Isolation and characterization of a Sagiyama virus from domestic pigs.
In 2002, a strain of Sagiyama virus (SAGV) designated ML/Taiwan/02 was isolated from farmed pigs in Taiwan. The nsP1 and E1 gene sequences of the ML/Taiwan/02 strain shared 98.6 and 96.7% homology, respectively, with corresponding genes of a Japanese strain of SAGV. Nucleotide and amino acid sequence comparison revealed this strain of SAGV to be most closely related to Getah virus, as opposed to its current classification as a subtype of Ross River virus. To investigate the seroprevalence of SAGV infection in Taiwan, a total of 586 pig sera collected from 11 of 17 Taiwanese districts were tested for serum neutralizing antibodies (SNA) against SAGV. Results indicated that 51% of the samples had SNA titer > or = 4, and 40% had SNA titer > or = 48, indicative of repeated exposure to SAGV in the field. To study the pathogenicity of the ML/Taiwan/02 strain, this strain was experimentally inoculated into 4-week-old specific-pathogen-free pigs that were seronegative for SAGV. Viremia was detected during postinoculation days (PID) 2-4, when the SNA titer was < or = 16. By PID 7, viremia was no longer detectable, coinciding with the increase of SNA titer to > or = 48. Clinical illnesses or remarkable lesions were not observed. To the authors' knowledge, this is the first reported isolation of a strain of SAGV from pigs in the field. The virus is experimentally nonpathogenic to pigs but is moderately widespread, most likely via repeated exposure to virus-carrying mosquitoes.
Chang
Chia-Yi
CY
Animal Health Research Institute, Council of Agriculture, Tansui, Taipei, Taiwan.
Huang
Chin-Cheng
CC
Huang
Tien-Shine
TS
Deng
Ming-Chung
MC
Jong
Ming-Hwa
MH
Wang
Fun-In
FI
D018354:Alphavirus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001483:Base Sequence; D009500:Neutralization Tests / Q000662:veterinary; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012398:Ross River virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid; D016036:Seroepidemiologic Studies; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000821:virology*; D013624:Taiwan / Q000453:epidemiology; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics
D000914:Antibodies, Viral; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins