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Have you ever wondered what kinds of viruses can be found in human waste?

Mya Breitbart and team have been sequencing nucleic acids from fecal samples in order to find out. You might expect that we’d find viruses that infect humans or viruses that infect the bacteria in our gut.

I wouldn’t have expected to learn the result that they found.

A large number, 60% of the viral DNA sequences were from unknown viruses. That’s not a surprise. The surprise came when they looked at the RNA viruses.

Instead, the viral sequences most often came from a plant pathogen called the pepper mild mottle virus or PMMoV, which causes malformation and mottling in pepper plants.

They found PMMoV in three different libraries, all of which were sequenced with high-throughput pyrosequencing by collaborators at the Genome Institute of Singapore: two libraries of RNA viral genes from one individual’s feces at different times and a third library from another individual.

And the pepper virus wasn’t just detected in those two individuals. When the researchers expanded their search to include 18 people from San Diego or Singapore, they found PMMoV sequence in the feces of 78 percent of those living in San Diego and 67 percent of those living in Singapore. It was also detected in every raw sewage sample tested in 11 states.

Are people really eating that many peppers?

When Breitbart and her team tested a variety of foods for PMMoV, they didn’t find the virus in any of the fresh peppers tested. They did find it in several processed foods, though, including chili sauces, chili powder, and Indian curry.

Subsequent experiments indicated that the PMMoV that had passed through the human digestive system could successfully infect plants, suggesting humans unwittingly help the viruses get to their preferred hosts. “We are probably vectors of the virus,” Rosario said.

I guess the viruses like it hot, hot, hot.

Source: Andrea Anderson, “Viral Metagenomics Research Hints at Potential Ecological Influence of Treated Waste,” GenomeWeb News, June 4, 2008.

Comments

  1. #1 Hank Roberts
    June 4, 2008

    This explains why there’s such a huge push to declare sewage sludge a fertilizer instead of a toxic waste, eh? They need to get it on the law books as allowed, before it becomes obvious why it’s stupid.

  2. #2 Art
    June 4, 2008

    Rabies viruses proliferate in the salivary glands and infect the brain of animals to make them more likely to bite. The virus thus promotes its own spread.

    The PMMoV is ordering us to fertilize all the land with our wastes to advance its plan to take over the world. Our viral overlords have spoken. We are so ordered. So shall it be done.

  3. #3 ecoli
    June 5, 2008

    So, if they’re not in the fresh pepper plants, how did they get into the processed peppers? Perhaps a human virus that mutated?

    (an insidious PMMoV plot, to be sure)

  4. #4 Sandra Porter
    June 5, 2008

    I think the viruses are in fresh peppers, too.

    I don’t know the answer to the question, but I can think of a couple explanations. First, fresh peppers are mostly water and the material from dried peppers is more concentrated and that might explain the higher number. Second, the curry powders and chili powders might be imported or come from areas with higher concentrations of virus.

  5. #5 TomJoe
    June 6, 2008

    This explains why there’s such a huge push to declare sewage sludge a fertilizer instead of a toxic waste, eh?

    Farmers have been using animal manure, essentially the agricultural equivalent of “sewage sludge” for fertilizer for thousands of years. It’s high in nitrogen and phosphorus, two elements which are essential for healthy plant growth. That sludge also comes with another important chemical, water … which cuts down on irrigation costs.

    If the waste is properly treated (pathogen reduction, heavy metals removal), using sewage sludge should be a relatively efficient source of fertilizer and water for agricultural use. What else would you have done with it? You think it’s going to circulate in our sewers forever?

  6. #6 Vertebrat
    June 7, 2008

    PMMoV makes the peppers ugly, so infected ones are probably more likely to be processed rather than sold fresh.

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