ASM journals tipsheet: May 2001

EXPERIMENTAL TREATMENT FOR EBOLA SHOWS PROMISE

An experimental treatment for Ebola virus infection using immune serum from survivors is effective in protecting mice from the disease, say researchers from the Centers for Disease Control and Prevention, Emory University and the U.S. Army Research Institute for Infectious Diseases. They report their results in the May 2001 issue of the Journal of Virology.

"Our data demonstrate that it is possible to confer protection against fatal infection with Ebola virus by transfer of polyclonal immune serum," say the researchers.

In the study, mice were injected with the deadly virus either just under the skin (subcutaneous) or in the abdomen (intraperitoneal). All the mice immunized subcutaneously showed now signs of illness and survived, while all those that received intraperitoneal injections died within 6 to 8 days. The researchers then collected immune serum from the surviving mice and tested its ability to both prevent and treat the disease in other mice. The serum successfully protected all mice exposed to the virus, regardless of whether it was administered before or after infection. It even worked on mice with impaired immune systems.

"Our data suggest that the use of convalescent-phase or immune serum as potential therapy for Ebola virus infection warrants further investigation," say the researchers.

(M. Gupta, S. Mahanty, M. Bray, R. Ahmed and P.E. Rollin. 2001. Passive transfer of antibodies protects immunocompetent and immunodeficient mice against lethal Ebola virus infection without complete inhibition of viral replication. Journal of Virology, 75: 4649-4654.)

BACTERIAL NASAL SPRAY COULD PREVENT FLU

A nasal spray containing bacteria from fermented milk may be a new preventive treatment for the flu. Researchers from Japan report promising results of this new therapy in mouse models in the May 2001 issue of the journal Clinical and Diagnostic Laboratory Immunology.

Probiotics are living bacteria that do no cause human disease but instead may help prevent the disease by altering human flora. In recent years, though, scientists have begun looking at the use of dead probiotic bacteria to stimulate immune responses to prevent disease.

In this study the researchers used killed Lactobacillus casei, bacteria originally isolated from the human intestine and commonly used to ferment milk, to stimulate an immune response in the upper respiratory tract of mice to protect them from influenza virus infection. The bacteria were administered to the mice in the form of an intranasal spray. Those that received the treatment had one tenth the level of influenza virus in their nasal cavities and a survival rate more than four times greater than those who did not receive the treatment before exposure to the influenza virus. "These findings suggest that intranasal administration of L. casei strain Shirota enhances cellular immunity in the respiratory tract and protects against influenza virus infection," say the researchers.

(T. Hori, J. Kyoshima, K. Shida and H. Yasui. 2001. Effect of intranasal administration of Lactobacillus casei Shirota on influenza virus infection of upper respiratory tract in mice. Clinical and Diagnostic Laboratory Immunology, 8: 593-597.)

BACTERIA INVOLVED IN MAKING VANILLA

An international group of researchers has isolated several species of bacteria that they believed may be instrumental in the curing of vanilla beans. These findings, which represent a first step towards simplifying the lengthy and expensive process of producing vanilla, are reported in the May 2001 issue of the journal Applied and Environmental Microbiology.

The curing process for vanilla beans is complex and slightly varied according the country where they are produced. Essentially it involves scalding the beans and then a 5 to 10 day process of "sunning and sweating" in which the beans are left in the sun all day and then put into boxes at night to retain the heat. The beans are then dried slowly for a month and finally put into plastic bags to condition for at least 2 months.

While much research has been done to identify the chemical compounds that make up the flavor of vanilla, little is known about how these chemicals are formed during the curing process. The possible role of bacteria in the formation of these chemicals has been suggested, but until now never investigated. In the study the researchers found several heat-loving bacterial communities developed on the beans during the "sunning and sweating" period, but little changes occurred in bacterial communities on the beans after this period.

"This study describes the microbial ecology of postharvesting processing of vanilla beans. It provides a base for further, more-detailed research on the contribution of microorganisms to vanilla flavor," say the researchers.

(W. F. M. Roling, J. Kerler, M. Braster, A. Apriyantono, H. Stam and H. W. van Verseveld. 2001. Applied and Environmental Microbiology, 67: 1995-2003.)

Copies of the full articles referenced above can be accessed through the ASM Website at: http://www.asmusa.org/pcsrc/tip.htm.