética , Genómica/normas , Humanos , Orthobunyavirus/clasificación , Perú , Filogenia , Estándares de Referencia , Proteínas Virales/genéticaRESUMEN
BACKGROUND: During the 2010-2011 influenza season, a small sub-group of 2009 influenza A(H1N1) viruses (hereafter referred to as 2009 A(H1N1)) emerged that was associated with more severe clinical outcomes in Ecuador and North America. Genetically, the haemagglutinin (HA) of this sub-clade was distinct from HAs found in viruses associated with severe outbreaks in 2010 from the United Kingdom and from other global specimens isolated earlier in the season. OBJECTIVE: We report the emergence of a novel 2009 A(H1N1) variant possessing a re-emergent HA D222N mutation obtained from patients with severe respiratory illnesses and phylogenetically characterise these D222N mutants with other severe disease-causing variants clustering within a common emerging sub-clade. CASE REPORTS: In early 2011, three cases of 2009 A(H1N1) infection, two from Quito, Ecuador, and one from Washington, DC, USA, were complicated by severe pneumonia requiring mechanical ventilation, resulting in one fatality. These cases were selected due to the reported nature of the acute respiratory distress (ARD) that were captured in Department of Defence (DoD)-sponsored global influenza surveillance nets. RESULTS: Genetically, the 2009 A(H1N1) strains isolated from two of the three severe cases carried a prominent amino acid change at position 222 (D222N) within the primary HA receptor binding site. Furthermore, these cases represent an emerging sub-clade of viruses defined by amino acid changes within HA: N31D, S162N, A186T and V272I. Phylogenetically, these viruses share a high degree of homology with strains associated with recent fatal cases in Chihuahua, Mexico. DISCUSSION: Previously, enhanced virulence associated with the change, D222G, has been clinically linked to severe morbidity and mortality. Initial observations of the prevalence of a novel sub-clade of strains in the Americas suggest that viruses with a re-emergent D222N mutation may too correlate with severe clinical manifestations. These findings warrant heightened vigilance for emerging sub-clades of 2009 A(H1N1) and presumptive clinical implications.