COMPARISON OF AN IMPROVED POLYMERASE CHAIN-REACTION PROTOCOL AND THE INDIRECT HEMAGGLUTINATION ASSAY IN THE DETECTION OF EPERYTHROZOON-SUISINFECTION

The ability of an improved polymerase chain reaction (PCR) protocol to detect Eperythrozoon suis DNA in the blood of experimentally infected nonsplenectomized pigs was evaluated. The protocol utilizes previousl y described E. suis-specific primers and a properitary DNA-releasing r eagent in a 2-step amplification cycle followed by visualization of th e 492-bp amplification product on agarose gels. This PCR protocol succ essfully amplified E. suis DNA in blood from all postinfection samples and from the preinfection samples of 2 pigs, indicating preexisting n atural infections. Results of the indirect hemagglutination test on se rum samples from these pigs revealed that only 1 pig developed detecta ble antibody titers to E. suis infection during the 43-day study; that pig was determined by PCR to have been infected naturally with E. sui s prior to experimental inoculation. These results confirm previous re ports of poor antibody response of young pigs to E. suis infection and demonstrate the potential of PCR as a valuable tool for the diagnosis and study of E. suis infection in pigs.