An HIV-1 antibody Western Blot (WB) result is interpreted as positive when at least 2 of the 3 following bands are present: p24, gp41, and gp120/160. A positive HIV-1 antibody WB result following a reactive HIV-1/-2 antibody screening immunoassay (IA) or reactive rapid HIV-1/-2 antibody IA test supports HIV-1 infection at an undetermined stage of disease. Another specimen should be promptly submitted for HIV-1 Viral Load (HIVPCR), HIV-1 Proviral DNA by PCR, Qual (PHIV), or a repeat HIV-1 WB on first-time HIV-1 positive individuals to verify the diagnosis.
Indeterminate WB patterns can be found in up to 15% of persons without evidence of HIV infection. Repeatedly indeterminate results should be followed up with HIV-1 Viral Load (HIVPCR) or HIV-1 Proviral DNA by PCR, Qual (PHIV).
This test does not reliably detect anti-HIV-2 antibodies. HIV-2 is rare in most USA populations, but is linked with individuals from certain West African countries or their contacts. Should HIV-2 be suspected either clinically or due to a positive HIV-2 result from an HIV-1/-2 differentiation IA, please contact Marshfield Labs Customer Service for information on HIV-2 confirmatory testing. HIV infection is a nationally notifiable disease.