Engineered E. Coli Secretes HIV Inhibitors

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Engineered

E. Coli Secretes HIV Inhibitors

Posted By Al Benson

NEW

YORK (Reuters Health) Jul 20 - Researchers at the National Institutes of

Health in Bethesda, land have genetically engineered a highly colonizing

probiotic strain of Escherichia coli to secrete potent HIV fusion inhibitor

peptides that block HIV fusion and entry into target cells.

According

to a report in the July 18th PNAS Early Edition, the bacteria are capable of

nonpathogenically colonizing the large intestine of mice for periods of weeks

to months and secreting inhibitory concentrations of HIV-gp41-hemolysin A

hybrid peptides on to mucosal surfaces on which HIV transmission occurs.

Dr.

Srinivas Rao and colleagues report that colonization occurs predominantly in

the colon and cecum, with lower concentrations of bacteria present in the

rectum, vagina and small intestine. " Histological and immunocytochemical

examination of the colon revealed bacterial growth and peptide secretion

throughout the luminal mucosa and in association with epithelial

surfaces, " they also note.

The

researchers believe this microbial microbicide should be safe in humans

because it is based on a commensal strain of bacteria (Nissle 1917) that has

already been used as an over-the-counter probiotic " with an excellent

biosafety record. " Administration of these bacteria to mice had no

inflammatory effects in the GI tract or vagina.

Dr.

Rao's group points out that " although the role of the natural microflora

in preventing infection by pathogenic microbes is well known, the concept of

using genetically engineered organisms for this purpose is a concept that has

not yet been tested in human beings. "

Nevertheless,

they conclude that the severity of the global HIV/AIDS epidemic coupled with

the lack of effective biomedical interventions " warrants such an

approach. "

PNAS

Early Edition 2005