Vibrio cholerae M66-2

Vibrio species represent a significant portion of the culturable heterotrophic bacteria of oceans, coastal waters and estuaries. Various species of this genus are devastating pathogens for finfish, shellfish and mammals. A Gram-negative, rod-shaped bacterium, V.cholerae is the etiological agent of cholera, a severe diarrheal disease that occurs most frequently in epidemic form. Cholera has been epidemic in southern Asia for at least 1000 years; epidemics are usually associated with poor sanitary conditions. Vibrio cholerae as a species includes both pathogenic and non pathogenic strains that vary in their virulence and gene content. There are 2 major serogroups that cause epidemic cholera, O1 and O139. Serogroup O1 is further classified into two biotypes, classical and El Tor, and into two major serotypes, Inaba and Ogawa.Cholera outbreaks are unique in that the date and place of the occurrence, and in some cases the causative strain, are known. The first 6 pandemics (1817 to 1923) were caused by classical strains, however the 7th, which erupted in 1961, was caused by the hitherto mild El Tor strain. Strain M66-2 is a 1937 Makassar outbreak isolate, which appears to be on the direct line to the 7th pandemic. Comparison of the 6th pandemic O395 strain with M66-2 and the 7th pandemic strain (El Tor Inaba N16961) shows that the 2 pandemic clones gained pandemic potential independently, and overall there were 29 insertions or deletions of one or more genes. The divergence date of the 6th and 7th pandemic clones is estimated to be about 1880 (adapted from 19115014). (HAMAP: VIBCM)