Objective:To investigate the prevalence of pretreatment drug resistance and the genetic polymorphism of CRF08_BC strains among HIV-1 patients in China.Methods:This cross-sectional survey involved the plasma samples of HIV patients in a national pretreatment HIV drug resistance survey conducted in 2018. RNA was extracted from the samples. The fragments containing protease and partial reverse transcriptase (PR/RT) regions were obtained and sequenced. Drug resistance was analyzed using Stanford HIVdb Program. Differences in polymorphic mutations between drug-resistant and non-drug-resistant HIV-1 strains were analyzed by Chi-square test or Fisher′s exact test. The association between drug-resistant and polymorphic mutations was evaluated using CorMut R package. Molecular transmission networks were constructed using HIV-TRACE software. Results:Totally 465 partial pol sequences were obtained from individuals with CRF08_BC infection in 25 provinces and cities. The total pretreatment drug resistance rate was 17.8% (83/465). The pretreatment drug resistance rates to non-nucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitors (PIs) were 16.6% (77/465), 1.1% (5/465) and 0.9% (4/465), respectively. The resistance rate to rilpivirine (RPV) was the highest (15.7%, 73/465). The most common mutation was E138A (11.6%, 54/465). There were six polymorphic mutations (S162C, K102Q, T200A, V179E, I202V, T200M) that co-variated with E138A. The molecular transmission network showed that patients infected with CRF08_BC strains carrying the resistant mutations at position E138 mainly gathered in clusters in Yunnan and Sichuan, and the highest degree of connection was in Lincang, Yunnan. Conclusions:In China, HIV-1 CRF08_BC-infected patients showed a high rate of pretreatment resistance to one of the second-generation NNRTIs, namely RPV. Further researches were warranted to evaluate the impacts of co-mutations of the E138A mutation and polymorphic sites on HIV resistance and replicative capacity.

Objective:To explore the resistance to protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and integrase inhibitors (INSTIs) of HIV-1 CRF55_01B and the transmission of drug-resistant strains among HIV-1 CRF55_01B infected patients before antiviral treatment in China.Methods:HIV-1 RNA was extracted from plasma samples of the patients infected with CRF55_01B in the national surveillance of HIV drug resistance before antiviral treatment in 2018. A 1 056 bp gene fragment of protease/reverse transcriptase (PR/RT) region and an 846 bp gene fragment of integrase (IN) region were obtained and sequenced. Drug resistance was analyzed by using all drugs included in the Stanford University HIV db Program, HIV-1 molecular network analysis was performed with software HIV-TRACE and polymorphism mutations of CRF55_01B integrase gene region were analyzed.Results:A total of 178 samples from 26 provinces, municipalities and autonomous regions in China were analyzed, and 170 sequences of CRF55_01B PR/RT region and 170 sequences of IN region of corresponding samples were obtained. The drug resistance rate was 15.3% (26/170). The drug resistance rates of PIs, NRTIs, NNRTIs and INSTIs were 1.2% (2/170), 1.2% (2/170), 15.3% (26/170), 0.6% (1/170), respectively. The level of drug resistance was mostly low. NNRTIs drug resistance mutations were mainly V179D/E co-appeared with other mutations, and 84.1% (143/170) of the infected patients carrying V179D/E alone showed potential drug resistance. INSTIs drug resistance mutation was G163R, and showed low resistance to EVG and RAL. The molecular network access rate was 30.0%(51/170)according to the 0.9% gene distance threshold. The resistant strains were transmitted between men with homosexual transmission and heterosexually transmitted people, and both carried resistant mutations E138G and V179E. In the integrase region, CRF55_01B and CRF01_AE and B subtypes showed high mutation frequency difference in 5 sites (T215A、G134N、I135V, K136R and L101I/V).Conclusions:Before antiviral treatment, CRF55_01B infected patients in China had a high resistance to NNRTIs. Strains carrying both E138G and V179E resistance mutations were transmitting in clusters. The prevalence of CRF55_01B integrase inhibitor resistant strains is low, but some genetic polymorphisms with high mutation rate in the integrase gene region have potential influence on drug sensitivity. The influence of drug resistance of new recombinant strains on antiviral therapy in China needs to be further monitored and analyzed.

Objective: To explore HIV-1 drug resistance and influencing factors among people living with HIV/AIDS before antiretroviral therapy in Liangshan Yi Autonomous Prefecture (Liangshan). Methods: Between January 1 and June 30, in both 2017 and 2018, a cross-sectional survey was conducted in Liangshan HIV-1 pol sequences were gathered and analyzed according to WHO Guidelines on HIV drug resistance surveillance of 2014. Both HyPhy 2.2.4 and Cytoscape 3.6.1 software were used to analyze the drug resistant strains of HIV-1 transmission network. Results: A total of 464 people living with HIV/AIDS was recruited. The proportion of HIV-1 CRF07_BC subtype was 88.6% (411/464), with HIV-1 drug resistance rate was 9.9% (46/464). The HIV-1 drug resistance rates of non-nucleoside reverse transcriptase inhibitors (NNRTI), nucleoside reverse transcriptase inhibitors(NRTI) and protease inhibitors (PI) were 6.7% (31/464), 1.9% (9/464) and 0.4% (2/464) respectively. New recombinant strains of HIV-1 URF_01BC subtype was independently clustered according to the drug resistant mutation sites. Results from the multivariate logistic analysis showed that injected drug users group had higher risk on HIV-1 drug resistance (aOR=3.03, 95%CI:1.40-6.54) than heterosexual group among people living with HIV/AIDS. Conclusions HIV-1 drug resistance rate had already been in a high level before antiretroviral therapy was in place. The newly identified recombinant strains of HIV-1 URF_01BC subtype were independently clustered according to the drug resistant mutation sites. It was necessary to strengthen the prevention of the HIV-1 drug resistant strains transmission.