Geospatial and temporal associations of Getah virus circulation among pigs and horses around the perimeter of outbreaks in Japanese racehorses in 2014 and 2015

Abstract

BackgroundWe studied a recent epizootic of Getah virus infection among pigs in the southern part of Ibaraki Prefecture and the northern part of Chiba Prefecture, Japan, focusing on its possible association with outbreaks in racehorses in 2014 and 2015. The genomic sequence of a Getah virus strain from an infected pig was analyzed to evaluate the degree of identity with the strains from horses.ResultsSera were collected from pigs from September to December 2012 to 2015 in south Ibaraki (380 pigs in 29 batches), and from September to December 2010 to 2015 in north Chiba (538 pigs in 104 batches). They were examined by using a virus-neutralizing test for Getah virus. Seropositivity rates in 2012–2013 in south Ibaraki and 2010–2012 in north Chiba ranged from 0% to 1.6%. In south Ibaraki, seropositivity rates in 2014 (28.8%) and 2015 (65.0%) were significantly higher than those in the previous years (P < 0.01); 4/5 batches had positive sera in 2014 and 7/7 in 2015. In north Chiba, seropositivity rates in 2013 (14.1%), 2014 (17.8%), and 2015 (48.0%) were significantly higher than those in the previous years (P < 0.01); 6/27 batches had positive sera in 2013, 3/9 in 2014, and 5/5 in 2015. Complete genome analysis revealed that the virus isolated from an infected pig had 99.89% to 99.94% nucleotide identity to the strains isolated from horses during the outbreaks in 2014 and 2015.ConclusionsSerological surveillance of Getah virus in pigs revealed that the virus was circulating in south Ibaraki and north Chiba in 2014 and 2015; this was concomitant with the outbreaks in racehorses. The Getah virus strain isolated from a pig was closely related to the ones from horses during the 2014 and 2015 outbreaks. To our knowledge, this is the first convincing case of simultaneous circulation of Getah virus both among pigs and horses in specific areas.

Serological Survey of Getah Virus in Domestic Animals in Yunnan Province, China

“…Researchers had continuously detected the GETV neutralizing antibodies in pigs and horses in Ibaraki and Chiba of Japan (Bannai et al 2017). The results showed that in south Ibaraki, the seroprevalence of neutralizing antibody in pigs ranged from 0% to 1.6% in 2012-2013, but it was 28.8% and 65.0% in 2014 and 2015, respectively; In north Chiba, it ranged from 0% to 1.6% in 2010-2012, and was 14.1%, 17.8%, and 48.0% in 2013-2015, respectively.…”

An outbreak of Getah virus infection among pigs in China, 2017

“…Subsequently, outbreaks of GETV infection have occurred among horses in 1979, 1983, 2014 and 2015 in Japan (Bannai et al., ; Nemoto et al., ; Sentsui & Kono, ; Sugiura et al., ) and in 1990 in India (Brown & Timoney, ). In pigs, sporadic cases of GETV infection were reported in the 1980s in Japan (Shibata, Hatano, Nishimura, Suzuki, & Inaba, ; Yago, Hagiwara, Kawamura, & Narita, ); a recent seroepizootiologic investigation found GETV circulating in south Ibaraki and north Chiba in Japan, and this circulation was concomitant with the outbreaks in racehorses (Bannai et al., ).…”

Complete Genome Sequences of Getah Virus Strains Isolated from Horses in 2016 in Japan

“…An epidemic occurred at the same location in 2016. In addition, Getah viruses were isolated from mosquitoes in 2012 ( 7 ) and pigs in 2015 ( 8 ). Here, we read the complete genome sequences of the strains isolated from horses in 2016 and compared them with those of the strains recently isolated from horses, pigs, and mosquitoes.…”

“…Three strains (16-I-599, 16-I-674, and 16-I-676) from blood samples that were positive for Getah virus by reverse transcription-PCR ( 9 ) were successfully isolated in Vero cells ( 10 ). The genomes of the three strains were sequenced using the Ion Personal Genome Machine system (Thermo Fisher Scientific, Waltham, MA, USA), as described previously ( 8 ). The raw signal data were analyzed by using Torrent Suite version 5.0.5, and 14-I-605-C1 (GenBank accession no.…”

“…LC079088) was used as a reference sequence. The 5′- and 3′-end sequences were determined by rapid amplification of cDNA ends, as described previously ( 8 ).…”