Serological and molecular investigation of porcine sapovirus infection in piglets in Xinjiang, China.

Porcine sapovirus (PoSaV) is one of the important pathogens that cause acute gastroenteritis in piglets. A survey on the infection and epidemic status of PoSaV in Xinjiang Province, Northwest China, was conducted in this study. We applied indirect viral protein 1 (VP1)-ELISA method to detect specific antibodies in 1218 serum samples of 3-month-old piglets collected from eight regions in Xinjiang during 2013-2014 and also detected PoSaV in 146 diarrhea stools of piglets in these eight regions using RT-PCR technology. The results showed that the PoSaV-serological positive rates in piglets in eight different regions in Xinjiang were between 32.82 and 47.06% with a mean rate of 37.68%. The average positive rate of PCR in stools of piglets was 3.42%. Sequencing and comparative analysis of five PCR-amplified DNA fragments revealed that four epidemic strains of PoSaV (swine/XJ-KO1, swine/XJ-AK2, swine/XJ-KS1, and swine/XJ-SHZ1) shared high nucleotide and amino acid identities with Cowden strain, while strain swine/XJ-AK1 shared higher high identities with Po/OH-JJ681/2000/US isolate. Phylogenetic clustering further verified that the epidemic strains of PoSaVs, i.e., swine/XJ-KO1, swine/XJ-AK2, swine/XJ-KS1, and swine/XJ-SHZ1, belong to genogroup (GIII) while swine/XJ-AK1 belongs to GVI. This survey confirmed for the first time that PoSaV infection was common in piglets in Xinjiang, China, and that the epidemic strains exist at least in both GIII and GVI clusters. This study provided the useful epidemiological data for scientific control and prevention of this disease.