News Release

Tips from the Journals of the American Society for Microbiology

Peer-Reviewed Publication

American Society for Microbiology

Free-Living Protozoa Found in Meat-Cutting Plants

A first time survey of free-living protozoa in meat-cutting plants showed high diversity rates of various species including those that could harbor food-borne pathogens say researchers from Ghent University, Belgium. They report their findings in the September 2008 issue of the journal Applied and Environmental Microbiology.

Protozoa are unicellular microorganisms that feed on bacteria. Sometimes the bacteria survive and replicate within the protozoa. Although bacterial presence in meat-processing environments has been previously examined, no studies of protozoan communities in these environments and their role in food contamination have been conducted.

In the study researchers used a series of methods to screen for protozoa in five meat-cutting plants and found communities of amoebae, ciliates, and flagellates to be present in all. Protozoa were detected in floor drains, standing water on the floor, soiled bars of cutting tables, plastic pallets and out-of-use hot water knife sanitizers. In addition, protozoa were identified on surfaces which come into direct contact with meat, such as conveyor belts, surfaces of cutting tables, and needles of meat tenderizers. Cultures were then refrigerated for seven days, after which protozoa were still detected in half of the samples. Through microscopic observations researchers identified up to 61 morphospecies.

"This survey showed that there is high protozoan species richness in meat-cutting plants and that the species included species related to known hosts of food-borne pathogens," say the researchers.

(M.J.M. Vaerewijck, K. Sabbe, J. Bare, K. Houf. 2008. Microscopic and molecular studies of the diversity of free-living protozoa in meat-cutting plants. Applied and Environmental Microbiology, 74. 18: 5741-5749.)


Naturally Occurring "Protective RNA" Used to Develop New Antiviral Against Influenza

Researchers from the University of Warwick, Coventry, United Kingdom have developed a new antiviral using naturally occurring influenza virus "protecting virus" that may defend against any influenza A virus in any animal host. They report their findings in the September 2008 issue of the Journal of Virology.

Human influenza virus A is not only responsible for seasonal disease in humans, it is also the cause of worldwide pandemics of which the last three resulted in millions of deaths all over the globe. Currently, live and killed vaccines countering specific strains of the flu are available, however a vaccine for a new pandemic strain would take months to develop. Also, increased resistance to antivirals currently on the market has emphasized the need for a new effective prophylactic and therapeutic treatment method.

The "protecting virus" contains an altered gene that makes it harmless and prevents it from reproducing in a cell. If another influenza virus invades the cell it still remains harmless, but rapidly reproduces and prevents infection by literally crowding out the new influenza strain.

In the study researchers used a "protecting virus" (known as 244) as an influenza A antiviral therapy and tested it in mice. A 120-ng intranasal dose completely protected mice simultaneously challenged with 10 50% lethal doses of influenza A/WSN (H1N1) virus. The 244 protecting virus also protected mice against strong doses of H2N2, H3N2, and H3N8. Prophylactic activity was maintained in mice at least 1 week prior to challenge and a clear therapeutic benefit was observed when administered 24 to 48 hours following a lethal challenge. Finally, the 244 protecting virus was noted to be 10- to 100-fold more active than previous defective influenza A viruses.

(N.J. Dimmock, E.W. Rainsford, P.D. Scott, A.C. Marriot. 2008. Influenza virus protecting RNA: an effective prophylactic and therapeutic antiviral. Journal of Virology, 82. 17: 8570-8578.)


New Astroviruses Identified in Bats

New research out of The University of Hong Kong, China and the HKU-Pasteur Research Centre, Hong Kong suggests that bats are reservoirs of a newly identified group of astroviruses, a significant agent of diarrhea in many species including humans. The findings are reported in the September 2008 issue of the Journal of Virology.

Bats are known to harbor many human zoonotic diseases such as Nipah, Ebola, and SARS and are increasingly recognized as hosts to a wide range of viruses, most of which establish long-term persistence in the animals. Astroviruses are associated with gastroenteritis in a variety of mammals including humans, but most commonly afflict children, the elderly and immunocompromised patients. Until now, most studies of astroviruses have focused on humans and domesticated animals, so little is known about potential carriers in wildlife.

In the study researchers collected fecal samples from a single habitat of apparently healthy insectivorous bats in Hong Kong over a one year period. Results showed high genetic diversity of viruses within a single habitat, with detection rates of 30% to 70% in Miniopterus magnater bats and 50% to 70% in Miniopterus pusillus bats. The researchers suggest that some of the bat astroviruses may be genetically linked to human astroviruses and believe that further studies are warranted.

"These findings are likely to provide new insights into the ecology and evolution of astroviruses and reinforce the role of bats as a reservoir of viruses with potential to pose a zoonotic threat to human health," say the researchers.

(D.K.W. Chu, L.L.M. Poon, Y. Guan, J.S.M. Peiris. 2008. Novel astroviruses in insectivorous bats. Journal of Virology, 82. 18: 9107-9114.)

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