A genetically engineered poliovirus vaccine appears to be an effective new strategy for an AIDS vaccine in women. Researchers from the University of California system and the National Cancer Institute report in the August 2001 issue of the Journal of Virology a poliovirus-based vaccine that protects monkeys from a highly virulent strain of simian immunodeficiency virus (SIV). The vaccine is based on Sabin 1 and 2 vaccine strains against polio that were genetically engineered to display a variety of SIV proteins. Female macaques were then innoculated with this new virus and vaginally challenged with highly virulent strain of SIV. More than half the vaccinated group were protected against infection while all control monkeys became SIV positive. In addition, those vaccinated monkeys who became infected remained healthy while many in the control group progressed rapidly to clinical AIDS. "Here we provide the first report of protection against a vaginal challenge with a highly virulent SIV by using a vaccine vector," say the researchers. "It is possible that a similar strategy using a cocktail of multiple HIV antigens can be used to protect against diverse HIV strains."
(S. Crotty, C.J. Miller, B.L. Lohman, M.R. Neagu, L.Compton, D. Lu, F. X.-S. Lu, L. Fritts, J.D. Lifson and R. Andino. 2001. Protection against simian immunodeficiency virus vaginal challenge by using Sabin poliovirus vectors. Journal of Virology, 75: 7435-7452.)
Bacterial 'insults' induce drug resistance
Some bacteria don't need to be exposed to antibiotics to develop resistance, just other bacteria. Researchers from the U.S. Department of Agriculture and Iowa State University report in the August 2001 issue of the journal Applied and Environmental Microbiology that Salmonella bacteria exposed to a compound secreted by a strain of E.coli can develop multidrug resistance. The compound, known as microcin 24, is an antimicrobial peptide secreted by a strain of E. coli that causes urinary tract infections. Many bacteria produce microcins as a means of disabling and competing with nearby bacteria. In this study, the researchers were testing Salmonella to see if they developed resistance to microcin 24. Not only did they develop resistance to the microcin but also to multiple antibiotics.
"I appears that multidrug-resistant Salmonella can arise as a result of an insult from other pathogenic bacteria," say the researchers. "Microcin production gives an advantage to pathogenic E. coli while also potentially selecting for multidrug-resistant Salmonella."
(S.A. Carlson, T.S. Frana, and R.W. Griffith. 2001. Antibiotic resistance in Salmonella enterica serovar typhimurium exposed to microcin-producing Escherichia coli. Applied and Environmental Microbiology, 67: 3763-3766.)
Hepatitis C outbreak traced to gynecological surgery
Four women in Italy appear to have contracted the hepatitis C virus (HCV) while undergoing gynecological surgical procedures in the same operating room on the same day in 1998. This report, which illustrates the potential risk of HCV transmission in a surgical setting, appears in the August 2001 issue of the Journal of Clinical Microbiology.
"In March 1998 two women with recent HCV infection who had both undergone gynecological surgery on January 9, 1998, in the same operatin room were admitted to [the hospital]. An investigation was conducted to identify further cases, the likely source of infection and the route of transmission," say the researchers.
Researchers identified two additional women with acute HCV who had had surgery that day. Molecular testing of the virus suggests that all the infections came from a common source, which was identified as a woman known to have chronic HCV who had undergone surgery first that day. The mode of transmission is not known, but one thing all women had in common was the administration of the anaesthetic propofol from multidose vials. One other woman who had also had surgery that morning but did not contract HCV did not receive propofol.
"Two factors seem to have been decisive in cause this cluster of HCV infection: the operating schedule and a common vehicle of infection. Had the source patient been the last to be operated on, HCV infection might never have occurred," say the researchers. "This case emphasizes the risk of nosocomial tranmission and the importance of universal infection control procedures in the operating room."
(M. Massari, N. Petrosillo, G. Ippolito, L. Solforosi, L. Bonazzi, M. Clementi and A. Manzin. 2001. Transmission of hepatitis C virus in a gynecological surgery setting. Journal of Clinical Microbiology, 39: 2860-2863.)
Full text of the above articles can be access through the ASM homepage at: http://www.asmusa.org/pcsrc/tip.htm.