Vibrio parahaemolyticus-killing virus identifed

Vp58.5 phage induce Vibrio  lysis.

A virus known to attack and weaken marine-borne bacteria has been responsible for fewer cases of Vibrio parahaemolyticus-infected humans, a Chilean scientist discovered.The Vibrio parahaemolyticus bacterium lives in marine waters and ‘hides’ in shellfish and fish. When these products are consumed by people, the organism travels to the colon and produces such discomforts as diarrhoea. According to official statistics, some 8,000 people were intoxicated in the region of Los Lagos in 2005. This summer, however, the figure did not rise above 800 cases of infection.

Researcher Romilio Espejo, of the University of Chile's Nutrition and Food Technology Institute (INTA), discovered that the virus Vp58.5, when not immeditately fatal to the bacteria, mortally infects it.Vibrio parahaemolyticus was detected in Chile in 1998, in Antofagasta, and later in the Los Lagos region. Two years before, the same strain has appeared on the coasts of Vietnam, El Mercurio reports.

"This pandemic strain is the first such pathogen to have dispersed around the world,” Espejo explained. The Vp58.5 is a specific virus that does not attack any other bacterium. The scientist confirmed that the first attack wipes out 30 per cent of the bacteria and remains latent in those that survive. Only one in 10 million is immune, he uncovered.

But those bacteria carrying the latent virus are "cursed," as the virus multiplies and kills under sun exposure. This explains the fall in intoxication cases, Espejo explained. Even though Vietnam and Antofagasta are already free of the strain, to soon be joined by the Los Lagos region, the INTA expert stated his research will continue given that the virus and the bacteria mutate constantly and creating new defences.

Future versions of the virus may be used to eliminate the mutated bacteria, when the latter manifests, Espejo speculated.

Consumer measures preventing Vibrio parahaemolyticus intoxication include: consuming only cooked shellfish and fish; Keeping the cold chain uninterrupted before consumption, as bacteria proliferate at room temperature or under the heat of the sun.

Source: Applied and Environmental Microbiology magazine, March 2009