HIV/AIDS still represents one of the most severe public health burdens in low and middle income countries. According to UNAIDS an estimate of 33.4 million people were living with HIV at the end of 2007 (http://www.who.int/hiv/data/2009_global_summary.gif) and the disease is considered pandemic by the WHO.
As there is still no cure for AIDS, research into an HIV vaccine is one of several approaches to reduce the global burden of AIDS, in addition to antiviral treatment and the promotion of safe sex.
The Human Immunodeficiency Virus (HIV) is a complex retrovirus that is transmitted mainly by unprotected sexual relations when infected sexual secretions of one partner enter in contact with mucous membranes of the other partner. The virus can also be transmitted when infected blood comes in contact with an open wound, which is, for example, the case for blood transfusions or the reuse of hypodermic needles. The virus may also be transmitted from mother to child during pregnancy, at childbirth or via breast feeding.
HIV infects key immune cells such as CD4 T Helper cells, macrophages and dendritic cells. After infection and a short acute phase, characterized by influenza-like symptoms, the disease enters a latent phase, on average 9 to 11 years, during which, without causing symptoms, the virus slowly replicates. The increasing virus load leads to a progressive destruction of the immune system, ultimately permitting the appearance of so-called opportunistic infections or HIV-related cancers, such as Kaposi’s sarcoma. The presence of any of more than 20 characteristic signs and or symptoms is the basis for the diagnosis of AIDS (acquired immunodeficiency syndrome).
Most patients die from opportunistic infections or malignancies associated with the progressive failure of the immune system, with the largest cause of AIDS morbidity today being tuberculosis co-infection.
About 33 million people worldwide live with HIV. Every year 2,7 million people are newly infected and every year 2 million people die from AIDS.
Two thirds of HIV infections are in sub-Saharan Africa.
A variety of vaccine strategies are currently in development and several are in clinical trials. There is no effective vaccine as to date.