ABSTRACT
BACKGROUND: Annual seasonal influenza outbreaks are associated with high morbidity and mortality. OBJECTIVE: To index and document evolutionary changes among influenza A H1N1 and H3N2 viruses isolated from Thailand during 2006-2009, using complete genome sequences. METHODS: Nasopharyngeal aspirates were collected from patients diagnosed with respiratory illness in Thailand during 2006-2009. All samples were screened for Influenza A virus. A total of 13 H1N1 and 21 H3N2 were confirmed and whole genome sequenced for the evolutionary analysis using standard phylogenetic approaches. RESULTS: Phylogenetic analysis of HA revealed a clear diversification of seasonal from vaccine strain lineages. H3N2 seasonal clusters were closely related to the WHO recommended vaccine strains in each season. Most H1N1 isolates could be differentiated into 3 lineages. The A/Brisbane/59/2007 lineage, a vaccine strain for H1N1 since 2008, is closely related with the H1N1 subtypes circulating in 2009. HA sequences were conserved at the receptor-binding site. Amino acid variations in the antigenic site resulted in a possible N-linked glycosylation motif. Recent H3N2 isolates had higher genetic variations compared to H1N1 isolates. Most substitutions in the NP protein were clustered in the T-cell recognition domains. CONCLUSION: In this study we performed evolutionary genetic analysis of influenza A viruses in Thailand between 2006-2009. Although the current vaccine strain is efficient for controlling the circulating outbreak subtypes, surveillance is necessary to provide unambiguous information on emergent viruses. In summary, the findings of this study contribute the understanding of evolution in influenza A viruses in humans and is useful for routine surveillance and vaccine strain selection.
Subject(s)
Influenza A Virus, H1N1 Subtype/genetics , Influenza A Virus, H3N2 Subtype/genetics , Influenza, Human/virology , Amino Acid Sequence , Antigens, Viral/genetics , Antiviral Agents/pharmacology , Evolution, Molecular , Glycosylation , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Humans , Influenza Vaccines/genetics , Influenza, Human/epidemiology , Molecular Sequence Data , Phylogeny , Sequence Homology, Amino Acid , ThailandABSTRACT
Human bocavirus (HBoV) is a novel virus which can cause respiratory tract disease in infants and children. Recently, the prevalence of this virus was studied worldwide not only in the respiratory tract, but also in the gastrointestinal tract. The results of this study focusing on the HBoV detection in stool samples showed that HBoV could only be found in the stool of children with acute gastroenteritis (0.9%), not in the healthy control samples. Moreover, the complete coding sequences of these HBoV also showed very conserved sequences.
