An HIV vaccine till date is considered as a hypothetical vaccine against the dreaded virus of all times which is the HIV(human immunodeficiency virus),which is responsible for causing AIDS(Acquired Immunodeficiency Syndrome).The invention of an HIV vaccine has become a part of struggle against the dreaded disease. Scientists the world over have been carrying out various experiments but all their efforts have been in vain till date. Although it has been believed that a vaccine can cure HIV infection but till date no advancements whatsoever are being made in this field. A preventive HIV vaccine is in the due course of its development and may be defined as any substance which is responsible for teaching the body’s immune system to recognize and protect it against the HIV infection. These HIV vaccines are believed to be made from man made materials and do not cause HIV infection inside the body.

It is believed that preventive HIV vaccines could have a number of outcomes like:

• To prevent infection in a number of people.
• Prepare one’s immune system to block any infection occurring and eliminating the virus completely.
• Delay or prevent the onset of AIDS.

The main and the basic aim of the HIV vaccine is protection from infection and also controlling of the HIV so spread. There is a vast difference between the preventive HIV vaccine and the therapeutic HIV vaccine. The preventive ones as specified earlier are used in case of is an HIV negative individual and the person concerned is to be protected from the virus whereas the therapeutic vaccine is used in case, the person is already infected with HIV and is to be treated against the infection ,i.e,one is to be cured.

Scientists to this day are making a lot of effort and progress in the field of vaccine against HIV but still no specific outcome has resulted and the dream of making an efficient vaccine has not yet come true. The effective antiviral vaccines (both preventive and as well as therapeutic) are based on two approaches:

• The "live attenuated" strategy which makes use of the entire virus in its weakened form. They can be generated by gene deletion. But in case of the HIV, this approach has been rejected because of its retroviral nature. It has also been observed that during the proviral stage, the gene deletion in the virus can lead to the inducing of the cancer in the body.
• According to the “whole killed" approach the killing of the virus takes place by engulfing it up by some forms of chemical treatments or with the help of the radiations. But, it has been observed that still the resulting virus from all these treatments has a glycoprotein layer at the surface and so the cells do not integrate. The major drawback faced by this strategy is that even if there is very less possibility that all viruses are not killed then they would give very dangerous results.

After the rejection of the above stated strategies the third approach which is to be taken into consideration is that the vaccine should be efficient as well as the one which doesn’t harm the immune system of our body. So, in order to fulfill the earlier specified type of vaccine scientists are carrying out alternative strategy in which they selectively choose peptides from the surface of the glycoproteins which are recognized as antigens by the immune system. But, the problem which arises in this case is the fact as to which region they should choose as the virus has the capability to mutate rapidly. For instance different strains of HIV may be present in the same individual so it becomes very difficult to comprehend about the nature of the virus.

Although each and every effort is being made but success has not been achieved yet.