Tips from the Journals of the American Society for Microbiology

12/21/04

New Herpes Vaccine May be Ready for Human Trials

New research suggests that a promising herpes vaccine may be ready for testing in humans say researchers from the National Institutes of Health and Harvard Medical School. Their findings appear in the January 2005 issue of the Journal of Virology.

Herpes simplex virus type 2 (HSV-2), or genital herpes, is a virus that infects approximately 22% of adult Americans. Bearing physical, psychological, and social effects on those who acquire it, it can pose an even more severe risk for immuno-compromised patients further emphasizing the need for an effective vaccine.

"In the aggregate, the burden of genital herpes has made development of more effective prevention strategies a health priority," say the researchers.

The study compared three different vaccines, a DNA vaccine, an antigenic vaccine and a live mutant strain of the type 2 virus, d15-29, in mice and guinea pigs. The live mutant strain, d15-29, showed minimal risk of causing disease as it is missing two of the genes necessary for replication and it stimulated a stronger immune response in both animals.

"Given its efficacy, its defectiveness for latency, and its ability to induce rapid, virus-specific CD8+-T-cell responses, the dl5-29 vaccine may be a good candidate for early-phase human trials," say the researchers.

(Y. Hoshino, S.K. Dalai, K. Wang, L. Pesnicak, T.Y. Lau, D.M. Knipe, J.I. Cohen, S.E. Straus. 2004. Comparative efficacy and immunogenicity of replication-defective, recombinant glycoprotein, and DNA vaccines for herpes simplex virus 2 infections in mice and guinea pigs. Journal of Virology, 79. 1: 410-418.)

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Houseflies May Contract E.coli from Cattle

Houseflies on cattle farms may contribute to the spread of Escherichia coli O157:H7 among animals, their food supply and potentially humans say researchers from Kansas. Their findings appear in the December 2004 issue of the journal Applied and Environmental Microbiology.

E. coli, one of the leading causes of food-borne diseases throughout the world, is responsible for more than 73,000 cases annually in the United States alone. E. coli O157:H7 can be life-threatening to children, the elderly and immuno-compromised patients. The intestinal tracts of cattle serve as the main reservoir for E. coli O157:H7 and the environment in which they are housed frequently attracts large populations of houseflies (HF).

"One of the potential modes of dissemination of this pathogen in the environment is by insects that are associated with animal feces and manure, primarily houseflies," say the researchers.

In the study houseflies were gathered from the feed bunks of a cattle farm in Kansas from June through October 2003. E.coli O157:H7 was found in every batch of houseflies collected, with 30% of the positive houseflies coming from a flaked corn shed. Ninety percent of the isolates contained genes indicating highly virulent strains.

"Our study demonstrated that houseflies carry virulent E. coli O157:H7 in the farm environment primarily during the summer and may play an important role in the ecology and transmission of this pathogen among individual cattle and potentially to the surrounding farm and urban environment," say the researchers. "Information on the association of E. coli O157:H7 with houseflies will assist in developing more comprehensive and quantitative risk assessments, as well as formulating E. coli O157:H7 intervention strategies that should include an effective HF management program."

(M.J. Alam, L. Zurek. 2004. Association of Escherichia coli O157:H7 with houseflies on a cattle farm. Applied and Environmental Microbiology, 70. 12: 7578-7580.)

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Harmful Bacterium Commonly Found in Poultry May Survive Refrigeration and Frozen Storage Combined

A common cause of foodborne disease from poultry products can survive refrigeration and freezing say researchers from Pennsylvania. Their findings appear in the December 2004 issue of the journal Applied and Environmental Microbiology.

Campylobacter bacteria are estimated to be responsible for 2.5 million cases of infection in the United States each year and 50% of those cases are attributed to contaminated poultry. Campylobacters are believed to achieve optimal growth in extremely warm temperatures while failing to thrive in temperatures below 86 degrees. Campylobacter jejuni appears to be the exception. Previous studies have shown a small portion able to withstand refrigeration and freezing independently, but the combined effect of both has yet to be tested.

In the study samples of ground chicken and chicken skin infected with C. jejuni were refrigerated, frozen or exposed to a combination of both. A significant portion of the bacteria were able to survive refrigerated and frozen temperatures in both ground chicken and chicken skin.

"A significant portion of C. jejuni on the poultry samples studied survived during refrigerated, frozen, and combined refrigerated and frozen storage," say the researchers. "The present study indicates that these treatments alone will not add a significant margin of safety with respect to this pathogen and cannot replace sanitary production and handling."

(S. Bhaduri, B. Cottrell. 2004. Survival of cold-stressed Campylobacter jejuni on ground chicken and chicken skin during frozen storage. Applied and Environmental Microbiology, 70. 12: 7103-7109.)

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