广西猪流行性腹泻病毒感染病例的确诊与病毒S基因变异分析

Diagnosis of porcine epidemic diarrhea virus infection and analysis of its S gene variation in the Guangxi area

旨在对广西玉林市某规模化猪场免疫猪流行性腹泻病毒(porcine epidemic diarrhea virus, PEDV)AJ1102疫苗株和猪传染性胃肠炎病毒(TGEV)二联弱毒活疫苗后,猪群发生的腹泻进行确诊。通过对发病猪群临床观察、腹泻死亡仔猪病理解剖、实验室RT-PCR检测和基因测序,最终诊断为PEDV变异株感染。对PEDV变异毒株的S基因进行了扩增测序与分析发现,该毒株与国内外参考毒株S基因核苷酸同源性为92.8%~99.5%,氨基酸同源性为91.8%~99.2%;遗传进化分析表明,该PEDV毒株属于G2-a型变异毒株;氨基酸序列比较结果显示,该PEDV变异株氨基酸在多个位点发生了变异,S蛋白在第807位与第827位疏水性氨基酸处出现了较大的变化,在抗原位点第800~813位氨基酸处发生了较为明显的变化。本研究通过该例猪流行性腹泻病毒变异株感染的临床诊断和S基因变异分析,为PEDV病原学研究以及科学防控该病提供参考依据。

In order to confirm that the agents of diarrhea in pigs after immunization with bivalent live attenuated vaccine consisted of porcine epidemic diarrhea virus(the AJ1102 vaccine strain) and the transmissible gastroenteritis virus in a large-scale pig farm in Yulin City of Guangxi, porcine epidemic diarrhea virus(PEDV) variant strain infection was identified by clinical observation, pathological anatomy, RT-PCR and gene sequencing. The S gene of the PEDV in the samples was amplified, sequenced and analyzed. The nucleotide homology of the S gene with the reference strains at home and abroad was 92.8%-99.5%, and the amino acid homology was 91.8%-99.2%. Genetic evolution analysis showed that PEDV belonged to the G2-a variant strain;amino acid sequence comparison showed that the amino acid of the PEDV variant strain has been mutated at multiple sites. S protein analysis showed that the hydrophobicity of the S protein of this strain changed at amino acids 807 and 827;and at amino acids 800 to 813, the antigenicity of the S protein also changed. This study provided a basis for future research on PEDV etiology and for the scientific prevention and control of the disease, by clinical diagnosis and by S gene mutation analysis of a case of porcine epidemic diarrhea virus variant infection.