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Tips from the Journals of the American Society for Microbiology

American Society for Microbiology

Bovine-Like Coronavirus Found in Giraffe

For the first time researchers isolated a bovine-like coronavirus from a giraffe, confirming transmissibility from cattle to wild ruminants. They report their findings in the May 2007 issue of the Journal of Virology.

Coronaviruses (CoVs) belong to the Coronaviridae family and are responsible for a wide range of diseases in domestic and wild animals, as well as common colds in humans. Bovine CoV is a member of the same group as human CoVs therefore emphasizing the importance of research focusing on adaptive mutations and interspecies transmission.

In the study CoV particles were collected from fecal samples of three giraffes with mild-to-severe diarrhea. One of the giraffe samples was subjected to a series of tests and results revealed a close biological relationship between the giraffe CoV (GiCoV-OH3) and bovine CoV strains. Researchers then orally inoculated calves with the giraffe coronavirus and observed severe diarrhea and virus shedding within 2 to 3 days.

"In summary, we demonstrated that wild-ruminant CoVs are biologically, antigenically, and genetically similar to bovine CoVs from domestic cattle, suggesting the possibility of interspecies transmission and adaptation of CoVs to new hosts among the ruminant species," say the researchers.

(M. Hasoksuz, K. Alekseev, A. Vlasova, X. Zhang, D. Spiro, R. Halpin, S. Wang, E. Ghedin, L.J. Saif. 2007. Biologic, antigenic, and full-length genomic characterization of a bovine-like coronavirus isolated from a giraffe. Journal of Virology, 81. 10: 4981-4990).

Bites from Mosquitoes Not Infected with Malaria May Protect Against Future Infection

A new study suggests that bites from mosquitoes not infected with malaria may trigger an immune response limiting parasite development following bites from infected mosquitoes. The researchers from the Center for Global Health and Infectious Diseases, University of Notre Dame, Indiana and the National Institute of Allergy and Infectious Diseases, Bethesda, Maryland report their findings in the May 2007 issue of the journal Infection and Immunity.

Malaria, a major public health threat resulting in 3 million deaths annually, is transmitted to humans through mosquito bites. Emerging drug and insecticide resistance emphasize the urgent need for effective new vaccines.

In the study researchers compared immune responses of mice preexposed to uninfected mosquito bites followed by bites from mosquitoes infected with the malaria parasite, Plasmodium spp. and those of mice only exposed to infected mosquitoes. Results showed that in the early stages, mice preexposed to uninfected bites exhibited reduced parasite burdens in the liver and they remained lower during the blood-stage of the life cycle of infection.

"These data suggest that the addition of mosquito salivary components to antimalaria vaccines may be a viable strategy for creating a Th1-biased environment known to be effective against malaria infection," say the researchers. "Futhermore, this strategy may be important for the development of vaccines to combat other mosquito-transmitted pathogens."

(M.J. Donovan, A.S. Messmore, D.A. Scrafford, D.L. Sacks, S. Kamhawi, M.A. McDowell. 2007. Uninfected mosquito bites confer protection against infection with malaria parasites. Infection and Immunity, 75. 5: 2523-2530).

New Test May Allow for Rapid Detection of Salmonella in Meat

Researchers from Denmark have developed a 12-hour test for detecting Salmonella in meat. They report their findings in the May 2007 issue the journal Applied and Environmental Microbiology.

Salmonella is one of the main causes of food-borne illnesses worldwide. Detection methods have proved costly and laborious often requiring up to 5 days to get results. In recent studies real-time PCR technology has shown to offer several advantages in regard to speed, detection limit and cost.

In the study researchers developed a 12-hour DNA-based method for detecting Salmonella bacteria using polymerase chain reaction (PCR) and tested it in minced meat samples following 8 hours of preenrichment. Results were then compared to a reference culture method which previously tested 100 minced meat and poultry samples following 24 hours of preenrichment and showed relative accuracy and sensitivity of 99% and specificity of 100%.

"It was successfully demonstrated that the optimized 12-hour PCR method for Salmonella detection produced results comparable to those of the reference culture method with artificially inoculated pork meat and poultry samples," say the researchers. "The main advantage of the method developed is the reduced time of analysis, enabling faster release of Salmonella-free fresh meat."

(M.H. Josefsen, M. Krause, F. Hansen, J. Hoorfar. 2007. Optimization of a 12-hour TaqMan PCR-based method for detection of salmonella bacteria in meat. Applied and Environmental Microbiology, 73. 9: 3040-3048).


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