introduction
HIV/AIDS continues to be a dreaded killer. According to data from the NIH National Institute for Allergy and Infectious Diseases (NIAID), there are over 1 million people living with the disease in the U.S., with over 53,000 new infections each year and overall mortality since the start of the pandemic in the 80's of over 565,000 in the U.S.
The condition is due to an infection by the HIV virus, which characteristically attacks specific cells of the immune system, leading to a secondary and chronic immune deficiency state. The individual is thus open to usually lethal opportunistic infections, apart from the crippling effects of the HIV virus.
Treatment continues to be a challenge since preventive vaccination has not been possible since the start of the epidemic.
HIV medications
HIV is in a class of viruses called retroviruses. These have a characteristic genetic material called RNA, covered by a viral coat. On entering the human cell, the virus removes this coat and hijacks the host cell apparatus to produce another type of genetic material called DNA which is the same type of genetic material found in the human cells. Viral DNA is then incorporated into human DNA and the hijacked cell apparatus churns out numerous viral proteins and RNA which are assembled into infective viral units. The new viruses are then released with the bursting of the cell.
The fact that the whole lifecycle of the virus is inside the cell makes it quite challenging for treatment. Its incorporation into host cell genetic material makes HIV practically impossible to eliminate totally from the body. Advances made in the treatment of HIV/AIDS have been in the control of the infection by targeting certain intracellular processes specific to the virus and its multiplication. Different drugs have been developed for different steps of the viral replication process. A group of drugs called reverse transcriptase inhibitors, like AZT, target the viral agent that converts viral RNA to DNA. Another group of drugs called protease inhibitors, like Crixivan, target the viral agent that aids the production of viral protein components. Others like Fuzeon, inhibit viral fusion with cells. One other group called integrase inhibitors block the integration of viral genetic material into host cell genes.
These drugs all showed promise at their introduction to HIV/AIDS therapy, but a disturbing trend was noted in HIV. Unlike other viruses, this virus is capable of changing its characteristics from cell to cell and indeed from person to person in a process called mutation. Thus, a different strain of virus is developed on a regular basis even in the same individual. This has been the problem with vaccine development in HIV/AIDS. Mutation is also a problem with drug therapy because the virus develops strains that are resistant to the drug being used, particularly since the drugs cannot eradicate the virus completely, only achieving suppression of viral reproduction. Thus combination therapy is usually used with combinations of different anti-retroviral agents.
How HAART Works
HAART stands for highly active anti-retroviral therapy. It was developed by NIAID-supported researchers in response to the challenge of development of drug resistance in HIV treatment. In HAART, a combination of three drugs is used in treatment at once. The combination is usually one protease inhibitor like Indinavir and two reverse transcriptase inhibitors like Zidovudine (AZT) and Lamivudine or three different reverse transcriptase inhibitors like tenovir, emtricitabine and Efavirenz.
A combination of these drugs, all effective antiviral agents in their individual rights, drastically reduces the viral reproduction in individuals, practically freezing the progression of the disease. The clinical state of the individual improves dramatically. Opportunistic infections are kept at bay by the continued state of health of the individual's immune system. The virus also finds it difficult to develop resistance when it finds itself fighting practically on three fronts for survival.
The only snag here is that the drugs are to be taken for life, since the incorporation of viral genetic material into human genes means that anytime the drugs are withdrawn, viral replication will resume.
