Genetic variations of nucleoprotein gene of influenza A viruses isolated from swine in Thailand.
BACKGROUND
Influenza A virus causes severe disease in both humans and animals and thus, has a considerably impact on economy and public health. In this study, the genetic variations of the nucleoprotein (NP) gene of influenza viruses recovered from swine in Thailand were determined.


RESULTS
Twelve influenza A virus specimens were isolated from Thai swine. All samples were subjected to nucleotide sequencing of the complete NP gene. Phylogenetic analysis was conducted by comparing the NP gene of swine influenza viruses with that of seasonal and pandemic human viruses and highly pathogenic avian viruses from Thailand (n = 77). Phylogenetic analysis showed that the NP gene from different host species clustered in distinct host specific lineages. The NP gene of swine influenza viruses clustered in either Eurasian swine or Classical swine lineages. Genetic analysis of the NP gene suggested that swine influenza viruses circulating in Thailand display 4 amino acids unique to Eurasian and Classical swine lineages. In addition, the result showed 1 and 5 amino acids unique to avian and human lineages, respectively. Furthermore, nucleotide substitution rates showed that the NP gene is highly conserved especially in avian influenza viruses.


CONCLUSIONS
The NP gene sequence of influenza A in Thailand is highly conserved within host-specific lineages and shows amino acids potentially unique to distinct NP lineages. This information can be used to investigate potential interspecies transmission of influenza A viruses. In addition, the genetic variations of the NP gene will be useful for monitoring the viruses and preparing effective prevention and control strategies for potentially pandemic influenza outbreaks.
Thippamom
Nattakarn
N
Emerging and Re-emerging Infectious Diseases in Animals, Research Unit, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand.
Sreta
Donreuthai
D
Kitikoon
Pravina
P
Thanawongnuwech
Roongroje
R
Poovorawan
Yong
Y
Theamboonlers
Apiradee
A
Suwannakarn
Kamol
K
Parchariyanon
Sujira
S
Damrongwatanapokin
Sudarat
S
Amonsin
Alongkorn
A
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D016000:Cluster Analysis; D017124:Conserved Sequence; D014644:Genetic Variation; D009980:Influenza A virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D019590:Nucleocapsid Proteins; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D016601:RNA-Binding Proteins; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013552:Swine; D013553:Swine Diseases / Q000821:virology*; D013785:Thailand; D014758:Viral Core Proteins
C048842:NP protein, Influenza A virus; D019590:Nucleocapsid Proteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014758:Viral Core Proteins