Laboratoire de Ploufragan, ANSES, Agence Nationale de Sécurité Sanitaire, Ploufragan, France.
Université Bretagne Loire, Rennes, France.
Transbound Emerg Dis. 2018 Dec;65(6):1720-1732. doi: 10.1111/tbed.12945. Epub 2018 Jul 2.
From the severe porcine epidemic diarrhoea (PED) epidemics that struck in 2013 in the United States of America and other countries of North and South America, two types of porcine epidemic diarrhoea virus (PEDV) were isolated, namely the InDel and the non-InDel strains. They are differentiated by insertions/deletions in the S1 nucleotide sequence of the S gene, and differences in virulence were observed from the clinical cases. In 2014, a PED outbreak occurred in a pig farm in France, from which an InDel strain was isolated. This study aimed at comparing, under experimental conditions, the pathogenicity and the direct and indirect transmissions between a non-InDel strain isolated from a PED-affected piglet in 2014 in the USA and the French InDel strain. All infected pigs showed clinical signs with the non-InDel strain although only the inoculated and direct contact pigs showed clinical signs in the InDel strain group. Although viral RNA was detected in air samples with both strains, the indirect contact pigs remained free from infection with the InDel strain in contrast to the non-InDel group in which airborne transmission occurred in the indirect contact pigs. All infected pigs shed virus in faeces regardless of PEDV strain with 9 of 30 pigs showing intermittent faecal shedding. The transmission rate by direct contact was found to be 2.17-fold higher than the non-InDel strain compared with the InDel. In conclusion, the InDel strain was less pathogenic than the non-InDel strain in our experimental conditions. The transmission route differed between the two strains. Direct contact was the main transmission route for the InDel strain, although the non-InDel strain was transmitted through direct contact and indirectly through the air.
从 2013 年美国和南北美洲其他国家爆发的严重猪流行性腹泻（PED）疫情中，分离出了两种猪流行性腹泻病毒（PEDV），即插入缺失（InDel）和非插入缺失株。它们在 S 基因的 S1 核苷酸序列中存在插入/缺失，并且在临床病例中观察到了毒力的差异。2014 年，法国的一个猪场发生了 PED 疫情，从中分离出了插入缺失株。本研究旨在实验条件下比较 2014 年美国受感染仔猪分离的非插入缺失株和法国插入缺失株的致病性以及直接和间接传播。所有感染猪均表现出临床症状，而非插入缺失株组中仅接种猪和直接接触猪表现出临床症状。尽管两种毒株的空气样本中均检测到病毒 RNA，但间接接触猪未感染插入缺失株，而非插入缺失株组的间接接触猪则发生了空气传播感染。所有感染猪均从粪便中排出病毒，与 PEDV 株无关，其中 30 头猪中有 9 头出现间歇性粪便排出。直接接触传播率与非插入缺失株相比，插入缺失株高 2.17 倍。总之，在我们的实验条件下，插入缺失株的致病性低于非插入缺失株。两种毒株的传播途径不同。直接接触是插入缺失株的主要传播途径，而非插入缺失株则通过直接接触和空气间接传播。
