PPR14 Interacts With PPR-SMR1 and CRM Protein Zm-mCSF1 to Facilitate Mitochondrial Intron Splicing in Maize.

In plants, splicing of organellar group II introns involves numerous nucleus-encoded trans-factors. But, how these trans-factors function and interact is not well understood. Here we report the function of a pentatricopeptide repeat (PPR) protein PPR14 and its physical relationship with other splicing factors in mitochondria. Null mutations of PPR14 severely arrest the embryo and endosperm development, causing an empty pericarp phenotype. PPR14 is required for the splicing of NADH dehydrogenase 2 (nad2) intron 3 and nad7 introns 1 and 2 in mitochondria. The absence of nad2 and nad7 transcripts leads to disruption of the mitochondrial complex I assembly and abolishes its NADH dehydrogenase activity. This is accompanied with increased levels of other mitochondrial complexes and elevated expression of the alternative oxidase proteins. As the function of PPR14 overlaps with PPR-SMR1 and the CRM-domain containing protein Zm-mCSF1, we tested their interactions. Protein-protein interaction analysis indicated that PPR14 interacts with PPR-SMR1 and Zm-mCSF1, suggesting that these three proteins may form a complex. As PPR proteins and CRM-domain containing proteins have many members in mitochondria and chloroplasts, we propose that organellar group II intron splicing is probably mediated by a dynamic complex that includes different PPR and CRM proteins in plants.

SMALL KERNEL4 is required for mitochondrial cox1 transcript editing and seed development in maize.

In land plants, cytidine-to-uridine (C-to-U) editing of organellar transcripts is an important post-transcriptional process, which is considered to remediate DNA genetic mutations to restore the coding of functional proteins. Pentatricopeptide repeat (PPR) proteins have key roles in C-to-U editing. Owing to its large number, however, the biological functions of many PPR proteins remain to be identified. Through characterizing a small kernel4 (smk4) mutant, here we report the function of Smk4 and its role in maize growth and development. Null mutation of Smk4 slows plant growth and development, causing small plants, delayed flowering time, and small kernels. Cloning revealed that Smk4 encodes a new E-subclass PPR protein, and localization indicated that SMK4 is exclusively localized in mitochondria. Loss of Smk4 function abolishes C-to-U editing at position 1489 of the cytochrome c oxidase1 (cox1) transcript, causing an amino acid change from serine to proline at 497 in Cox1. Cox1 is a core component of mitochondrial complex IV. Indeed, complex IV activity is reduced in the smk4, along with drastically elevated expression of alternative oxidases (AOX). These results indicate that SMK4 functions in the C-to-U editing of cox1-1489, and this editing is crucial for mitochondrial complex IV activity, plant growth, and kernel development in maize.

PPR20 Is Required for the cis-Splicing of Mitochondrial nad2 Intron 3 and Seed Development in Maize.

Pentatricopeptide repeat (PPR) proteins are helical repeat RNA-binding proteins that function in RNA processing by conferring sequence-specific RNA-binding activity. Owing to the lethality of PPR mutants, functions of many PPR proteins remain obscure. In this study, we report the function of PPR20 in intron splicing in mitochondria and its role in maize seed development. PPR20 is a P-type PPR protein targeted to mitochondria. The ppr20 mutants display slow embryo and endosperm development. Null mutation of PPR20 severely reduces the cis-splicing of mitochondrial nad2 intron 3, resulting in reduction in the assembly and activity of mitochondrial complex I. The ppr20-35 allele with a Mu insertion in the N-terminal region shows a much weaker phenotype. Molecular analyses revealed that the mutant produces a truncated transcript, coding for PPR20ΔN120 lacking the N-terminal 120 amino acids. Subcellular localization revealed that PPR20ΔN120:GFP is able to target to mitochondria as well, suggesting the sequence diversity of the mitochondrial targeting peptides. Another mutant zm_mterf15 was also found to be impaired in the splicing of mitochondrial nad2 intron 3. Further analyses are required to identify the exact function of PPR20 and Zm_mTERF15 in the splicing of nad2 intron 3.

PPR-SMR1 is required for the splicing of multiple mitochondrial introns, interacts with Zm-mCSF1, and is essential for seed development in maize.

Group II introns are ribozymes that can excise themselves from precursor-RNA transcripts, but plant organellar group II introns have structural deviations that inhibit ribozyme activity. Therefore, splicing of these introns requires the assistance of nuclear- and/or organellar-encoded splicing factors; however, how these splicing factors function remains unclear. In this study, we report the functions and interactions of two splicing factors, PPR-SMR1 and Zm-mCSF1, in intron splicing in maize mitochondria. PPR-SMR1 is a SMR domain-containing pentatricopeptide repeat (PPR) protein and Zm-mCSF1 is a CRM domain-containing protein, and both are targeted to mitochondria. Loss-of-function mutations in each of them severely arrests embryogenesis and endosperm development in maize. Functional analyses indicate that PPR-SMR1 and Zm-mCSF1 are required for the splicing of most mitochondrial group II introns. Among them, nad2-intron 2 and 3, and nad5-intron 1 are PPR-SMR1/Zm-mCSF1-dependent introns. Protein interaction assays suggest that PPR-SMR1 can interact with Zm-mCSF1 through its N-terminus, and that Zm-mCSF1 is self-interacting. Our findings suggest that PPR-SMR1, a novel splicing factor, acts in the splicing of multiple group II introns in maize mitochondria, and the protein-protein interaction between it and Zm-mCSF1 might allow the formation of large macromolecular splicing complexes.

SMK6 mediates the C-to-U editing at multiple sites in maize mitochondria.

The recently identified PPR-E+/NVWA/DYW2 RNA editing complex provides insights into the mechanism of RNA editing in higher plant organelles. However, whether the complex works together with the previously identified editing factors RIPs/MORFs is unclear. In this paper, we identified a maize Smk6 gene, which encodes a mitochondrion-targeted PPR-E+protein with E1 and E2 domains at the C terminus. Loss of Smk6 function affects the C-to-U editing at nad1-740, nad4L-110, nad7-739, and mttB-138,139 sites, impairs mitochondrial activity and blocks embryogenesis and endosperm development. Genetic and molecular analysis indicated that SMK6 is the maize ortholog of the Arabidopsis SLO2, which is a component of the PPR-E+/NVWA/DYW2 editing complex. However, yeast two-hybrid analyses did not detect any interaction between SMK6 and any of the mitochondrion-targeted RIPs/MORFs, suggesting that RIPs/MORFs may not be a component of PPR-E+/NVWA/DYW2 RNA editing complex. Further analyses are required to provide evidence that RIP/MORFs and SMK6 do not physically interact in vivo.

EMP18 functions in mitochondrial atp6 and cox2 transcript editing and is essential to seed development in maize.

RNA editing plays an important role in organellar gene expression in plants, and pentatricopeptide repeat (PPR) proteins are involved in this function. Because of its large family size, many PPR proteins are not known for their function and roles in plant growth and development. Through genetic and molecular analyses of the empty pericarp18 (emp18) mutant in maize (Zea mays), we cloned the Emp18 gene, revealed its molecular function, and defined its role in the mitochondrial complex assembly and seed development. Emp18 encodes a mitochondrial-localized DYW-PPR protein. Null mutation of Emp18 arrests embryo and endosperm development at an early stage in maize, resulting in embryo lethality. Mutants are deficient in the cytidine (C)-to-uridine (U) editing at atp6-635 and cox2-449, which converts a Leu to Pro in ATP6 and a Met to Thr in Cox2. The atp6 gene encodes the subunit a of F1 Fo -ATPase. The Leu to Pro alteration disrupts an α-helix of subunit a, resulting in a dramatic reduction in assembly and activity of F1 Fo -ATPase holoenzyme and an accumulation of free F1 -subcomplex. These results demonstrate that EMP18 functions in the C-to-U editing of atp6 and cox2, and is essential to mitochondrial biogenesis and seed development in maize.

The pentatricopeptide repeat protein EMP9 is required for mitochondrial ccmB and rps4 transcript editing, mitochondrial complex biogenesis and seed development in maize.

Pentatricopeptide repeat (PPR) proteins comprise a large family of sequence-specific RNA binding proteins in land plants. Because of its large family size and frequent embryo lethality in the mutants, molecular functions and physiological roles of many PPR proteins are unknown. Through characterization of an empty pericarp9 (emp9) mutant in maize (Zea mays), we defined the functions of EMP9 in mitochondrial RNA editing, respiratory complex formation and seed development. Mu insertions in different regions of Emp9 facilitated dissection of the domain functions of the EMP9. Through genetic and functional analyses of multiple alleles, we showed that deletions of two N-terminal PPR motifs and partial E+ domain do not eliminate the editing function of EMP9. Emp9 encodes an E+ subclass PPR protein that is localized in mitochondria. Loss of EMP9 function abolishes the C-to-U editing of ccmB-43 and rps4-335 sites in mitochondria. The loss of editing at ccmB-43 and rps4-335 affects the maturation of cytochrome c and impairs the biogenesis of mitochondrial respiratory complexes, particularly complex III. This work extends our understanding of PPR-E+ protein in editing function and seed development, and provides insights into the molecular function of mitochondrial CcmB protein in higher plants.

MiR-424 and miR-27a increase TRAIL sensitivity of acute myeloid leukemia by targeting PLAG1.

Although microRNAs have been elaborated to participate in various physiological and pathological processes, their functions in TRAIL resistance of acute myeloid leukemia (AML) remain obscure. In this study, we detected relatively lower expression levels of miR-424&27a in TRAIL-resistant and semi-resistant AML cell lines as well as newly diagnosed patient samples. Overexpression of miR-424&27a, by targeting the 3'UTR of PLAG1, enhanced TRAIL sensitivity in AML cells. Correspondingly, knockdown of PLAG1 sensitized AML cells to TRAIL-induced apoptosis and proliferation inhibition. We further found that PLAG1 as a transcription factor could reinforce Bcl2 promoter activity, causing its upregulation at the mRNA level. Both downregulated PLAG1 and elevated expression of miR-424&27a led to Bcl2 downregulation and augmented cleavage of Caspase8, Caspase3 and PARP in the presence of TRAIL. Restoration of Bcl2 could eliminate their effects on AML TRAIL sensitization. Overall, we propose that miR-424&27a and/or PLAG1 might serve as novel therapeutic targets in AML TRAIL therapy.

Outreach syphilis testing services by different health providers to female sex workers in southern China.

Health providers have played important roles on delivering prevention and care services to control syphilis in China. The current study was aimed to evaluate the performance of different health providers in providing outreach syphilis testing services to female sex workers (FSWs). The current study carried out during April to August 2009 in Liuzhou was aimed to investigate the services delivered by two different types of clinics in China. A total of 1,808 FSWs recruited from sex work venues were included in the study. Prevalence of positive syphilis test (6.4%) among FSWs accessed by the local center for disease control outreach teams (CDC teams) was significantly lower than that (9.3%) among FSWs accessed by the local reproductive health hospital outreach teams (RHH teams). As compared with CDC teams, RHH teams had more FSWs to be successfully referred to the designated STD clinics for further syphilis confirmation and intervention (85.7% vs. 26.7%, P<0.001). These findings indicate that RHH teams may be more efficient than CDC teams to provide outreach-based services to FSWs. Participation of the reproductive health providers or other medical facilities in outreach services to FSWs should be considered in developing intervention programs in China.

HIV prevalence varies between female sex workers from different types of venues in southern China.

We conducted a cross-sectional study on prevalence of human immunodeficiency virus (HIV) and syphilis among female sex workers (FSWs) recruited from different types of venues in 6 cities in China. Among 5322 FSWs (1379 were from high-tier venues, 2482 from middle-tier venues, and 1461 from low-tier venues, respectively), overall HIV prevalence was 0.54% (95% confidence interval [CI], 0.37%- 0.76%). By typology of venues where FSWs solicited clients, the prevalence was 1.37% (95% CI, 0.89%-2.11%) in low-tier venues, 0.28% (95% CI, 0.14%- 0.58%) in middle-tier venues, and 0.07% (95% CI, 0.01%-0.41%) in high-tier venues. The final logistic regression model showed an association of having had HIV infection with working in low-tier venues (adjusted odds ratio 2.73; 95% CI, 1.12-6.67) and coming from Guangxi Province (adjusted odds ratio, 7.89; 95% CI, 1.65-37.64). It can be concluded that FSWs working in low-tier venues (on the streets or public outdoor places) had higher risk of HIV infection than other venues. Such subgroup of FSWs should be efficiently covered by the current HIV/STD surveillance and intervention programs in China.

Risk factors for Mycoplasma genitalium infection among female sex workers: a cross-sectional study in two cities in southwest China.

BACKGROUND: Mycoplasma genitalium (MG) is one of the common causes of non-gonococcal urethritis (NGU) in men and is associated with cervicitis, endometritis, and pelvic inflammatory diseases (PID) in women. The prevalence of MG infection has been reported to be high among female sex workers (FSWs) in many countries, but limited information is known among this population in China. METHODS: From July to September 2009, venue-based FSWs were recruited in two cities (Wuzhou and Hezhou) of Guangxi Autonomous Region in southwest China. Information of socio-demographic and behavioral characteristics was collected by a questionnaire-based interview. Cervical specimens were obtained for detection of MG using a real-time polymerase chain reaction (PCR) assay targeting mgpA gene. RESULTS: The overall prevalence of MG infection among 810 FSWs was 13.2% (95% CI = 10.87%-15.52%). MG infection was significantly associated with less education (adjusted odds ratio (AOR) = 2.36, 95% CI = 1.15-4.87) consisting of junior high school or below, being single (AOR = 2.27, 95% CI = 1.42-3.62), migrant background (AOR = 2.03, 95% CI = 1.29-3.20), and absence of any STI symptoms in the previous year (AOR = 1.66, 95% CI = 1.09-2.52). CONCLUSIONS: MG infection was prevalent among FSWs in the study areas. This pattern of infection suggests that an increasing attention should be paid to MG screening and treatment in this high risk population.

Prevalence and risk factors of HSV-2 infection and HSV-2/HIV coinfection in men who have sex with men in China: a multisite cross-sectional study.

OBJECTIVES: To determine the prevalence and risk factors of herpes simplex virus type 2 (HSV-2) infection and its coinfection with human immunodeficiency virus (HIV) in men who have sex with men (MSM) in China. METHODS: A convenience sample of 1462 MSM were recruited from different settings (an STD clinic, a health center, and MSM venues) in 3 cities in China. Blood specimens were collected for testing for antibodies to HSV-2 and HIV to determinate the seroprevalence of HSV-2 infection and HSV-2/HIV coinfection. Information on sociodemographic and behavioral characteristics was collected to determine the risk factors associated with the infections. RESULTS: The prevalence of HSV-2 infection in 1462 MSM was 16.0% (95% confidence interval [CI], 14.2%-18.0%), the prevalence of HIV infection in this population was 9.5% (95% CI, 8.1%-11.1%), and the rate of coinfection of HSV-2 and HIV was 3.2% (95% CI, 2.4%-4.3%). Multivariate logistic regression analysis showed that risk factors for HSV-2 infection included age older than 30 years, education level lower than senior high school, involvement in commercial sex work, and HIV-positive status. Education level lower than junior high school and history of sexual abuse were associated with HSV-2/HIV coinfection. CONCLUSIONS: The high prevalence of HSV-2 infection and HSV-2/HIV coinfection among MSM in China suggests that an increased focus on HSV control is warranted within China's prevention and intervention programs targeted toward MSM.

Rapid syphilis testing uptake for female sex workers at sex venues in Southern China: implications for expanding syphilis screening.

BACKGROUND: Accessibility of syphilis testing services is critical in syphilis control programs for female sex workers (FSWs), but few FSWs attend public STI clinics or other testing sites. Introduction of free rapid syphilis testing (RST) into outreach programs for FSWs will help improve test uptake. METHODS: Commercial sex venues were identified in two cities in South China. In cooperation with health advocacy organizations, health outreach teams from local public health or medical facilities approached all types of sex venues in study areas to offer free RST. Acceptability and uptake of RST among FSWs were evaluated. RESULTS: A total of 2812 FSWs were offered RST and 2670 (95.0%) accepted syphilis testing. 182 (6.8%) FSWs had a positive RST result among whom 136 (74.7%) were willing to attend an STD clinic for confirmatory testing and treatment. More than half (89, 66.4%) of those with syphilis were not willing to notify their sex partners. Multivariate logistic analysis showed that syphilis test uptake was associated with residing in Jiangmen (AOR, 1.78; 95% CI, 1.15-2.77), older age (AOR, 2.11, 95% CI, 1.17-3.79 for age of 31 years or above), and not working at a service venue (AOR, 1.60; 95% CI, 1.10-2.34). CONCLUSIONS: RST at sex venues is well accepted by FSWs when it is integrated into ongoing outreach services. Such programs provide excellent opportunities for expanding syphilis screening efforts among specific subgroups of FSW who are difficult to reach through clinic-based programs.

Molecular typing of Treponema pallidum causing early syphilis in China: a cross-sectional study.

BACKGROUND: There have been limited data on molecular epidemiology of syphilis in China. This study aimed to analyze strain type distribution of Treponema pallidum causing early syphilis across geographic areas in China using an enhanced method. METHODS: Genital samples were collected from patients in East, South, and North China. Positive DNA of T. pallidum was analyzed by arp, tpr, and tp0548 genes. RESULTS: Sufficient DNA for full molecular typing existed in 197 of 324 samples, and 27 strain types were identified. A range of 3 to 20 repeats (except 4, 11, and 19 repeats) and 25 repeats were found for the 60-bp tandem repeats of the arp gene. This was the first time the 9 and 25 repeats were detected. For the RFLP analysis of the tpr genes, patterns a, d, h, j, and l were identified. This was the first time the h, j, and l patterns were observed in China. For the sequence analysis of the tp0548 gene, sequences c, e, and f were identified. Strain type distribution was significantly different across geographic areas (χ² = 20.6, P = 0.006). Overall, 14d/f was most predominant (39% of fully typed samples, 95% CI = 32%-46%); 13d/f, 15d/f, and 16d/f were next most common (each 13% of fully typed samples, 95% CI = 9%-18%). CONCLUSIONS: There is substantial genetic diversity of T. pallidum in China. The broad and ununiform distribution of strain types may reflect differences in regional sexual network patterns. Predominance of few strain types may indicate a linked transmission.

[Expression of interleukin-18 and interleukin-18 receptor alpha chain of the peripheral white blood cells in immune thrombocytopenia].

OBJECTIVE: To detect the expression of interleukin (IL)-18 of the peripheral blood cells and IL-18 receptor alpha chain (IL-18Ralpha) on the surface of CD(3)(+) cells in patients newly diagnosed as immune thrombocytopenia (ITP) before medication and to explore the roles of IL-18 and IL-18Ralpha in the development of ITP. METHODS: Eighteen out-patients or inpatients with acute ITP accepting treatment in Qilu Hospital were enrolled in this study and 15 matching healthy subjects were taken as control. Plasma IL-18 level was detected with enzyme linked immunosorbent assay (ELISA), the expression of IL-18Ralpha on CD(3)(+) lymphocytes and total lymphocytes were measured with flow cytometry;T-bet and GATA-3 mRNA were measured with reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: The expression of IL-18 in acute ITP plasma was (468.57 + or - 141.62) ng/L and IL-18Ralpha on the surface of CD(3)(+) cells and lymphocytes were (8.50 + or - 3.16)% and (9.16 + or - 2.98)% respectively. The levels of IL-18 and IL-18Ralpha were increased in active ITP patients as compared with those in the controls (P < 0.05). The levels of IL-18 mRNA (0.12 + or - 0.02) and T-bet mRNA (0.07 + or - 0.02) were significantly increased in patients with active ITP as compared with those in the controls (P < 0.05), while GATA-3 mRNA (0.0039 + or - 0.0014) were significantly decreased in patients with active ITP (P < 0.05). The balance between T-bet and GATA-3 was significantly disturbed in ITP. CONCLUSIONS: Through the variation of the levels of gene and protein, our study showed that IL-18 and IL-18Ralpha might upregulate the expression of Th1-cytokines in ITP patients. It is also suggested that IL-18 has potential association with the development of ITP. Especially, it may provide a new treatment method for ITP by regulating the ratio of T-bet and GATA-3 and resuming the balance of Th1/Th2.

Performance of serological tests for syphilis in sexually transmitted diseases clinics in Guangxi Autonomous Region, China: implications for syphilis surveillance and control.

BACKGROUND: China is experiencing a growing syphilis epidemic. Individuals are currently screened and cases are confirmed using traditional serological testing methods. METHODS: A total of 11 558 serum specimens from patients at 14 sexually transmitted diseases (STD) clinics at provincial, prefecture and county levels in Guangxi Autonomous Region were tested at local clinics using the toluidine red unheated serum test (TRUST) and the SD Bioline Syphilis 3.0 Treponema Pallidum (SD-TP) test and then transported to the National STD Reference Laboratory for TRUST and confirmatory Treponema pallidum particle assay (TPPA) testing. RESULTS: In local clinics, 13.2% of specimens were TRUST positive and 12.8% were TRUST and SD-TP positive. At the Reference Laboratory, 15.4% of specimens were TRUST positive and 11.8% were TRUST and TPPA positive. Local clinics showed a significantly higher prevalence of active syphilis compared with results from the Reference Laboratory (12.8 v. 11.8%, chi(2) = 4.59, P = 0.03). The local TRUST tests had consistent results with Reference Laboratory tests qualitatively among 96.2% of the specimens and quantitatively among 95.5% of the specimens. The algorithm of TRUST screening and then SD-TP confirmation among positive TRUST specimens at local STD clinics had 96.6% sensitivity and 99.3% specificity in diagnosing active syphilis compared with the 'gold standard' based on TRUST and TPPA positivity at the Reference Laboratory (positive predictive value 95.1% and negative predictive value 99.5%). CONCLUSION: The TRUST screening and SD-TP confirmation in combination can be used at local STD clinics for the efficient diagnosis of serologically active syphilis. However, continuing capacity building and quality assurance remain critical in ensuring the quality of syphilis diagnosis at local clinics.

Interleukin 18 and interleukin 18 binding protein in patients with idiopathic thrombocytopenic purpura.

To evaluate the balance of interleukin IL18 and its endogenous antagonist IL18 binding protein (IL18BP) in patients with idiopathic thrombocytopenic purpura (ITP), plasma IL18, IL18BP, interferon gamma (IFNG) and IL4 levels, as well as platelet counts were measured in patients with active ITP (n = 23), ITP in remission (n = 21) and in healthy subjects (n = 24) by enzyme linked immunosorbent assay (ELISA). Using real-time quantitative polymerase chain reaction, the mRNA expression of IL18, IL18BP, IFNG, IL4, T-box (TBX21) and GATA-binding protein 3(GATA3) were studied in all subjects. The results showed that IL18 and IFNG protein and mRNA levels were significantly increased in patients with active ITP than in control subjects, but that IL18BP were not significantly elevated in ITP patients, which resulted in an elevated ratio of IL18/IL18BP in patients with active disease. During remission stages, the levels of these cytokines were comparable to those of healthy controls. The elevated levels of IL18/IL18BP in plasma during active stages of disease suggest a possible role in the pathogenesis and course of ITP.

Opa typing of Neisseria gonorrhoeae strains isolated from patients attending sexually transmitted disease clinics in China.

BACKGROUND: Gonorrhoea has been one of the most common sexually transmitted diseases (STDs) in China. A clear understanding of its transmission dynamics is important in formulating prevention and control measures. GOAL: To investigate the distribution of opa types in patients attending at STD clinics in China and to evaluate the concordance between epidemiologic data and opa-typing results. STUDY DESIGN: Opa typing was conducted for 330 Neisseria gonorrhoeae strains isolated from the patients at 4 STDs clinics in China, and the epidemiologic data were collected as well. RESULTS: A total of 309 opa types were detected from the 330 isolates. Two hundred ninety-two opa types were unique, and 17 opa types were found in more than 1 patient. Opa typing confirmed all 9 sexual links that were revealed by epidemiologic information and further identified 9 opa clusters and 8 similar pairs. CONCLUSIONS: Opa typing is a discriminatory tool that can be used in epidemiologic studies on gonococcal infections. This technique is more powerful than epidemiologic data to identify sexual links and improve our understanding of the transmission dynamics of gonorrhoea.

Detection of Acute and Established HIV Infections in Sexually Transmitted Disease Clinics in Guangxi, China: Implications for Screening and Prevention of HIV Infection.

BACKGROUND: Human immunodeficiency virus (HIV) has spread throughout China and to some degree has penetrated the general heterosexual population in some regions. METHODS: A cross-sectional survey of 11,461 sexually transmitted disease (STD) clinic attendees in 8 cities in Guangxi, China, was conducted for syphilis and for acute and established HIV infections. RESULTS: The prevalence of acute and established HIV infections was 1.2% among the participants. Five acute (preseroconversion) HIV infections were detected. Multivariate analysis showed that HIV infection was independently related to unmarried status (odds ratio [OR], 1.73 [95% confidence interval {CI}, 1.00-2.99), less education (OR for less than primary school, 4.21 [90% CI, 1.21-14.58]), residence in city A (OR, 11.48 [95% CI, 2.05-64.31]) or city B (OR, 7.93 [95% CI, 1.75-35.91]), working in the entertainment industry (OR, 3.98 [95% CI, 1.14-13.88]), injection drug use (OR, 25.09 [95% CI, 10.43-60.39]), no condom use during most recent sexual intercourse (OR, 4.97 [95% CI, 1.38-17.88]), and syphilitic infection (OR, 1.91 [95% CI, 1.03-3.56]). CONCLUSIONS: HIV prevalence in STD clinics is significantly greater than that in the general population, and subjects were identified who would be missed by conventional surveillance. China's nationwide system of public STD clinics, which reach down to the township level, should be used for HIV control programs.