A sexually active patient presents with a pharyngitis , diarrhea and lymphadenopathy three weeks following exposure to an individual infected with HIV.
What is the test of choice for HIV in acutely infected individuals during the short period between infection and seroconversion?
a) viral lysate EIA
b) Fluoxetine
c) p24 antigen
d) Radioimmunoprecipitation assay
e) Polymerase chain reaction
Answer:
c) p24 antigen
Explanation
HIV infection should always be kept in mind when faced with a sexually active patient with lymphadenopathy, in particular the acute seroconverting illness as previously mentioned. This syndrome occurs on average 6 weeks after exposure in about half of all individuals infected with HIV. Symptoms often consist of pharyngitis, fever, diarrhea, maculopapular, truncal rash, and mucocutaneous ulcers in addition to lymphadenopathy. Of critical importance, these individuals will typically test negative for HIV at the time of illness, and so it is essential to send a p24 antigen if possible, and to retest for HIV 44 weeks later.
An alternative approach to diagnosing HIV-1 infection is to detect the presence of viral antigens in the blood. The best antigen for this purpose is the capsid antigen, p24, a viral structural protein that makes up most of the virus core particle. Because high titers of p24 antigen are present in the serum of acutely infected individuals during the short period between infection and seroconversion, p24 antigen assays are useful in the diagnosis of primary HIV-1 infection.