Epidemiology and vaccine of porcine epidemic diarrhea virus in China: a mini-review

SUN, Dongbo; WANG, Xinyu; WEI, Shan; CHEN, Jianfei; FENG, Li

Recombination of the S gene of coronaviruses has been frequently reported [24, 31] . The PEDV S protein binds to a host cell receptor and triggers fusion of the viral and cellular membranes. It is likely that PEDV variants will continue to emerge, because of naturally occurring recombination events and mutations in the S gene. To identify possible recombination events within the S gene of PEDV, the S1 regions of 65 selected S genes from Chinese PEDV strains isolated from 2004 to 2015 (see Fig. 2 ) were screened using the Recombination Detection Program (RDP), GENECONV, Bootscan, MaxChi, Chimaera, 3Seq, PhylPro, LARD and SISscan methods embedded in RDP4. The recombination analysis revealed that four potential recombination events occurred between the 65 PEDV strains from China (Table 2) , and confirmation of the four potential recombination events was carried out by bootscan analysis and fast neighbor-joining trees, respectively (Fig. 3) . Of the four potential recombination events, one potential recombinant event occurred between a GI group strain and a GII group strain, and three potential recombinant events occurred within GI group strains. Most of the GI group Chinese strains consisted of PEDV strains that emerged from 2011 to 2015. The limited data demonstrated that recently emerging PEDV strains in China exhibited high variability and potential recombination of the S gene. In summary, although the evidence of naturally occurring recombination events is limited, possible recombination events between the S genes of Chinese PEDV strains should be monitored by extensive molecular epidemiology investigations in the future.