HIV - 1 Drug Resistance Assay ( RT)

HIV-1 reverse transcriptase (RT) is the viral enzyme that converts HIV-1’s single-stranded RNA into double-stranded DNA for integration into the host genome. It is a heterodimer (p66/p51) with RNA-dependent DNA polymerase and RNase H activities. RT’s essential role in replication makes it a primary antiretroviral drug target, inhibited by nucleoside/nucleotide and non-nucleoside RT inhibitors.

An HIV drug resistance test detects whether a person’s HIV has mutations that make antiretroviral drugs less effective. It’s done on a blood sample and uses genotypic (detects resistance-related mutations) or phenotypic (measures virus growth in the presence of drugs) methods. Results guide selection or change of antiretroviral therapy—commonly done before treatment, or if viral load rises.

At diagnosis before starting antiretroviral therapy to detect transmitted resistance; whenever virological failure or confirmed viral rebound occurs (usually viral load >200 copies/mL); before switching regimens or during pregnancy; if exposed to someone with known resistance; and after suspected PrEP/PEP or treatment failure. Repeat testing guides selection of an effective regimen.

Signs of HIV drug resistance include rising or persistently detectable viral load despite good adherence to antiretroviral therapy, failure of CD4 counts to rise or a decline in CD4 cells, clinical deterioration or new/recurrent opportunistic infections, and lack of viral suppression after starting or changing treatment. Resistance is confirmed by genotypic or phenotypic testing.

HIV‑1 positive means a person is infected with human immunodeficiency virus type 1, which attacks CD4 immune cells. It’s diagnosed by antibody/antigen or nucleic acid tests and transmitted through blood, sexual contact, or perinatally. Antiretroviral therapy (ART) controls viral replication, preserves immunity, prevents progression to AIDS, and—when viral load is undetectable—greatly reduces transmission risk.

T1 and T2 are test lines on some rapid HIV assays: C is the control line; T1 typically indicates a reactive result for HIV‑1 and T2 for HIV‑2. If only the control (C) appears, the test is negative; if T1 and/or T2 appear with C, the result is reactive and requires laboratory confirmatory testing. If the control line is absent, the test is invalid.