Sattler Tatjana, Pikalo Jutta, Wodak Eveline, Revilla-Fernández Sandra, Steinrigl Adi, Bagó Zoltán, Entenfellner Ferdinand, Claude Jean-Baptiste, Pez Floriane, Francillette Maela, Schmoll Friedrich
Institute for Veterinary Disease Control, AGES, Robert-Koch-Gasse 17, 2340, Mödling, Austria.
Clinic for Ruminants and Swine, University of Leipzig, An den Tierkliniken 11, 04103, Leipzig, Germany.
BMC Vet Res. 2018 Apr 19;14(1):133. doi: 10.1186/s12917-018-1451-y.
Effective vaccines against porcine reproductive and respiratory syndrome virus (PRRSV), especially against highly pathogenic (HP) PRRSV are still missing. The objective of this study was to evaluate the protective efficacy of an experimental live attenuated PRRSV 2 vaccine, composed of two strains, against heterologous challenge with a Vietnamese HP PRRSV 2 field strain. For this reason, 20 PRRSV negative piglets were divided into two groups. The pigs of group 1 were vaccinated with the experimental vaccine, group 2 remained unvaccinated. All study piglets received an intranasal challenge of the HP PRRSV 2 on day 0 of the study (42 days after vaccination). Blood samples were taken on days 7 and 21 after vaccination and on several days after challenge. On day 28 after challenge, all piglets were euthanized and pathologically examined.
On days 7 and 21 after vaccination, a PRRSV 2 viraemia was seen in all piglets of group 1 which remained detectable in seven piglets up to 42 days after vaccination. On day 3 after challenge, all piglets from both groups were positive in PRRSV 2 RT-qPCR. From day 7 onwards, viral load and number of PRRSV 2 positive pigs were lower in group 1 than in group 2. All pigs of group 1 seroconverted after PRRSV 2 vaccination. PRRSV antibodies were detected in serum of all study pigs from both groups from day 14 after challenge onwards. In group 2, moderate respiratory symptoms with occasional coughing were seen following the challenge with HP PRRSV 2. Pigs of group 1 remained clinically unaffected. Interstitial pneumonia was found in four piglets of group 1 and in all ten piglets of group 2. Histopathological findings were more severe in group 2.
It was thus concluded that the used PRRSV 2 live experimental vaccine provided protection from clinical disease and marked reduction of histopathological findings and viral load in pigs challenged with a Vietnamese HP PRRSV 2 field strain.
针对猪繁殖与呼吸综合征病毒（PRRSV），尤其是针对高致病性（HP）PRRSV的有效疫苗仍然缺失。本研究的目的是评估一种由两种毒株组成的实验性减毒活PRRSV 2疫苗对越南HP PRRSV 2田间毒株异源攻击的保护效果。为此，将20头PRRSV阴性仔猪分为两组。第1组猪用实验疫苗进行免疫接种，第2组不接种。所有研究仔猪在研究第0天（接种疫苗42天后）接受HP PRRSV 2滴鼻攻击。在接种疫苗后的第7天和第21天以及攻击后的几天采集血样。在攻击后第28天，对所有仔猪实施安乐死并进行病理检查。
在接种疫苗后的第7天和第21天，第1组所有仔猪均出现PRRSV 2病毒血症，其中7头仔猪在接种疫苗后42天仍可检测到。在攻击后第3天，两组所有仔猪的PRRSV 2 RT-qPCR检测均呈阳性。从第7天起，第1组的病毒载量和PRRSV 2阳性猪数量均低于第2组。第1组所有猪在接种PRRSV 2疫苗后均发生血清转化。从攻击后第14天起，两组所有研究猪的血清中均检测到PRRSV抗体。在第2组中，用HP PRRSV 2攻击后出现中度呼吸道症状，偶尔咳嗽。第1组猪在临床上未受影响。在第1组的4头仔猪和第2组的所有10头仔猪中均发现间质性肺炎。第2组的组织病理学结果更严重。
因此得出结论，所使用的PRRSV 2实验性活疫苗可保护猪免受临床疾病的侵害，并显著减少用越南HP PRRSV 2田间毒株攻击的猪的组织病理学结果和病毒载量。
