First Study of scpB Gene of Streptococcus agalactiae in Misiones, Argentina

Aims: Streptococcus agalactiae (GBS) is the leading cause of neonatal infections. GBS presents different surface proteins of antigenic characteristics. These proteins are encoded by several genes associated with virulence and host interaction acting on bacteria involved in invasiveness. The study of these surface protein antigens is important for the understanding of the pathogenesis and epidemiology of the infection. Several of these antigens have been proposed as components of multivalent conjugate vaccines. This study focuses on the presence of scpB gene encoding the C5a peptidase in GBS. Recent studies indicate that C5a peptidase vaccine formulations cause a long-term immune response and prevent GBS infection.
Methodology: A total of 200 Streptococcus agalactiae isolates were collected from vaginal or rectal swabs of pregnant women with 35 – 37 weeks gestational age. Conventional biochemical tests and commercial kits for latex particle agglutination (Phadebact Strep B Test-ETC-Bactus International AB Sweden) were used to identify those isolates. GBS strains were preserved in 20% skim milk at -80°C and were recovered to search the gene scpB. The scpB gene was investigated by conventional PCR. PCR products were visualized on 2% agarose gel gel stained with GelRed® (Biotium, Inc.; US) and visualized of bands in UV trans illuminator (MUV Model 21-312-220), using MP (D0017 marker DNA fragments made up of 10 double-stranded DNA molecular size of 100 to 1000 pb-INBIO, Argentina).
Results: The presence of the scpB gene was detected in 100% of Streptococcus agalactiae strains studied.
Conclusion: Our findings highlight the importance of including C5a peptidase in the design of a regional vaccine. The high specificity of the scpB gene in GBS, and the lack of homologous sequences in other bacterial genera and species, makes it a molecular marker that can be used in the diagnosis of colonization or infection by this microorganism.