TIPSHEET
Highlights from the Journals of the American Society for Microbiology
January 1998
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HEPATITIS G MAY BE SEXUALLY TRANSMITTED
A study of the prevalence of hepatitis G in Sweden and Honduras suggests that the traditionally accepted view of the disease as purely bloodborne may not be entirely correct. The results of the study by researchers at the Karolinska Institute and Huddinge University Hospital in Sweden and the Universidad Nacional Autonoma de Honduras, appears in the January 1998 issue of the Journal of Clinical Microbiology.
The researchers studied the prevalence of HGV and correlation with bloodborne disease risk factors, such as intravenous drug use, in 387 subjects from both Sweden and Honduras. HGV infection was found to be related to common risk factors for bloodborne infections in both countries, but the Swedish study identified a relatively high infection rate in subjects with no risk factors.
"The high prevalence of HGV RNA in the healthy population and homosexual men emphasizes the question of whether chronic HGV infection may be transmitted by sexual contacts," say the researchers. "Thus, chronic HGV infection might also be transmitted by social contacts or other routes yet to be defined."
HGV is a recently identified relative of the hepatitis C virus. It generally causes a chronic infection, the effects of which are currently unknown. The virus is only known to be transmitted through blood products, though other routes of transmission may be possible.
(C. Lara, R. Halasz, A. Sonnerborg, and M. Sallberg. 1998. Detection of hepatitis G virus RNA in persons with and without known risk factors for blood-borne viral infections in Sweden and Honduras. Journal of Clinical Microbiology. 36:255-257.)
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GENE GUN SHOOTS DNA VACCINE INTO REPRODUCTIVE TRACT
Researchers at Harvard Medical School and the University of Massachusetts Medical School have developed a successful strategy for vaccinating the female genital tract using a DNA vaccine administered through a gene gun. They report their findings in the January 1998 issue of the journal Infection and Immunity.
In the study, the researchers used a gene gun, a helium gas pressure-driven device, to deliver microscopic gold particles coated with DNA directly into the mucosal membranes of the lower genital tract of female rats. They compared the immune responses in these rats with rats given other immunization strategies. In the rats given the gene gun DNA vaccine immune responses were sustained for at least 14 weeks while those immunized using other protocols did not consistently sustain significant vaginal immune responses beyond week 6.
"Vaccines for the female reproductive tract have potentially widespread applications, from the prevention of sexually transmitted diseases to contraception. No such vaccines, however are currently available, largely because of lack of information about how best to stimulate a protective immune response in the genital tract mucosa," say the researchers. "We have demonstrated that mucosal tissues are capable of expressing DNA-based antigens and that the vaginal mucosal route of immunization is more effective than systemic (skin) immunization in inducing a local vaginal immune response."
(J.B. Livingston, S. Lu, H. Robinson, and D.J. Anderson. 1998. Immunization of the female genital tract with a DNA-based vaccine. Infection and Immunity. 66:322-329.)
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BORNA VIRUS NEEDS LOW pH TO INFECT CELLS
Researchers from the Scripps Research Institute in La Jolla, California have identified what they believe to be the mechanism by which the Borna disease virus (BDV), which causes neurological problems in many animals and may be implicated in some neuropsychiatric disorders in humans, gains entry into cells to cause infection. They report their results in the January 1998 issue of the Journal of Virology.
In the study, the researchers discovered that BDV requires a low (acidic) pH in order to infect cells, suggesting that the virus is carried into the cell by endocytosis, a process in which the cell's plasma membrane surrounds and encloses the virus, bringing it into the cell. Further experiments support this hypothesis. They have also identified two proteins in the virus, GP-84 and GP-43, which are necessary for entry into the cell.
Borna disease was first recognized in Germany in the early 1800s as a neurological syndrome in horses. It is sometimes called "sad horse disease." The virus that causes it has only recently been identified. Since then, BDV has been found in animals other than horses, including sheep, cattle and cats, and experiments suggest that it may be capable of infecting all warm-blooded animals. Recent studies suggest that chronic BDV infection in humans may play a role in a variety of psychiatric conditions including schizophrenia, paranoid psychosis and major depression.
(D. Gonzalez-Dunia, B. Cubitt and J.C. de la Torre. 1998. Mechanism of borna disease virus entry into cells. Journal of Virology. 72:783-787.) *********************************************************
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