A 45 yr old male presents to the clinic requesting a HIV test. He had unprotected sexual contact with another man 3 weeks ago. Antibodies against which of the following will be detected first by ELISA or Western blot?

Antibodies against gp41 will be detected first by ELISA or Western blot. Antibodies to HIV usually appear within 3-6 weeks of primary infection. The appearance of HIV-binding antibodies occurs prior to the appearance of neutralizing antibodies. The only viral proteins that elicit neutralizing antibodies are the envelope proteins gp120 and gp41. The order of appearance of antibodies is as follows: Antibody to envelope gp41 > Antibodies to gag protein (p24 and p55) > Antibodies to envelope gp120 > Antibodies to gag protein p17 > Antibodies to pol gene products (p31 and p66). The earliest antigen to appear in blood following HIV infection is p24. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition