Mohiuddin Mudassar, Deng Shengchao, Zhu Lisai, Wang Guiping, Jia Aiqing
Guangdong Haid Institute of Animal Husbandry and Veterinary, Guangzhou, Guangdong, People's Republic of China.
Guangdong Provincial Key Laboratory of Pig Raising and Disease Control, Guangzhou, People's Republic of China.
Gut Pathog. 2024 Apr 8;16(1):21. doi: 10.1186/s13099-024-00597-w.
During the last decade, porcine epidemic diarrhea virus has detrimental consequences on swine industry, due to severe outbreaks especially in the suckling piglets. In March 2013, an outbreak was reported on a commercial swine farm in Guangdong Province, Southern China. A wild-type PEDV strain named as CHYJ130330 was identified, complete genome was sequenced and deposited in GenBank (accession no. KJ020932). The molecular epidemiological including evolutionary characteristics and pathogenicity assessment were explored during this study with particular interest and focus to develop this candidate strain for new vaccine. The isolates from China pre- and post-2013 shared 96.5-97.2% and 97-99% nt identity respectively with wild-type CHYJ130330 strain which during experimental studies has demonstrated high virulence and 100% mortality in 10 TCID group piglets within 5 days. The 22 reference strains selected from other parts of the world shared 98-99% identity with our sequence except Chinese (CV777) and S. Korean (vir.DR13, SM98 and atten.DR13) strains sharing 96.8, 97.6, 96.6 and 97.1% identity respectively. The phylogenetic tree revealed most strains reported after 2013 in GII genogroup while the prototype (CV777), S.korean and earlier Chinese (JS2008, 85-7mutant, Atten.vaccine, SD-M, LZC and CH/S) were GI Group. The amino acid sequence of CHYJ130330 E and M protein is highly conserved while ORF3 and N protein having 9 and 17 amino acid substitutions respectively in comparison to CV777 strain. The comparison of full length genome and the structural proteins revealed variations signifying that PEDV variant strains are still the main source of outbreaks in spite of continuous vaccination and also explain the variable trend of large scale outbreaks during this decade as compared to sporadic tendency of disease found before 2010. It is evident from this study that Chinese strains display significant level of mixing with the strains reported from other countries. The strain CHYJ130330 was also adapted successfully to Vero cell line and has shown high virulence in piglets. The information/findings will be helpful to develop a strategy for control of PEDV and have also shown that CHYJ130330 strain has strong virulence and is a more popular clinical strain in recent years, which has the potential to be developed into PEDV vaccine.
在过去十年中，猪流行性腹泻病毒对养猪业造成了严重后果，尤其是在哺乳仔猪中引发了严重疫情。2013年3月，中国南方广东省的一个商业养猪场报告发生了疫情。鉴定出一株名为CHYJ130330的野生型猪流行性腹泻病毒毒株，对其全基因组进行了测序并提交至GenBank（登录号：KJ020932）。本研究探讨了该病毒的分子流行病学，包括进化特征和致病性评估，特别关注并致力于开发这种候选毒株用于新型疫苗。2013年前和后的中国分离株与野生型CHYJ130330毒株的核苷酸同一性分别为96.5 - 97.2%和97 - 99%，在实验研究中，该毒株在10个半数组织培养感染剂量（TCID）组的仔猪中5天内表现出高毒力和100%的死亡率。从世界其他地区选择的22个参考毒株与我们的序列同一性为98 - 99%，但中国的（CV777）和韩国的（vir.DR13、SM98和atten.DR13）毒株分别具有96.8%、97.6%、96.6%和97.1%的同一性。系统发育树显示，2013年后报告的大多数毒株属于GII基因群，而原型毒株（CV777）、韩国毒株以及早期的中国毒株（JS2008、85 - 7突变株、减毒疫苗株、SD - M、LZ C和CH/S）属于GI基因群。与CV777毒株相比，CHYJ130330毒株的E和M蛋白氨基酸序列高度保守，而ORF3和N蛋白分别有9个和17个氨基酸替换。全长基因组和结构蛋白的比较揭示了变异，这表明尽管持续进行疫苗接种，但猪流行性腹泻病毒变异毒株仍是疫情爆发的主要来源，也解释了这十年间大规模疫情爆发的变化趋势与2010年前疾病散发趋势的不同。从本研究可以明显看出，中国毒株与其他国家报告的毒株存在显著程度的混合。CHYJ130330毒株也成功适应了Vero细胞系，并在仔猪中表现出高毒力。这些信息/研究结果将有助于制定控制猪流行性腹泻病毒的策略，也表明CHYJ130330毒株具有很强毒力，是近年来更流行的临床毒株，有潜力被开发成猪流行性腹泻病毒疫苗。
