Zhang Yuhan, Chen Yanjun, Yuan Weifeng, Peng Qi, Zhang Fanfan, Ye Yu, Huang Dongyan, Ding Zhen, Lin Longhua, He Houjun, Wu Qiong, Song Deping, Tang Yuxin
Department of Preventive Veterinary Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang 330045, China.
Key Laboratory for Animal Health of Jiangxi Province, Jiangxi Agricultural University, Nanchang 330045, China.
Animals (Basel). 2020 Sep 17;10(9):1674. doi: 10.3390/ani10091674.
To date, two genotypes, i.e., genotype 1 (G1) and genotype 2 (G2), of porcine epidemic diarrhea virus (PEDV) have been identified in swine, while the cross protection between the G2a and G1a subgenotypes is undetermined. Hence, in the present study, we attempted to observe a comparative pathogenicity and cross protection of G1a (CV777) and G2a (CH/JX/01) PEDVs. Initially pregnant sows were vaccinated twice with the two kinds of inactivated G1a- and G2a-based PEDV vaccines, respectively and the delivered neonatal piglets were challenged with prototype isolates of G1a and G2a PEDVs, and then the pathogenicity and cross-protection in neonatal piglets were observed. The results showed that CH/JX/01, a highly virulent and dominant G2a PEDV strain currently circulating in China had more severe pathogenicity in vitro and in vivo, and induced more strong immune responses, including higher titers of sIgA in maternal milk than that induced by CV777 PEDV, a prototype of G1a PEDV strain. All piglets from the sows immunized with CH/JX/01 could not only survive when challenged with the homologous PEDV, but also be fully protected when challenged with heterogenous G1a PEDV. In contrast, the piglets from the sows immunized with CV777 could be protected when challenged with homologous PEDV and only partially protected when challenged with heterologous G2a strain of PEDV (CH/JX/01). The findings of this study provide new insights into the pathogenicity, antigenicity, and immunogenicity of currently circulating wild type G2a PEDV, which might be valuable for the development of novel PEDV vaccine candidates with improved efficacy.
迄今为止，在猪群中已鉴定出猪流行性腹泻病毒（PEDV）的两种基因型，即基因型1（G1）和基因型2（G2），而G2a和G1a亚型之间的交叉保护作用尚未明确。因此，在本研究中，我们试图观察G1a（CV777）和G2a（CH/JX/01）两种PEDV的致病性比较及交叉保护作用。最初，分别用两种基于G1a和G2a的灭活PEDV疫苗对怀孕母猪进行两次免疫接种，然后对所产新生仔猪用G1a和G2a PEDV的原型毒株进行攻毒，进而观察新生仔猪的致病性和交叉保护作用。结果显示，CH/JX/01是目前在中国流行的一种高致病性且占主导地位的G2a PEDV毒株，其在体外和体内均具有更严重的致病性，并能诱导更强的免疫反应，包括母乳中sIgA的滴度高于G1a PEDV原型毒株CV777诱导产生的sIgA滴度。用CH/JX/01免疫的母猪所产的所有仔猪，在用同源PEDV攻毒时不仅能够存活，在用异源G1a PEDV攻毒时也能得到完全保护。相比之下，用CV777免疫的母猪所产仔猪在用同源PEDV攻毒时能够得到保护，而在用异源G2a毒株PEDV（CH/JX/01）攻毒时只能得到部分保护。本研究结果为目前流行的野生型G2a PEDV的致病性、抗原性和免疫原性提供了新的见解，这可能对开发具有更高效力的新型PEDV候选疫苗具有重要价值。
