Vaccine control and prevention of porcine reproductive and respiratory syndrome (PRRS), the most important disease of swine, is difficult to achieve. However, the discovery of broadly neutralizing antibody activity against porcine reproductive and respiratory syndrome virus (PRRSV) under typical field conditions opens the door to new immunologic approaches for robust protection. We show here that passive administration of purified immunoglobulins with neutralizing antibodies reduced PRRSV2 infection by up to 96%, and PRRSV1 infection by up to 87%, whereas immune immunoglobulins lacking neutralizing activity had no effect on viral infection. Hence, immune competence of passive immunoglobulin transfer was associated specifically with antibody neutralizing activity. Current models of PRRSV infection implicate a minor envelope glycoprotein (GP) complex including GP2, GP3, and GP4, as critical to permissive cell infection. However, conserved peptides comprising the putative cell attachment structure did not attenuate neutralization or viral infection. The results show that immunological approaches aimed at induction of broadly neutralizing antibodies may substantially enhance immune protection against PRRSV. The findings further show that naturally occurring viral isolates are able to induce protective humoral immunity against unrelated PRRSV challenge, thus removing a major conceptual barrier to vaccine development.
Bibliographical noteFunding Information:
Dr. Paul Yeske and Dr. Laura Bruner of Swine Vet Center, MN and Curt Froehle and Holden Farms provided access to sows, information on PRRSV outbreaks, disease and management, individual sow data and blood samples. Technical and bioinformatic assistance was provided by Kyra Martins, Cheryl Dvorak, Lucas dos Santos, Suzanne Stone, Xiong Wang, and Qinye Song. University of Minnesota Veterinary Diagnostic Laboratory staff assisted with animal procedures. Research was supported by National Pork Board Project #14-213, USDA National Needs Fellowship Grant #2008-38420-18726 for support of SRR, Agriculture and Food Research Initiative Competitive Grant no. 2016-67015-24928 from the USDA National Institute of Food and Agriculture, and NIH award T32 RR018719 for support of MCR. The authors declare no conflicts of interest. Appendix A
© 2018 Elsevier B.V.
- Neutralizing antibodies
- Neutralizing epitope
- Passive transfer