Renson Patricia, Deblanc Céline, Bougon Juliette, Le Dimna Mireille, Gorin Stéphane, Mahé Sophie, Barbier Nicolas, Paboeuf Frédéric, Simon Gaëlle, Bourry Olivier
Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail (Anses), Unité Virologie Immunologie Porcines, BP 53, 22440 Ploufragan, France.
Université de Rennes (UNIR), Cité Internationale, 1 Place Paul Ricoeur, CS 54417, 35044 Rennes, France.
Vaccines (Basel). 2021 Apr 7;9(4):356. doi: 10.3390/vaccines9040356.
Modified-live vaccines (MLVs) against porcine reproductive and respiratory syndrome viruses (PRRSVs) are usually administrated to piglets at weaning when swine influenza A virus (swIAV) infections frequently occur. SwIAV infection induces a strong interferon alpha (IFNa) response and IFNa was shown to abrogate PRRSV2 MLV replication and an inherent immune response. In this study, we evaluated the impacts of swIAV infection on the replication of a PRRSV1 MLV (MLV1), post-vaccine immune responses and post-challenge vaccine efficacy at both the systemic and pulmonary levels. Piglets were either swIAV inoculated and MLV1 vaccinated 6 h apart or singly vaccinated or mock inoculated and mock vaccinated. Four weeks after vaccination, the piglets were challenged with a PRRSV1 field strain. The results showed that swIAV infection delayed MLV1 viremia by six days and post-vaccine seroconversion by four days. After the PRRSV1 challenge, the swIAV enhanced the PRRSV1-specific cell-mediated immunity (CMI) but the PRRSV1 field strain viremia was not better controlled. High IFNa levels that were detected early after swIAV infection could have been responsible for both the inhibition of MLV1 replication and CMI enhancement. Thus, whereas swIAV infection had a negative impact on humoral responses post-vaccination, it did not interfere with the protective effectiveness of the PRRSV MLV1 in our experimental conditions.
针对猪繁殖与呼吸综合征病毒（PRRSV）的改良活疫苗（MLV）通常在断奶时给仔猪接种，此时甲型猪流感病毒（swIAV）感染频繁发生。swIAV感染会诱导强烈的α干扰素（IFNa）反应，并且已表明IFNa可消除PRRSV2 MLV的复制以及固有免疫反应。在本研究中，我们在全身和肺部水平评估了swIAV感染对PRRSV1 MLV（MLV1）复制、疫苗接种后免疫反应以及攻毒后疫苗效力的影响。仔猪要么先接种swIAV，6小时后再接种MLV1，要么单独接种MLV1，要么进行 mock 接种和 mock 疫苗接种。疫苗接种四周后，用PRRSV1田间毒株对仔猪进行攻毒。结果表明，swIAV感染使MLV1病毒血症延迟了6天，疫苗接种后的血清转化延迟了4天。在PRRSV1攻毒后，swIAV增强了PRRSV1特异性细胞介导免疫（CMI），但PRRSV1田间毒株的病毒血症并未得到更好的控制。swIAV感染后早期检测到的高IFNa水平可能是抑制MLV1复制和增强CMI的原因。因此，尽管swIAV感染对疫苗接种后的体液反应有负面影响，但在我们的实验条件下，它并未干扰PRRSV MLV1的保护效力。
