Correlation among Various Putative Virulence Factors of Vibrio vulnificus

Lee, Shee Eun; Song, Jin Ahn

Abstract

The adhesion of Vibrio vulnificus to human host cells may play an important role in the infectious process of V. vulnificus septicemia. In this study, the relationship among the adhesibility of V. vulnificus to HeLa cell and other suggested virulence factors or parameters such as colony morphotype, surface hydrophobicity, and susceptibility to serum bactericidal activity was examined in eight different strains of opaque or translucent morphotypes. Mean bacterial count adhered to the HeLa cell was 16.6 and 34.8 in V. vulnificus C7184 and MO6-24/O strains, which have opaque morphotypes and showed HI of 0.426 and 0.495, respectively. In these two strains, viable bacterial count decreased only by one logarithmic scale after incubation with 75% NPS. Translucent strains A1402 and CVD752 (an acapsular transposon mutant of MO6-24/O) were equally very susceptible to NPS (decrease in viable count by 7 log scale), but they showed difference in adhesibility to HeLa cells. Bacterial count per HeLa was 3.7 and 48.2 respectively. HI of A1402 and CVD752 was 0.665 and 0.794. Translucent clinical isolates, WK16 and CN7, showed low adhesibility of 8.2 and 7.6 bacteria per HeLa cell and high hydrophobicity of HI 0.708 and 0.614, respectively. They were intermediately susceptible to the serum bactericidal activity. Environmental isolates, translucent MLT159 and opaque MLT166 showed adhesibility of 43.2 and 11.2 bacteria per HeLa cell and hydrophobicity of HI 0.588 and 0.697, respectively, but they were equally very susceptible to serum bactericidal activity. In conclusion, adhesibility of V. vulnificus strains to HeLa cell had nothing to do with the cell surface hydrophobicity and the susceptibility to serum bactericidal activity. The cell surface hydrophobicity of V. vulnificus was highly correlated with the susceptibility to serum bactericidal activity. Capsular polysaccharide seems to play an important role in the resistance to serum bactericidal activity. The hydrophobic interaction between bacteria and host cell appeared to have little effect in the adhesibility of V. vulnificus. Professional adhesion molecules of proteinceous pili or other afimbrial adhesins seems to play more important roles in the adhesion of V. vulnificus to host cells.