Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is an enveloped, positive stranded RNA virus that infects pigs. Disease in a naive pig herd exposed to PRRSV can be devastating. Direct contact is the most prominent route of exposure. Clinical signs may include anorexia, fever, and lethargy. Reproductive failure is characterized by late-term abortions, increased numbers of stillborn fetuses, and/or premature, weak pigs. Infection during mid-gestation may be followed by abortions, mummified fetuses, early embryonic death, and infertility. Acute phases of disease typically last two to three months after which reproductive parameters often return to normal. However, a persistent reproductive form causes a decrease in the farrowing rate and irregular returns to estrus.
Piglets can be infected in utero, which is often associated with premature farrowing. Infected litters are weak, unthrifty, or splay-legged. Congenitally infected pigs can show signs of muscle tremors, eyelid edema, conjunctivitis and/or fever. Pigs may display respiratory dyspnea. PRRSV may persist in the respiratory tract and lymphoid tissues especially the tonsils for up to 157 days after an infection. Preweaning mortality has been reported to be as high as 80%. Prevalence of PRRSV in the United States swine herds is estimated to be 60-80%. Biological Mimetics, Inc. (BMI) is applying its Immune Dampening and Refocusing Technology to the PRRSV surface glycoproteins proteins.