HIV-1 Infection

HIV-1 infection is caused by a spherical, enveloped, single-stranded positive-sense RNA retrovirus that integrates its reverse-transcribed DNA into the host genome, leading to progressive immunodeficiency and AIDS. HIV-1, the predominant strain responsible for the global AIDS pandemic, is classified into three groups (M, O, N), with group M driving the epidemic and further subdivided into multiple subtypes (A–K) and circulating recombinant forms (CRFs) arising from co-infection. While subtype B is prevalent in North America and Europe, non-B subtypes and CRFs now account for over 90% of global infections, with increasing prevalence in the U.S. due to globalization. Advances in sequencing, particularly next-generation sequencing (NGS), have enhanced surveillance, detection, viral load monitoring, drug-resistance testing, and understanding of viral diversity, quasispecies dynamics, and transmission patterns, supporting more effective clinical management and public health strategies.