RNA extraction from swine samples and detection of influenza A virus in swine by real-time RT-PCR.

Real-time RT-PCR (rRT-PCR) assays are currently the method of choice in many laboratories for the detection and subtyping of influenza A virus (IAV) in swine. Traditionally, nasal swabs and lung tissues (sometimes broncho-alveolar lavage and tracheal tissues) are the primary specimens for IAV testing. However, oral fluids are becoming more common for IAV prognostic profiling. In this chapter, we describe (1) procedures of RNA extraction from the common clinical specimens, (2) two rRT-PCR assays for detection of IAV in swine, and (3) an rRT-PCR assay for subtyping swine IAV. RNA extraction procedures include a magnetic bead method optimized for extraction from nasal swabs and tissue homogenates and a magnetic bead method optimized for extraction from oral fluids. Two rRT-PCR assays for detection of swine IAV include a USDA-validated IAV rRT-PCR targeting the matrix gene and the USDA-licensed VetMAX™-Gold Swine Influenza Virus Detection rRT-PCR kit (Life Technologies) targeting the nucleoprotein and matrix genes. The swine IAV subtyping assays described here are multiplex SIV HA (H1 and H3) and NA (N1 and N2) subtyping rRT-PCR reagents from Life Technologies.