Establishment of a multiplex PCR assay for detection of SS-2, APP and PM.

According to the gene sequences in GenBank of Streptococcus suis serotype 2(SS-2),Actinobacillus pleuropneumoniae (APP) and Pasteruella multocida (PM),three pairs of specific primers were designed to amplify the three fragments,respectively.A multiplex PCR assay was established to detect SS-2,APP and PM after optimizing the reaction condition.The results of sensitivity and specificity showed that the minimum DNA that multiplex PCR can detect were 48.3 pg (SS-2),581 pg (APP),5 pg (PM).All the predicted fragments were amplified but no band was observed from Escherichia coli,Salmonella choleraesuis,Eperythrozoon suis,Toxoplasma gondii.35 clinical samples were detected by the multiplex PCR.As the results,7 samples were positive for SS-2,5 positive samples for APP,and 7 positive samples for PM.The results showed that the multiplex PCR could be used to simultaneously detect the clinical samples infected with SS-2,APP,PM single-infection or co-infection.