Tips from the Journals of the American Society for Microbiology: October 2001

October 11, 2001

Estrogen protects against toxic shock

Estrogen may play a role in protecting against endotoxic shock associated with Vibrio vulnificus infection, a finding that may help explain the vast difference between the infection in men and women. Researchers from the University of North Carolina report these findings in the October 2001 issue of the journal Infection and Immunity. Vibrio vulnificus is a bacterium that can cause endotoxic shock following the consumption of contaminated raw shellfish and is considered one of the most invasive and rapidly fatal human pathogens known, with fatality rates over 60%. Interestingly most of the cases occur in individuals over the age of 50 and, over the last 10 years, 85% of those who developed endotoxic shock were males. The researchers investigated whether hormone levels played a role in this gender-biased response to infection. Using rat models, they discovered that females who have had their ovaries removed were more likely to develop endotoxic shock. More importantly, estrogen replacement therapy significantly decreased mortality in male rats. "These results demonstrate that estrogen is providing protection against V. vulnificus lipopolysaccharide-induced endotoxic shock," say the researchers. (S.M. Merkel, S. Alexander, E. Zufall, J.D. Oliver, and Y.M. Huet-Hudson. 2001. Essential role for estrogen in protection against Vibrio vulnificus-induced endotoxic shock. Infection and Immunity, 69: 6119-6122.)

Vaccine may fight cervical cancer

A genetically engineered vaccine appears to direct the immune system to kill tumors caused by human papillomavirus 16 (HPV-16) report researchers from the University of Pennsylvania and Johns Hopkins University. Their research appears in the October 2001 issue of the Journal of Virology. HPV-16 is one of the most common sexually transmitted diseases and is associated with most cervical cancers. A protein known as E7 is believed to be required for tumor formation. The researchers developed a vaccinia virus genetically altered to express E7 as a potential treatment. Using the genetically altered virus as a vaccine, they believed they could stimulate the immune system to attack and kill tumor cells. In the study, half the mice treated with the vaccinia virus were tumor-free two months after innoculation. "The findings in this paper provide an additional option for the enhancement of immune responses to E7 and a possible immunotherapeutic agent for cervical cancers," say the researchers. (A. Lamikanra, Z.-K. Pan, S.N. Isaacs, T.-C. Wu, Y. Paterson. 2001. Regression of established human papillomavirus type 16 immortalized tumors in vivo by vaccinia viruses expressing different forms of HPV-16 E7 correlates with enhanced CD8+ t-cell responses that home to the tumor site. Journal of Virology, 75: 9654-9664.)

Contaminate the flower, contaminate the fruit

If tomato flowers are exposed to Salmonella, the bacteria may invade and grow inside the tomato itself, say researchers from the University of Georgia and the U.S. Food and Drug Administration. They report their findings in the October 2001 issue of the journal Applied and Environmental Microbiology. In the study researchers inoculated flowers of tomato plants with several species of Salmonella bacteria, and later tested the internal pulp of the resulting fruit. One fourth of the tomatoes tested contained Salmonella. "In the farm-to-table production, processing and distribution chain, there are various possible points of contamination of fruits and vegetables with disease-causing microorganisms," say the researchers. "Tomato stems and flowers are possible sites at which Salmonella may attach and remain viable during fruit development, thus serving as routes or reservoirs for contaminating ripened fruit. Interventions need to be applied to eliminate contamination of tomato fruits with Salmonella by preventing or minimizing its contact with tomato plants and fruits at all points from the farm to the consumer." (X. Guo, J. Chen, R.E. Brackett and L.R. Beuchat. 2001. Survival of salmonellae on and in tomato plants from the time of inoculation at flowering and early stages of fruit development through fruit ripening. Applied and Environmental Microbiology, 67:4760-4764.)
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Full copies of each article can be access through the ASM website at: http://www.asmusa.org/pcsrc/tip.htm

American Society for Microbiology

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