Functional Difference between N Domain and C Domain of hEGF and hTGF-alpha.

By exchanging the N domain and C domain of hEGF and hTGF-alpha genes by PCR, two chimeras E-TGF(EGF(1-32)-TGF-alpha(34-50))and T-EGF(TGF-alpha(1-33)-EGF(33-53))were constructed. The wild and chimeric molecules were expressed in E.coli under phoA system. The expressed hEGF, hTGF-alpha and two chimeras were purified. The EGF receptor competitive binding affinity of the four molecules was hEGF > hTGF-alpha and E-TGF > T-EGF and the cell proliferation stimulating activity of them was hTGF-alpha and E-TGF > T-EGF > hEGF. The result suggests that the N domain of hEGF and hTGF-alpha may play a major role in receptor binding activity and C domain of them may be responsible for stimulating cell proliferation.

Epidemiology of sexually transmitted infections, HIV, and related high-risk behaviors among female sex workers in Guangxi Autonomous Region, China.

This study assessed the epidemiology of sexually transmitted infections (STIs), HIV, and associated risk factors among female sex workers (FSWs) in Guangxi autonomous region, China. A cross-sectional study of 488 FSWs was conducted using a structured questionnaire to collect sociodemographic and behavioral information. Biological specimens from subjects were sampled to detect various STIs and HIV infection. Among FSWs, the prevalence rates of syphilis, Neisseria gonorrhoeae, Chlamydia trachomatis, genital herpes, condyloma acuminate, and HIV were 7.2%, 1.8%, 18.2%, 0.4%, 2.3%, and 0.8%, respectively. The prevalence rates of single, double, and triple infections were 22.3%, 3.9%, and 0.20%, respectively. Multivariate analysis indicated that STIs and HIV infection was independently related to low education level (OR = 7.244; 95% CI = 3.031-17.213; P < 0.001), low knowledge of STIs/HIV (OR = 0.191; 95% CI = 0.108-0.337; P < 0.001), low-grade working place (OR = 1.64; 95%CI = 1.016-2.648; P = 0.046), and no condom use during the last sexual intercourse (OR = 0.199; 95% CI = 0.113-0.350; P < 0.001). The prevalence of STIs is high among FSWs in Guangxi, is accompanied by a 0.8% HIV-positive rate, and may be largely related to high-risk sexual behaviors. Future interventions should be focused on the reduction of risk factors, including promotion of condom use and improvement of knowledge of STIs and HIV among FSWs.

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.

Risk of syphilis in STI clinic patients: a cross-sectional study of 11,500 cases in Guangxi, China.

OBJECTIVE: To measure prevalence of syphilis among the STI clinic population in Guangxi, China, and to assess the socioeconomic and behavioural characteristics associated with the infection. METHODS: We undertook a cross-sectional survey and syphilis and HIV serologic testing among 11 473 patients attending 14 community and hospital-based dermatovenereal clinics across eight cities in Guangxi between December 2004 and February 2006. RESULTS: 1297 (11.9%) patients demonstrated positive toludine red unheated serum test and Treponema pallidum particle agglutination results with serologic testing. A total of 58% (752) of seropositive subjects presented with a genital ulcer, palmar/plantar rash or inguinal lymphadenopathy. Female sex (OR = 2.23, 95% confidence intervals (CI) = 1.69 to 3.00, p<0.001), less education (middle school, OR = 1.70, 95% CI = 1.11 to 2.62, p = 0.023; primary school or less, OR = 1.98, 95% CI = 1.13 to 3.46, p = 0.017) and high annual income (OR = 1.91, 95% CI = 1.18 to 3.10, p = 0.009 for >30 000 RMB yuan) were associated with serologically positive status. Syphilis infection was significantly more prevalent in city 2 (19.5%, OR = 3.07, 95% CI = 1.83 to 5.16, p<0.001), city 4 (16.6%, OR = 1.90, 95% CI = 1.10 to 3.28, p = 0.011) and city 8 (13.8%, OR = 1.83, 95% CI = 1.13 to 2.97, p = 0.006). A total of 40.1% (532) of infected subjects engaged in commercial sex and increased rates of the infection was associated with multiple sexual partners (OR = 1.54, 95% CI = 1.16 to 2.06, p = 0.003). A total of 1.2% (133) of participants carried laboratory markers for HIV and 1.8% (23) of patients with syphilis were positive for HIV. CONCLUSIONS: Syphilis infection has reached alarming rates in China's STI clinic population, suggesting a generalised spread of the disease through commercial sex and bridging populations. Syphilis control is deserving of China's highest priority. Universal screening for syphilis and HIV testing in STI clinics should be considered as measures for control.

Polypyrimidine-tract-binding protein affects transcription but not translation of mouse hepatitis virus RNA.

Polypyrimidine-tract-binding protein (PTB) has been shown to bind specifically to the 5' ends of mouse hepatitis virus (MHV) RNA and its complementary strand. To further characterize the function of PTB in MHV replication, we generated dominant-negative mutant cell lines that express a full-length PTB or a truncated form of PTB, which includes only the N-terminal half of the protein, retaining its protein-dimerization domain. The truncated form of PTB was localized in the cytoplasm, whereas the full-length PTB was present mainly in the nucleus. The truncated form can interact with the full-length PTB in vitro. We observed that both the full-length and the truncated PTB, when overexpressed, functioned in a dominant-negative manner in MHV replication. However, the truncated form exhibited more severe effects on syncytia formation, virus production, and synthesis of viral RNA and viral proteins. To clarify the precise function of PTB in MHV replication, we dissociated the processes of viral transcription from translation by transfecting different types of MHV defective-interfering (DI) RNA that contain various reporter genes into these stable cell lines. Transcription of the DI RNA during MHV infection was greatly inhibited in these cell lines, indicating that PTB modulates MHV transcription. In contrast, translation of the DI RNA was not affected by PTB depletion in in vitro translation in rabbit reticulocyte lysate or by PTB overexpression in in vivo translation experiments in MHV-infected cells. Given that PTB interacts with the viral N protein, which is one of the components of the MHV replication complex, PTB may exert its function on viral replication/transcription by association with viral RNA as well as other viral and cellular factors in the replication complex.