Least concentration of human immunodeficiency virus is seen in: (A) Saliva, (B) CSF, (C) Blood, (D) Semen
Answer is A. Viral load of HIV is maximum in blood, genital secretions like semen, and CSF

It also found in breast milk, saliva, lymphocytes, cell-free plasma, cervical secretions, saliva, tears, & minimal in urine

Saliva can contain fibronectin & glycoproteins, which prevent transmission of the virus.
A salivary protein called secretory leucocyte protease inhibitor also has anti-HIV activity