The fourth-generation ELISA screen test is for the simultaneous qualitative detection of Human Immunodeficiency Virus Type 1 (HIV-1) p24 antigen and antibodies to HIV Type 1 (HIV-1 groups M and O) and HIV Type 2 (HIV-2). Results of the screen cannot be used to distinguish between the presence of HIV-1 p24 antigen, HIV-1 antibody, or HIV-2 antibody.
The reflexed HIV-1/ HIV-2 Antibody Differentiation test discriminates between HIV-1 and HIV-2 antibodies. Results for each type are reported.
If the HIV-1,2 Combo Antigen/Antibody screen is repeatedly reactive, then the HIV-1/ HIV-2 Antibody Differentiation test will be performed. Additional charges apply. A recommendation to order further testing on a separate specimen for HIV-1 Nucleic Acid will be made for certain results. This multi-test algorithm was proposed by the Centers for Disease Control and Prevention (CDC) and adopted by the Clinical Laboratory Standards Institute (CLSI) for the diagnosis of HIV.