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Updated: Feb 26, 2026
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Amplifying and Quantifying HIV-1 RNA in HIV Infected Individuals with Viral Loads Below the Limit of Detection by Standard Clinical Assays
Published on: September 26, 2011
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HIV-1 subtype diversity trends in a Northern California cohort
Kaiming Tao1, Philip L Tzou1, Malaya K Sahoo2
1Department of Medicine, Division of Infectious Diseases, Stanford University, Stanford.
AIDS (London, England)
|February 25, 2026
Summary
Non-B HIV subtypes are increasing in Northern California, indicating growing viral diversity. This trend highlights the need for ongoing monitoring of HIV epidemiology in the U.S.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Human Immunodeficiency Virus type 1 (HIV-1) subtype B has historically dominated the U.S. epidemic.
- Understanding the genetic diversity of circulating HIV-1 strains is crucial for effective prevention and treatment strategies.
- Emergence and spread of non-B subtypes can impact treatment efficacy and public health interventions.
Purpose of the Study:
- To analyze the trends and prevalence of HIV-1 subtypes, particularly non-B subtypes, in Northern California from 2000 to 2019.
- To assess the changing landscape of HIV-1 genetic diversity within a specific U.S. geographic region.
- To identify specific non-B subtypes that are increasing over time.
Main Methods:
- Retrospective analysis of HIV-1 resistance testing data.
- Inclusion of 9199 individuals tested by Stanford Healthcare Clinical Virology Laboratory between 2000 and 2019.
- Identification and quantification of HIV-1 subtypes, with a focus on non-B variants.
Main Results:
- Non-B HIV-1 subtypes were detected in 3.5% of individuals tested.
- The most prevalent non-B subtypes included CRF01_AE (1.0%), subtype C (1.0%), CRF02_AG (0.46%), and subtype A (0.45%).
- A significant increasing trend was observed for non-B viruses, notably CRF01_AE and CRF02_AG, over the study period.
Conclusions:
- While subtype B remains dominant, the increasing prevalence of non-B HIV-1 subtypes signifies growing viral diversity in the U.S. epidemic.
- The rise of specific non-B subtypes like CRF01_AE and CRF02_AG warrants continued surveillance and may have implications for treatment and prevention.
- These findings underscore the dynamic nature of the HIV epidemic and the importance of molecular surveillance.
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