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.

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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