Characterization of Streptococcus suis serotype 2 blood infections using RT-qPCR to quantify glutamate dehydrogenase copy numbers.

This study characterized the dynamic distribution of bacteria in the blood of pigs infected with Streptococcus suis serotype 2 using specific primers and a TaqMan probe designed to amplify the highly conserved S. suis serotype 2 glutamate dehydrogenase (GDH) gene sequences. Gene copy numbers were used to determine the concentration of bacteria in the blood of infected pigs over time using established TaqMan real-time quantitative PCR methodologies (RT-qPCR). The results showed that the detection limit of the RT-qPCR was 10 GDH gene copies. The advantages of utilizing this approach are the high levels of specificity, sensitivity and reproducibility. Bacteria were detected in the blood of infected pigs after 24 h post infection and S. suis GDH gene copies in the experimental group were highest (10(4.15)) on day 7 post infection. Data presented in this report demonstrate that the TaqMan RT-qPCR detection method can be used to characterize the dynamic changes occurring during S. suis serotype 2 blood infections in Bama minipigs thereby facilitating research associated with defining pathogenic mechanisms associated with this organism.