Plant virus jumps to humans

Pepper Virus Infecting People

It has always been assumed that plant viruses cannot infect animals, and vice versa. But French scientists have now found what they claim is the first evidence of a plant virus infecting humans — they say pepper virus is making people sick.

A team at the University of the Mediterranean in Marseilles, France, led by Didier Raoult, have found RNA from the pepper mild mottle virus in the faeces of 7% of the 304 adults they tested; those with the virus were more likely to report fever, itching and abdominal pain, the ‘New Scientist’ reported on Wednesday.

Not everyone is convinced, however. Because Raoult looked at many possible symptoms, he would be expected to find a few that randomly appear more common in virus positive people, according to Robert Garry, a virologist at Tulane University in New Orleans, Louisiana. Moreover, in order to enter a cell and replicate, a virus must bind to a receptor on its surface, and a plant virus would be highly unlikely to recognize a receptor on a human cell, Garry said.

One possibility, Raoult said, is that the virus does not infect human cells directly. Instead, the naked viral RNA may alter the function of the cells via a mechanism similar to RNA interference, in which presence of certain RNA sequences can turn genes on and off.

The study identified a local source of Pepper mild mottle virus (PMMoV), a plant virus, and linked the presence of PMMoV RNA in stool with a specific immune response and clinical symptoms. Although clinical symptoms may be imputable to another cofactor, including spicy food, their data suggest the possibility of a direct or indirect pathogenic role of plant viruses in humans.  PMMoV RNA sequences were recovered from twelve (57%) of the twenty-one pepper or spice-containing food products picked for the research. Of all Tabasco sauce contained the highest viral load.

The virus does not infect human cells directly. Instead, the naked viral RNA may alter cell function via a mechanism similar to RNA interference, in which presence of certain RNA sequences can turn genes on and off. Pepper virus RNA sequences found from 12 (57%) of the 21 pepper or spice-containing food products picked for the study. Of all Tabasco sauce had the highest viral load.

Source:TOI