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Journal Highlights

Sin Nombre Virus Uses Variability as an Evasion Tactic

Sin Nombre virus (SNV), the agent behind hantavirus pulmonary syndrome, is believed to establish a chronic infection in deer mice, its natural reservoir. Now Ralph Feuer and his colleagues at the University of Nevada, Reno, suggest that the virus achieves this persistence through genetic variability.

SNV cloned from mice marked and recaptured in the field over a period of time enabled the researchers to detect even minor alterations. The researchers found a 0.15% variability in viruses from the blood and a 0.5% variation in the viruses from the spleen.

``These viruses are able to establish a persistent infection despite a strong host immune response,'' says coauthor Stephen St. Jeor. ``We think this diversity helps explain the evasion of the immune response.''

(R. Feuer, J. D. Boone, D. Netski, S. P. Morzunov, and S. C. St. Jeor. 1999. Temporal and spatial analysis of Sin Nombre virus quasispecies in naturally infected rodents. J. Virol. 73:9544-9554.) Abstract | Full Text

Inaccurate Measurements of Gene Transfer Events

Netherwood

Genetically modified organisms (GMOs) being developed for agriculture and food production have come under fire by critics concerned about their safety, particularly the potential for gene transfers to pathogens.

Using both in vitro and in vivo methods, Tracy Netherwood and colleagues at the University of Newcastle-upon-Tyne in Great Britain traced the presence of plasmids encoded into a probiotic strain of Enterococcus faecium fed to broiler chicks. Their results pointed out inadequacies in current measurement techniques.

``What we have shown is that the in vitro methodology does not accurately predict the rate of gene transfer in the avian gastrointestinal tract,'' Netherwood says. ``We require more accurate in vivo methodology to detect rare gene transfer events in the environment.''

(T. Netherwood, R. Bowden, P. Harrison, A. G. O'Donnell, D. S. Parker, and H. J. Gilbert. 1999. Gene transfer in the gastrointestinal tract. Appl. Environ. Microbiol. 65:5139-5141.) Abstract | Full Text

Gene Fusions Harnessed to Find Antibiotics

Baneyx

Despite advances such as high-throughput screening, the process of drug discovery is still an arduous task. Allison Bianchi and Francois Baneyx of the University of Washington, Seattle, propose a more efficient, ``smart'' assay system using gene fusions between stress promoters and reporter genes that are induced by antibacterial agents.

``The advantage with this system is that cells don't have to undergo growth inhibition to detect the activity of an antibiotic,'' Baneyx says. Moreover, ``traditional assays may overlook some compounds that have antibiotic activity'' because they are available only in low concentrations. This system also gives lead seekers some clues as to a potential antibiotic's cellular target. Eventually this system may be useful for tackling the problem of multidrug resistance, Baneyx adds.

(A. A. Bianchi and F. Baneyx. 1999. Stress reponses as a tool to detect and characterize the mode of action of antibacterial agents. Appl. Environ. Microbiol. 65:5023-5027.) Abstract | Full Text

Oral Bacteria May Contribute to Atherosclerosis

Experts continue to debate whether microbes are the culprits behind some cases of heart disease. Now Brian Dorn and his colleagues at the University of Florida, Gainesville, provide the first evidence that common oral pathogens can invade human coronary artery cells.

In vitro assays and electron microscopy showed that certain strains of P. gingivalis and P. intermedia were able to infect and remain metabolically active within coronary artery cells. The researchers suggest that this invasion may contribute to the injury that provokes atherosclerosis.

``It's been known for many years that periodontal bacteria can get into the bloodstream through chewing, brushing, and flossing, and it was thought that that was a pretty mild situation,'' says coauthor Ann Progulske-Fox. ``The data in this paper may indicate that it's not as innocuous as previously thought.''

(B. R. Dorn, W. A. Dunn Jr., and A. Progulske-Fox. 1999. Invasion of human coronary artery cells by periodontal pathogens. Infect. Immun. 67:5792-5798.) Abstract | Full Text

High Levels of Quinolone-Resistant Escherichia coli Found in Healthy Individuals

Through a 1992-1997 survey of quinolone-resistant Escherichia coli (QREC) in Barcelona, Spain, Javier Garau of the Universidad Autonoma de Barcelona and his colleagues found a significant jump in resistance in both a hospital setting and the community from 8.3% of isolates in 1992 to 22%.

``The high incidence of QREC in the feces of healthy people from the area was a surprise,'' the researchers say. Medical quinolone use alone would not explain this phenomenon, they add. They postulate resistance transmission from poultry, which in Spain are dosed with large amounts of enrofloxacin. ``These findings should reinforce the message that control of the spread of antibiotic resistance requires the prudent use of antibiotics not only in humans, but also in veterinary medicine,'' they conclude.

(J. Garau, M. Xercavins, M. Rodríguez-Carballeira, J. R. Gómez-Vera, I. Coll, D. Vidal, T. Llovet, and A. Ruíz-Bremón. 1999. Emergence and dissemination of quinolone-resistant Escherichia coli in the community. Antimicrob. Agents Chemother. 43:2736-2741.) Abstract | Full Text

DNA Replication Mechanism Conserved Across All Three Domains

Ishino

DNA replication and repair are such fundamental activities of life that the mechanisms of these functions are conserved across the domains Eukarya and Bacteria. Isaac Cann and his colleagues at the Biomolecular Engineering Research Institute in Osaka, Japan, now extend this conservation to include the Archaea as well.

The researchers cloned from the euryarchaeote Pyrococcus furiosus a gene for a homolog of proliferating cell nuclear antigen (PCNA), an essential factor in eukaryotic replication. Like PCNA, this archaeal homolog stimulates DNA synthesis by interacting with DNA polymerases. ``This finding is very important as the first stage for elucidating the archaeal DNA replication mechanism,'' says coauthor Yoshizumi Ishino. However, a counterpart of a molecule required to load PCNA onto the DNA helix in eukaryotes has yet to be found in archaea.

(I. K. O. Cann, S. Ishino, I. Hayashi, K. Komori, H. Toh, K. Morikawa and Y. Ishino. 1999. Functional interactions of a homolog of proliferating cell nuclear antigen with DNA polymerases in Archaea. J. Bacteriol. 181:6591-6599.) Abstract | Full Text