Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unsafe sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth (perinatal transmission). Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.
A strong immune defense reduces the number of viral particles in the blood stream, marking the start of secondary or chronic HIV infection. The secondary stage of HIV infection can vary between two weeks and 20 years. During this phase of infection, HIV is active within lymph nodes, which typically become persistently swollen, in response to large amounts of virus that become trapped in the follicular dendritic cells (FDC) network. The surrounding tissues that are rich in CD4+ T cells may also become infected, and viral particles accumulate both in infected cells and as free virus. Individuals who are in this phase are still infectious. During this time, CD4+ CD45RO+ T cells carry most of the proviral load.
During this stage of infection early initiation of antiretroviral therapy significantly improves survival, as compared with deferred therapy.
A recent study conducted by researchers in Japan found that an acid produced in the mouth because of gum disease might promote the progression of HIV, AFP/Yahoo! News reports. According to the researchers, the study, which will be published in the March issue of the Journal of Immunology, marks the first time a link has been discovered between gum disease and HIV, although previous research has linked gum disease with diabetes and heart disease. According to study author Kuniyasu Ochiai of Nihon University, butyric acid -- produced by a group of bacteria that causes periodontal disease --hinders an enzyme called HDAC, which blocks HIV from proliferating. Takashi Okamoto, molecular biology professor in central Japan's Nagoya City University, and Kenichi Imai, a research assistant at the university, also participated in the study.
Through in-vitro experiments, the researchers found that HIV quickly proliferated in two kinds of immune system-related cells after they were given culture fluid containing the gum disease-causing bacteria and butyric acid. Ochiai said, "Serious periodontal disease could lead to the development (of AIDS) among HIV-positive people ... although the probability largely depends on individual physical strength." He adds that there are "fears that even those [who] were unaware that they had contracted HIV could develop the epidemic once they have periodontal disease." The research team intends to confirm their finding in animal tests, Ochiai said.