Colorimetric detection and typing of E. coli lipopolysaccharides based on a dual aptamer-functionalized gold nanoparticle probe.

A rapid method for identification and typing of lipopolysaccharides (LPS) was developed by utilizing the different binding affinities between two kinds of gold nanoparticles (AuNPs) functionalized with two aptamers. Aptamers against ethanolamine and E. coli O111:B4 LPS were used to functionalize the AuNPs. The AuNPs functionalized with ethanolamine aptamer can bind to ethanolamine and are termed general probe (G-probe). The G-probe can recognize any type of LPS because ethanolamine is a component of every type of LPS. This causes a sandwich-mediated aggregation of the AuNPs and a color change from red to blue. The AuNPs functionalized with aptamer against the LPS of E. coli O111:B4 specifically bind to O111:B4 LPS and are termed specific probe (S-probe). By using these two probes, a logic typing method was developed. It can detect LPS in concentrations between 2.5 and 20 µg·mL-1 and with a 1 µg·mL-1 detection limit. In the authors' perception, the use of a dual aptamer-based colorimetric method has a large potential in terms of selective detection of microorganisms. Graphical abstract Two aptamer functionalized AuNP probes, G-probe and S-probe, were prepared for LPS typing and detecting. E. coli O111:B4 LPS was easily distinguished from O55:B5 LPS according to the signal output configurations (On & On Vs On & Off) of a general probe (G-probe) and a specific probe (S-probe).

Antiretroviral therapy to prevent HIV transmission in serodiscordant couples in China (2003-11): a national observational cohort study.

BACKGROUND: On the basis of the results of the randomised clinical trial HPTN 052 and observational studies, WHO has recommended that antiretroviral therapy be offered to all HIV-infected individuals with uninfected partners of the opposite sex (serodiscordant couples) to reduce the risk of transmission. Whether or not such a public health approach is feasible and the outcomes are sustainable at a large scale and in a developing country setting has not previously been assessed. METHODS: In this retrospective observational cohort study, we included treated and treatment-naive HIV-positive individuals with HIV-negative partners of the opposite sex who had been added to the national HIV epidemiology and treatment databases between Jan 1, 2003 and Dec 31, 2011. We analysed the annual rate of HIV infection in HIV-negative partners during follow-up, stratified by treatment status of the index partner. Cox proportional hazards analyses were done to examine factors related to HIV transmission. FINDINGS: Based on data from 38,862 serodiscordant couples, with 101,295·1 person-years of follow-up for the seronegative partners, rates of HIV infection were 2·6 per 100 person-years (95% CI 2·4-2·8) among the 14,805 couples in the treatment-naive cohort (median baseline CD4 count for HIV-positive partners 441 cells per µl [IQR 314-590]) and 1·3 per 100 person-years (1·2-1·3) among the 24,057 couples in the treated cohort (median baseline CD4 count for HIV-positive partners 168 cells per µl [62-269]). We calculated a 26% relative reduction in HIV transmission (adjusted hazard ratio 0·74, 95% CI 0·65-0·84) in the treated cohort. The reduction in transmission was seen across almost all demographic subgroups and was significant in the first year (0·64, 0·54-0·76), and among couples in which the HIV-positive partner had been infected by blood or plasma transfusion (0·76, 0·59-0·99) or heterosexual intercourse (0·69, 0·56-0·84), but not among couples in which the HIV-positive partner was infected by injecting drugs (0·98, 0·71-1·36). INTERPRETATION: Antiretroviral therapy for HIV-positive individuals in serodiscordant couples reduced HIV transmission across China, which suggests that the treatment-as-prevention approach is a feasible public health prevention strategy on a national scale in a developing country context. The durability and generalisability of such protection, however, needs to be further studied. FUNDING: Chinese Government's 12th Five-Year Plan, the National Natural Science Foundation of China, and the Canadian International Development Research Centre.

Highly sensitive detection of lipopolysaccharides using an aptasensor based on hybridization chain reaction.

Lipopolysaccharides (LPS), integral components of the outer membrane of all gram-negative bacteria, are closely associated with foodborne diseases such as fever, diarrhea and hypotension, and thus, the early and sensitive detection of LPS is necessary. In this study, an aptasensor assay based on hybridization chain reaction (HCR) was developed to detect LPS. Briefly, two complementary stable species of biotinylated DNA hairpins coexisted in solution until the introduction of a detection probe triggered a hybridization chain reaction cascade. The DNA conjugates specifically reacted with the LPS, which were captured by the ethanolamine aptamer attached to the reaction well surface. After optimizing the key reaction conditions, such as the reaction time of HCR, the amount of the capture probe and detection probes, the increase in the LPS concentration was readily measured by the optical density value, and a relatively low detection limit (1.73 ng/mL) was obtained, with a linear response range of 1-10(5 )ng/mL. The approach presented herein introduced the use of an aptasensor for LPS discrimination and HCR for signal amplification, offering a promising option for detecting LPS.

Molecular linkage tracing of HIV-1 transmission events in seroconcordant couples in Guangxi Province, Southeastern China.

BACKGROUND: Guangxi Province in Southeastern China has one of the highest HIV-1 infection and transmission rates in stable couples. However, the mode of transmission at the molecular level has seldom been reported amongst this group. It is important to investigate this issue to support the treatment-as-prevention approach and for efficient interventions. METHODS: HIV-1 subgenomic regions (1.2 kb of pol and a 660-bp env C2V5 fragment) were sequenced in 42 couples. A couple linkage assessment was performed by phylogenetic analysis of sequences and Bayesian analysis of genetic distances. A subset of pairs was selected for single-genome amplification. RESULTS: Thirty-five pairs (83.3 %, 35/42) were identified as linked, 3 pairs (7.1 %, 3/42) were identified as indeterminate, and 4 pairs (9.5 %) were identified as unlinked. The predominant intra-couple-transmitted HIV-1 subtype was CRF01_AE (80 %, 28/35). The median genetic distance of linked couples was 0.5 %. CONCLUSION: The majority of HIV-1 transmission events in this study occurred within the partnership, and the predominant HIV-1 subtype was CRF01_AE. Further research on the mode of HIV transmission in other locations is needed.

Assessment of Different Intervention Models of Male Circumcision and Their Preliminary Effectiveness in Reducing HIV Incidence Among Drug Users in Western China.

World Health Organization (WHO) and Joint United Nations Program on AIDS (UNAIDS) recommend male circumcision (MC) as an additional HIV prevention measure. This study aimed to assess three models of promoting MC and their effects on preventing HIV infection among drug users in western China. We carried out a cohort study in three provinces of western China. HIV seronegative male drug users were recruited from methadone maintenance therapy clinics and cluster randomized into three intervention models. At baseline, 6, and 9 months of follow-up, changes in MC knowledge, the acceptability of MC, MC surgery uptake, and the costs of model implementation were analyzed. Of 1,304 male drug users who were screened, 1,218 were enrolled in the study. The participants' knowledge about MC was significantly increased after interventions by all three models. The one-stage model led to the highest increase in MC acceptability and the greatest increase in MC uptake. Multivariable Cox regression analysis showed that the one-stage model was also the most effective method to promote MC uptake, compared with the two-stage model [rate ratio (RR) = 0.602; 95% confidence interval (CI), 0.420-0.862] and three-stage model (RR = 0.555; 95% CI, 0.382-0.807). The HIV incidence rate in the MC group was lower than that in the non-MC group (RR = 0.234; 95% CI, 0.056-0.974). Moreover, the one-stage model required the lowest cost per circumcision. The one-stage model is the most effective and the most cost-effective intervention to increase MC uptake among male drug users in western China and could decrease the HIV incidence rate, based on a short follow-up investigation.

HIV pre-exposure prophylaxis interest among female sex workers in Guangxi, China.

OBJECTIVES: Acceptability of pre-exposure prophylaxis (PrEP) and willingness to participate in a clinical trial for both safety and efficacy of PrEP were investigated among female sex workers (FSWs) in Guangxi, China. METHODS: A cross-sectional study was performed in three cities in Guangxi. Structured, self-administered questionnaires were used to assess the acceptability of PrEP and the willingness to participate in a clinical trial. Multivariable logistic regression models were fitted to identify predictors. RESULTS: Among 405 participants, 15.1% had heard of PrEP. If PrEP was deemed to be effective, safe and provided for free, 85.9% reported that they would accept it, and 54.3% of those who accepted PrEP said that they would participate in a clinical trial. The increased acceptability of PrEP was associated with working in male dominated venues, higher income, a poor family relationship, better HIV/AIDS knowledge, not realizing HIV risk from unfamiliar clients, not being forced to use condoms by the gatekeepers, consistent use of condoms, and use of drugs to prevent STD infection. The increased willingness to participate in a clinical trial was associated with a poor family relationship, better HIV/AIDS knowledge, not realizing HIV risk from unfamiliar clients, a willingness to adhere to daily PreP use, and not being concerned about discrimination by others. The main reason for rejecting PrEP or participating in a clinical trial was the concern about the side effects of PrEP. CONCLUSIONS: Acceptability of PrEP among Guangxi FSWs is relatively high, indicating that PrEP intervention programs may be feasible for Chinese FSWs. Given the fact that most of the participants had never heard of PrEP before, and that family, gatekeepers, and social discrimination could significantly affect its acceptability, a comprehensive mix of multiple interventions is necessary for the successful implementation of a PrEP program among this population in Guangxi.

HIV infection among new synthetic drug abusers: a pilot study in Beijing.

BACKGROUND: Following the increased human immunodeficiency virus (HIV) notification (infection) rates via sexual transmission and increased abuse of new synthetic drugs instead of heroin in China, a study on HIV infections and risk factors among synthetic drugs and heroin users in Beijing was conducted to provide a cue for further development of targets and strategies of HIV/AIDS control and prevention for different drug populations. METHODS: A total of 428 subjects including 224 heroin users and 204 new synthetic drug users was recruited from communities in Beijing by convenience sampling. A χ(2) test was used to compare HIV and syphilis infections between the two subpopulations. Logistic regression models were used to evaluate factors related to HIV, syphilis infections and abuse of synthetic drugs. RESULTS: Unbalanced distributions of demographics were detected between the two subpopulations. Compared with heroin users, most users of synthetic drugs were migrants, single and of younger age (age ≤ 30 years). Ten HIV infections and twenty-four syphilis infections were confirmed among 428 subjects. No significant difference in HIV infection was found between the two subpopulations (crude odds ratio (OR) = 0.46, 95% confidence interval (CI): 0.07 - 15.80 and adjusted odds ratio (AOR) = 1.26, 95%CI: 0.09 - 18.28) while four times as many syphilis infections were identified among users of synthetics drugs (AOR = 3.92, 95%CI: 1.06 - 14.56). HIV and syphilis infections appeared to work synergistically. The migrants who were of Han ethnicity, single and who had stayed in Beijing for more than six months were more likely to abuse synthetics drugs. CONCLUSIONS: The new synthetic drug users and heroin users are different subpopulations. We optimistically speculate that HIV has not yet been introduced into the former in Beijing, but considering higher syphilis infections in synthetic drug users and the role of syphilis in HIV infection, synthetic drug users, as a possible and important driver of the HIV/AIDS epidemic in Beijing, should be paid more attention in HIV prevention and control strategies.

Prevalence and correlates of sexual risk behaviors among drug users in western China: implications for HIV transmission.

The prevalence and correlates of sexual risk behaviors among drug users in western China and the implications for HIV transmission in this population are described. A cross-sectional survey of male drug users was conducted in methadone maintenance therapy clinics and detoxification centers in three western provinces of China between September 2009 and December 2010. Participants in the study completed a questionnaire about demographics, HIV/AIDS knowledge, drug use history, sexual risk behaviors, and other psychosocial variables. Factors associated with HIV sexual risk behaviors were identified by multiple logistic regression analysis. Of 1,304 drug users surveyed, nearly 54% never used condoms during sexual intercourse with a spouse or cohabitant, and this behavior was associated with coming from Chongqing (OR=1.86, p<0.05), being aged 36 and older (OR=5.03, p<0.05), being married or cohabiting (OR=1.68, p<0.05), having first taken drugs at age 30 and above (OR=1.80, p<0.05), and having received AIDS advice or detection from authorities in the past year (OR=1.95, p<0.05). Twenty-six percent had had sex with casual sexual partners in the past year, and this behavior was associated with being married or cohabiting (OR=0.30, p<0.05), first taking drugs at age 31 and above (OR=0.42, p<0.05), and receiving AIDS advice or HIV detection from authorities in the past year (OR=0.70, p<0.05). About 34% never used a condom when having sex with casual sexual partners, and this behavior was associated with coming from Guangxi (OR=2.81, p<0.05) or Chongqing (OR=2.73, p<0.05). Almost 14% had had commercial sex in the past year, and this behavior was associated with coming from Guangxi (OR=6.26, p<0.05) or Chongqing (OR=5.44, p<0.05) and having exchanged needles or received clean needles from the Needle Exchange Centers in the past year (OR=2.76, p<0.05). Nearly 23% had never used condoms when having commercial sex, and this behavior was associated with having received free condoms from authorities in the past year (OR=0.26, p<0.05). Sexual risk behaviors among drug users in Guangxi, Chongqing, and Xinjiang are common. Additional intervention strategies are needed to control the spread of HIV in this population.

Comparison of three intervention models for promoting circumcision among migrant workers in western China to reduce local sexual transmission of HIV.

OBJECTIVE: Three models for promoting male circumcision (MC) as a preventative intervention against HIV infection were compared among migrant worker populations in western China. METHODS: A cohort study was performed after an initial cross-sectional survey among migrant workers in three provincial level districts with high HIV prevalence in western China. A total of 1,670 HIV seronegative male migrants were cluster-randomized into three intervention models, in which the dissemination of promotional materials and expert- and volunteer-led discussions are conducted in one, two, and three stage interventions. Changes in knowledge of MC, acceptability of MC, MC surgery uptake, and the costs of implementation were analyzed at 6-month and 9-month follow-up visits. RESULTS: All three models significantly increased the participants' knowledge about MC. The three-stage model significantly increased the acceptability of MC among participants and led to greatest increase in MC uptake. At the end of follow-up, 9.2% (153/1,670) of participants underwent MC surgery; uptake among the one-, two-, and three-stage models were 4.9%, 9.3%, and 14.6%, respectively. Multivariable Cox regression analysis showed that three-stage model was the most effective method to scale up MC, with RR = 2.0 (95% CI, 1.3-3.1, P=0.002) compared to the on-site session model. The two-stage intervention model showed no significant difference with either the on-site session model (RR=1.5, 95% CI, 0.92-2.4, P=0.12) or three-stage model (P=0.10). CONCLUSIONS: A three-stage intervention with gradual introduction of knowledge led to the significantly increase in MC uptake among migrant workers in western China, and was also the most cost-effective method among the three models.

Acceptance of male circumcision among male rural-to-urban migrants in western China.

To describe the acceptability of male circumcision (MC) and explore potential factors associated with MC acceptability among male rural-to-urban migrants in western China, a cross-sectional survey of MC acceptability was conducted with 1,904 subjects in three western provinces with high HIV prevalence (Guangxi, Chongqing, and Xinjiang) in China between June 2009 and November 2009. Through face-to-face interviews, the participants completed a self-administered questionnaire about demographics, MC knowledge, willingness and reasons to accept or refuse MC, sexual behaviors, and other psychosocial variables. Factors associated with acceptability of MC were identified by multiple logistic regression analysis. Of the participants (n=1,904), 710 men were willing to accept MC (37.3%); the reasons included promotion of the partners' genital hygiene (54.9%), redundant prepuce or phimosis (43.1%), enhancement of sexual pleasure (40.6%), prevention of penile inflammation or cancer (35.5%), and protection against HIV and sexual transmitted diseases (STDs)(31.1%). A multivariable logistic regression showed that four factors were associated with acceptability of MC, including education level (OR=1.286, 95% CI=1.025~1.614), redundant prepuce or phimosis (OR=13.751, 95% CI=10.087~18.745), having one or more circumcised friends (OR=2.468, 95% CI=1.953~3.119), and having sexual intercourse with a temporary partner in the past year (OR=1.543, 95% CI=1.101~2.162). Compared with previously published data among the general population in China or worldwide, the acceptability of MC (37.3%) was low among the male rural-to-urban migrants in western China. Nevertheless, appropriate education could greatly improve the acceptability of MC. More public campaigns and health education on MC are needed to increase the rate of MC in China.

Factors influencing Chinese male's willingness to undergo circumcision: a cross-sectional study in western China.

BACKGROUND: Male circumcision (MC) has been shown to reduce the risk of female to male transmission of HIV. The goal of this survey was to explore the acceptability of MC among the Chinese and to identify factors associated with circumcision preference. METHODS: A cross-sectional survey was conducted between September 2009 and December 2010. We interviewed 2,219 male community participants, from three high HIV prevalence provinces in western China. A structured questionnaire was used to collect data on MC knowledge, willingness to accept MC, reasons to accept or refuse MC, and sexual behaviors and health. For those who refused MC, a health education intervention providing information on the benefits of circumcision was conducted. We used multiple logistic regression models to identify factors associated with the acceptability of MC. RESULTS: Of the respondents (n = 2,219), 44.6% (989/2,219) reported they would accept MC for the following reasons: promotion of female partners' hygiene (60.3%), redundant foreskin (59.4%), prevention of penile cancer (50.2%), enhanced sexual pleasure (41.4%), and protection against HIV and STDs (34.2%). The multivariable logistic regression showed that five factors were associated with MC willingness: long foreskin (OR = 15.98), residing in Xinjiang province (OR = 3.69), being younger than 25 (OR = 1.60), knowing hazards of redundant foreskin (OR = 1.78), and having a friend who underwent circumcision (OR = 1.36). CONCLUSION: The acceptability of male circumcision was high among the general population in China. Our study elucidates the factors associated with circumcision preference and suggests that more health education campaigns about positive health effects are necessary to increase the MC rate in China.

[Acceptability and influencing factors on pre-exposure prophylaxis programs among female sex workers in Guangxi, China].

OBJECTIVE: To study the acceptability of pre-exposure prophylaxis (PrEP) program on prevention of human immunodeficiency virus (HIV) infection among female sex workers (FSWs) in Guangxi of China. METHODS: A cross-sectional survey using convenience sampling was administered among 405 FSWs in Nanning, Liuzhou and Beihai cities of Guangxi, China. Self-designed questionnaire, face to face interviews were used to collect HIV-related risk behaviors, knowledge and acceptability of PrEP. RESULTS: After an introduction on PrEP, presuming that it was effective, safe and free of charge, 85.9% of the 405 FSWs said they would use it. Data from logistic regression analysis showed that significant factors of intent to use PrEP would include the followings: workplace (OR = 2.256, P = 0.009), monthly income (OR = 0.257, P = 0.004), family closeness (OR = 0.338, P = 0.012), knowledge on HIV/AIDS (OR = 2.802, P = 0.028), HIV/AIDS risk was introduced from a strange client (OR = 0.363, P = 0.049), whether the gatekeeper ordering the use of condom (OR = 0.432, P = 0.010), whether consistent using condom with clients (OR = 3.010, P = 0.002), whether ever using drugs to prevent STD infection (OR = 3.570, P = 0.049) etc. CONCLUSION: Awareness on HIV/AIDS knowledge and self-protection seemed the main influential factors while health education might promote the acceptability of PrEP.