HIV Nucleic Acid Amplification Testing for Acute Infection Diagnosis

Clinical Context and Diagnostic Recommendations

The Centers for Disease Control and Prevention (CDC) recommends that when acute HIV infection is suspected, both a rapid or laboratory-based Ag/Ab test AND a diagnostic HIV NAT are performed at the initial medical visit 1, 2, 4
The American College of Physicians and the CDC suggest that baseline testing should include laboratory-based Ag/Ab testing plus NAT, especially if recent antiretroviral exposure occurred 1, 4
NAT is essential because antiretroviral medications can suppress viral load and delay seroconversion, decreasing detection ability 1, 2, 5
The CDC recommends nucleic acid testing for patients with suspected acute retroviral syndrome, as initial HIV antibody tests can be negative during acute infection 3

HIV nucleic acid amplification assay (NAT) can detect HIV infection 10-14 days after exposure, significantly earlier than antigen/antibody combination tests (18-45 days) and substantially earlier than antibody-only tests (3-12 weeks) 1, 2
Fourth-generation Ag/Ab combination tests detect HIV approximately 18-45 days post-infection 2
HIV-1/HIV-2 antibody differentiation assays are used as confirmatory tests after positive Ag/Ab screening, not for initial acute infection detection 1
Rapid HIV antibody tests detect HIV antibodies in at least 95% of patients within 6 months after infection, but are less sensitive than NAT programs 3

Early detection during acute infection is critical because persons with acute HIV are highly infectious 2
Suspicion of acute retroviral syndrome should prompt nucleic acid testing, as antibody-based tests will miss acute infections 3