Prevalence of Transmitted Drug Resistance to Tenofovir, Emtricitabine in Newly Diagnosed HIV Infection

Positive HIV (human immunodeficiency virus) blood test results, computer illustration.
Investigators conducted a retrospective molecular epidemiologic study to assess transmitted drug resistance in patients recently diagnosed with HIV infection.

The prevalence of transmitted drug resistance seems to be decreased in patients with newly diagnosed HIV infection who are treated with tenofovir/emtricitabine, according to study results published in BMC Infectious Diseases.

A team of investigators in China conducted a retrospective molecular epidemiologic study to analyze transmitted drug resistance in patients with newly diagnosed HIV infection between 2016 and 2018.

A total of 2167 HIV pol ribonucleic acid sequences were acquired; 70.9% were subtype CRF01_AE, 18.0% were subtype CRF07_BC, 4.7% were subtype b, 2.6% were other subtypes, and 3.8% were unique recombinant forms. Of the cases with determined subtypes, 93.9% of patients were men. Of the cohort, the median age was 34 years, 63.1% of patients were unmarried, 49.6% had a college education or higher degree, and 83.6% were men who had sex with men.

Drug-resistant mutations were found in 4.9% of sequences.  Mutations resistant to protease inhibitors, nucleoside reverse transcription inhibitors, and non-nucleoside reverse transcriptase inhibitors were noted in 1.0%, 0.5%, and 2.8% of all sequences, respectively. Of these mutations, 0.6% of sequences were resistant to tenofovir/emtricitabine (10 CRF01_AE strains, 2 CRF07_BC strains, and 1 subtype B strain).

Mutations of K65R, which are known to present high-level resistance to tenofovir and intermediate-level resistance to emtricitabine, were found in 8 of the 13 sequences that were resistant to tenofovir/emtricitabine. Of these 13 cases of transmitted drug resistance, 23.1% of patients were estimated to have been infected within the past 6 months.

“The most important question arising from [transmitted drug resistance] transmission is whether [pre-exposure prophylaxis] will protect the individuals who are exposed to HIV strains with [drug-resistant mutations] against [tenofovir/emtricitabine],” the authors noted.

“The low prevalence and few phylogenetic link of HIV [transmitted drug resistance] in Shenyang suggested that the impact of [transmitted drug resistance] on the ongoing [pre-exposure prophylaxis] project is very limited. However, the overall prevalence of HIV [transmitted drug resistance] was close to 5% in Shenyang, highlighting the need for regular [transmitted drug resistance] monitoring to prevent the further spread of HIV [transmitted drug resistance] strains,” the investigators concluded.


Wang Z, Zhao B, An M, et al. Transmitted drug resistance to tenofovir/emtricitabine among persons with newly diagnosed HIV infection in Shenyang city, Northeast China from 2016 to 2018. BMC Infect Dis. 2021;21(1):668. doi:10.1186/s12879-021-06312-3