Genetic characterization of nonstructural genes of H5N1 avian influenza viruses isolated in Thailand in 2004-2005.

The outbreak of highly pathogenic avian influenza (HPAI) viruses has severely disrupted poultry production and trade. Humans have been infected with HPAI H5N1 viruses and many have died. The nonstructural (NS) proteins of the virus are a factor that determines virulence. In this report, 80 NS genes of H5N1 HPAI viruses isolated from Thailand were completely sequenced and phylogenically analyzed. The percentages of identity and variable site NS1 genes were similar to NS2/nuclear export protein (NEP) genes. All NS1 genes from the samples were located in allelic group A. The NS1 and NS2/NEP proteins possess 225 and 121 amino acids, respectively. All NS1 protein samples had five amino acid deletions typical of avian influenza viruses isolated since 2002. An amino acid substitution at position 92 (G92E) of the NS1 protein, known to promote the inhibition of host immune responses, was also found in the samples.

Whole genome sequences of H5N1 influenza a virus isolated from a little grebe in Thailand.

This is the first report of the whole genome sequence of influenza A virus in an aquatic resident bird of Thailand. It was categorized into genotype Z according to its characteristics of a 20 amino acid deletion in neuraminidase and a five amino acid deletion in the nonstructural protein. The indicator for a highly pathogenic trait of the virus is the presence of a polybasic amino acid sequence at the cleavage site of HA0. The feature of resistance to the antiviral drug amantadine is found at the 31st amino acid position of M2 (serine to asparagine). Phylogenic analyses revealed that virus A/little grebe/Thailand/Phichit-01/2004 (H5N1) is closely related to the chicken and human isolates recovered from Thailand. The high degrees of similarity among the sequences and phylogenic trees indicate there was no difference between the viruses isolated from poultry and aquatic birds in Thailand at the time of study. The results also suggest the source of H5N1 avian influenza virus in the little grebe and others in Thailand may have the same origin.

Homogeneity of beta(0)-thalassemia codon 17 (A-->T) alleles in Northern Thailand using a direct DNA sequencing method.

The aim of this study was to characterize beta-globin gene micro-haplotype polymorphisms (frameworks) associated with a beta-thalassemia mutations common in Northern Thailand using a direct DNA sequencing method. A total of 11 beta-thalassemia major patients homozygous for the codon 17 (A-->T) mutation admitted to Chiang Mai University Hospital were examined. All 22 alleles were found to contain the Asian framework 3A. The homogeneity of the framework associated with the codon 17 (A-->T) mutation indicates a relatively recent origin of the codon 17 (A-->T) mutation. Similar studies in other East Asian populations may provide information concerning the origin and the migrational spread of this beta-thalassemia mutation.