Objective To investigate the subtype distribution and sequence characteristics of HIV-1 strains prevalent among sexual infectors in Beijing. Methods We collected the blood samples from 100HIV sexual infectors in Beijing during 2008 and separated plasma specimens. RNA was extracted from the plasma and the gag gene was amplified by RT-PCR and nest-PCR. The PCR products were sequenced directly and phylogenetic analyses of gag gene was performed using the MEGA4 software. Results Among 100 HIV-1 plasma samples,84 gag gene fragments were amplified and analyzed. Eight HIV subtypes including B(22 strains), B'(8 strains),C( 1 strain) ,CRF01_AE (38 strains) ,CRF02_AG (2 strains) ,CRF07_BC(9 strains) ,CRF08_BC(3 strains) and C/CRF01_AE recombinant like strain( 1 strain) were identified circulating in Beijing. Conclusion CRF01 _AE and subtype B were predominant in Beijing account for 45.2% and 26.2% and the surveillance of HIV gene variation should be paid more attention.

Objective To study the prevalence of HIV-1 drug-resistant strains in antiretroviral therapy-naive HIV-1 infectors,and provide background information for HIV-1 drug resistance survey and clin-ical antiretroviral therapy in Beijing in 2008. Methods Referring to the guidelines for HIV drug resistance threshold survey(HIVDR-TS) of WHO, collecting 60-70 plasma samples of HIV-1 infectors who were detec-ted in 6 months and not more than 25 years,we detected HIV-1 pol genotype and genetic mutations associated with drug resistance,counted the prevalence of drug-resistant strains, and evaluated the prevalent level. Re-Sults Of 61 plasma samples answering for the standards, 50 were successfully sequenced and genotyped pol sequence. The major infection route was homosex, which accounted for 62%. B, CRF01_AE, and CRF07_ BC were major genetic subtype, which accounted for 42%, 28% and 26%, respectively. One Pl-resistant strain was found, the incidence of which was 2% (1/50). One NRTI-resistant strain was found, the inci-dence of which was 2% (1/50). No NRTI-resistant strain was found, the incidence of which was 0. The in-cidence of drug-resistant strains in the protease (PR) region was 2%, and the incidence of reverse tran-scriptase (RT) region was also 2%. Both of the prevalence were classified as low level ( <5% ). Conclu-sion PR, RT-resistant HIV-1 strains were found in drug-naive infectors, and the prevalence was low in Beijing. Current antiretrovirai therapy regiments were still feasible. Most of the AIDS patients did not need to test drug resistance before antiretroviral therapy.

Objective To study the determination method of total flavonoids in Gansu Astragali Radix and Hedysarum Polybotrys. Methods Calycosin glycosides etc. was selected as reference substances, comparison on the difference of absorption curves was done by ultraviolet spectroscopy and colorimetric method (NaNO2-Al(NO3)3-NaOH, AlCl3, Mg(Ac)2, NaOH, phosphomolybdic acid, HCl-Mg power). Results With colorimetric method, the maximum absorption wavelength of referrence and the test was inconsistent. The absorption peak shape was also different. With UV method, Calycosin glycosides in band Ⅱ (260 nm) showed a shoulder absorption. Astragali Radix and Hedysarum Polybotrys also showed characteristic shoulder absorptions in band Ⅱ with absorption wavelength at 263 nm and 265 nm. So the sample absorption wavelength is basically the same as that of the control sample. Conclusion Colorimetries usually used for determination of total flavonoids are not suitable for the comparison determination of Gansu Astragali Radix and Hedysarum Polybotrys. It is suitable for determining the contents of total flavonoids in samples by UV spectrophotometry at the band Ⅱ, which is the characteristic absorption band of isoflavone compound.

Objective: To explore the intra-host genetic evolution of HIV-1 pol gene via follow-up for treatment-naïve HIV infections, and estimate the infection time with Bayesian coalescent theory, so as to support the evaluation of HIV epidemic. Methods: Five cases were recruited and followed up. The pol gene fragments were amplified for the characteristics of transmitted drug resistance ( TDR ) by RT-PCR. Bayesian coalescent theory was utilized to construct maximum clade credibility ( MCC ) tree for genetic evolution and calculate the time to the most recent common ancestor ( tMRCA ). Results: The five cases were all male, and aged from 27 to 50 years old.Five to nine sampling times were obtained from each case, and the pol gene sequences from each case formed a unique subcluster (posterior probability: 100% ), with different evolution characteristics, in the MCC tree. The three cases in primary HIV-1 infection were estimated to be infected one to five months before the first positive reaction of HIV screening, whereas the two HIV-1 diagnosed cases at first screening were extrapolated to get infected fourteen months and seven months before diagnosis, respectively. One case with acute HIV-1 infection carried TDR mutation ( M46I ) , expressing fast disease progress and quasispecies variation. Conclusions The general infection time can be estimated by analyzing the characteristics of intra-host genetic evolution of HIV-1 pol gene with Bayesian coalescent theory, and this method can help to estimate the HIV epidemic.