Many people live with the myth, that HIV and its harmful components are present in the saliva of a HIV positive person. Hence, kissing or sharing food with the patient can be contagious due to the presence of HIV in saliva. However, this is not true. Though the saliva might carry HIV viral RNA or proviral DNA, they are not harmful, when they reside in the human saliva.
The saliva does not carry HIV that could be infectious or contagious. This is because; the saliva does not offer a very favorable condition for the sustenance of HIV. In fact, saliva is a good agent of destroying this virus. It carries special antibodies that fight the HIV components. The antiseptic and "hypotonic" property of saliva is conditioned to destroy any foreign cell that is present in the mouth. It works as a natural defense mechanism in our body.
HIV requires a good quantity of salt for its survival. Therefore, blood gives HIV the most favorable environment for propagation. Saliva, on the contrary, deactivates 90% of the HIV- infected leukocytes, due to lack of salt. Leukocytes or the blood cells, which help in the transmission of HIV to the mucosal surface, fail to succeed in their purpose. The HIV in saliva expands and bursts, due to lack of salt.