Research Progress in production and measurement of neuraminidase from Streptococci spp.

Abstract:

Neuraminidase hydrolyzes the terminal neuraminic acid residue of glycoconjugations. It is used in bacteria for adhesion to host cells, plasma proteins, hemocyte and important barriers and for further colonization, penetration and spread. Thus, the enzyme is an important virulence factor for various bacteria. Streptococci are widely spread pathogens for zoonoses. The activity of neuraminidase could be detected in many Streptococci spp. Streptococcus pneumonia produces 3 neuraminidases (NanA, NanB, NanC). NanA not only catalyzes the sialic residue covering the adhesion receptor, but also accelerates the bacterial infection on host cells. NanB provides carbon source for the bacteria. NanC helps S. pneumonia invading into the brain. As for group B streptococcus and S. suis, the activity of neuraminidase has not been certified yet. Researchers tend to hold the view that the neuraminidase activity has lost through evolution as both kinds of bacteria contain sialic acid in their capsules. The preference for neuraminidase of S. pyogenes and group C, G and L streptococcus is similar with strong catalytic activity for saliva mucin which avails the proliferation in organizations containing saliva mucin. The neuraminidase in S. oralis and S. sanguis destroys the sialic chain in component of blood. In all, the functions of neuraminidase are closely related to the location of bacterial colonization. In the test of enzyme activity, thiobarbital is used in the 1960s. Now the fluorogenic substrate and spectrophotometric method, the more convenient and sensitive methods, are the main ways measuring the neuraminidase activity. This paper summarizes the category, properties, mechanism of neuraminidase produced by Streptococci as well as the relationship between the enzyme and virulence. The assays for detection of neuraminidase activity are also reviewed.