Transcription of TP0126, Treponema pallidum Putative OmpW Homolog, Is Regulated by the Length of a Homopolymeric Guanosine Repeat

An effective mechanism for introduction of phenotypic diversity within a bacterial population exploits changes in the length of repetitive DNA elements located within gene promoters. This phenomenon, known as phase variation, causes rapid activation or silencing of gene expression and fosters bacterial adaptation to new or changing environments. Phase variation often occurs in surface-exposed proteins, and in Treponema pallidum subsp. pallidum, the syphilis agent, it was reported to affect transcription of three putative outer membrane protein (OMP)-encoding genes. When the T. pallidum subsp. pallidum Nichols strain genome was initially annotated, the TP0126 open reading frame was predicted to include a poly(G) tract and did not appear to have a predicted signal sequence that might suggest the possibility of its being an OMP. Here we show that the initial annotation was incorrect, that this poly(G) is instead located within the TP0126 promoter, and that it varies in length in vivo during experimental syphilis. Additionally, we show that TP0126 transcription is affected by changes in the poly(G) length consistent with regulation by phase variation. In silico analysis of the TP0126 open reading frame based on the experimentally identified transcriptional start site shortens this hypothetical protein by 69 amino acids, reveals a predicted cleavable signal peptide, and suggests structural homology with the OmpW family of porins. Circular dichroism of recombinant TP0126 supports structural homology to OmpW. Together with the evidence that TP0126 is fully conserved among T. pallidum subspecies and strains, these data suggest an important role for TP0126 in T. pallidum biology and syphilis pathogenesis

Awareness and acceptance of HPV vaccination for condyloma acuminata among men who have sex with men in China

The dissemination of the fact that the human papillomavirus (HPV) vaccine can protect females as well as males is greatly beneficial for the control of condyloma acuminata (CA). We aimed to investigate the acceptance of the HPV vaccine for CA among men who have sex with men (MSM) in China. A cross-sectional online survey in the adult MSM population from 31 regions in China was carried out via WeChat in May 2017. Information on demographic characteristics, sexual behaviors, history of HIV and HPV infection, awareness of CA and HPV/CA vaccines, acceptance of CA vaccination, and behavioral intentions for vaccination were collected through a self-administered questionnaire. In total, 902 questionnaires were analyzed; the prevalence of CA was 13.3% (120/902), the HIV positivity rate was 15.1% (136/902), and the coinfection rate of HIV and CA was 3.9% (35/902). In the MSM population, the knowledge of CA and HPV/CA vaccines was poor, but the acceptance rate of the CA vaccine was high (85.1%, 768/902). Data indicated that MSM who had a history of anal intercourse (OR = 1.9), had heard of CA (OR = 2.9), knew the treatments for CA (OR = 2.0), had heard of HPV vaccines/cervical cancer vaccines (OR = 1.9), and received education about CA (OR = 1.9) were associated with the intention to use CA vaccines. With current moderate levels of CA and HPV/CA vaccine awareness, more emphasis should be placed on improving education and other behavioral interventions for high-risk populations such as MSM in China

<i>Treponema pallidum</i> subsp. <i>pallidum</i> TP0136 Protein Is Heterogeneous among Isolates and Binds Cellular and Plasma Fibronectin via its NH₂-Terminal End

<div><p>Adherence-mediated colonization plays an important role in pathogenesis of microbial infections, particularly those caused by extracellular pathogens responsible for systemic diseases, such as <i>Treponema pallidum</i> subsp. <i>pallidum</i> (<i>T</i>. <i>pallidum</i>), the agent of syphilis. Among <i>T</i>. <i>pallidum</i> adhesins, TP0136 is known to bind fibronectin (Fn), an important constituent of the host extracellular matrix. To deepen our understanding of the TP0136-Fn interaction dynamics, we used two naturally-occurring sequence variants of the TP0136 protein to investigate which region of the protein is responsible for Fn binding, and whether TP0136 would adhere to human cellular Fn in addition to plasma Fn and super Fn as previously reported. Fn binding assays were performed with recombinant proteins representing the two full-length TP0136 variants and their discrete regions. As a complementary approach, we tested inhibition of <i>T</i>. <i>pallidum</i> binding to Fn by recombinant full-length TP0136 proteins and fragments, as well as by anti-TP0136 immune sera. Our results show that TP0136 adheres more efficiently to cellular Fn than to plasma Fn, that the TP0136 NH2-terminal conserved region of the protein is primarily responsible for binding to plasma Fn but that binding sites for cellular Fn are also present in the protein’s central and COOH-terminal regions. Additionally, message quantification studies show that <i>tp0136</i> is highly transcribed during experimental infection, and that its message level increases in parallel to the host immune pressure on the pathogen, which suggests a possible role for this protein in <i>T</i>. <i>pallidum</i> persistence. In a time where syphilis incidence is high, our data will help in the quest to identify suitable targets for development of a much needed vaccine against this important disease.</p></div

<i>T</i>. <i>pallidum</i> subsp. <i>pallidum</i> strains used in this study.

<p>¹The Nichols Seattle strain was provided by James N. Miller, University of California, Los Angeles, CA. The Nichols Houston strain was provided by Steven J. Norris, University of Texas Health Science Center, Houston, TX. The Nichols Dallas strain was provided by Michael Norgard, University of Texas Southwestern Medical Center, Dallas, TX.</p><p>²Year refers to the isolation of the parent Nichols strain by HJ Nichols and WH Hough [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003662#pntd.0003662.ref068" target="_blank">68</a>].</p><p>³ The Dal-1 strain [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003662#pntd.0003662.ref069" target="_blank">69</a>] was provided by Rob George, CDC, Atlanta, GA</p><p>⁴Strains provided by Paul Hardy and Ellen Nell, Johns Hopkins University, Baltimore, MD.</p><p>⁵Strain isolated in Seattle by Sheila A. Lukehart, University of Washington, Seattle, WA.</p><p>⁶Strain provided by Sandra A. Larsen, Center for Disease Control and Prevention, Atlanta, GA.</p><p><i>T</i>. <i>pallidum</i> subsp. <i>pallidum</i> strains used in this study.</p

Reactivity of anti-TP0136 immune sera against recombinant TP0136 proteins and Inhibition of <i>T</i>. <i>pallidum</i> attachment to plasma and cellular fibronectin by anti-TP0136 immune sera.

<p>(A) Sera obtained from TP0136-H and TP0136-S-immunized rabbits recognized both recombinant full-length proteins and Frag. 1 and Frag. 2. Anti-TP0136-H antiserum recognized Frag.3-H but reacted only weakly against Frag.3-S. Similarly, anti-TP0136-S antiserum recognized Frag.3-S but reacted less well against Frag F3-H. Bars represent the absorbance at 405 nm ± SEM for triplicate samples. Significance between reactivity to single peptides was assessed by Student’s unpaired two-tailed t test with significance set at * <i>p<</i>0.05. (B) Antisera directed against TP0136-H and TP0136-S inhibited treponemal attachment to slides coated with plasma and cellular Fn. Experiments were repeated twice using each time triplicate wells per condition. Bars represent the mean number of <i>T</i>. <i>pallidum</i> cells counted in 10 fields of triplicate experiments (± standard error) following incubation of <i>T</i>. <i>pallidum</i> with either anti-TP0136 immune sera, IRS (positive control) or NRS (negative control). Significance is calculated with respect to NRS using the Student two-tailed t test with significance set at * <i>p<</i>0.05.</p

Primers used in this study.

<p>Primers used in this study.</p

TP0136 message quantification during experimental infection.

<p>For message quantification, a biopsy from the leading edge of a dermal lesion was obtained from each of the three infected rabbits every three days for 30 days. Each sample was amplified in triplicate. The data were reported as the mean values ± standard error (SE) for triplicate experiments. Left <i>y</i> axis shows real-time qPCR analysis of TP0136 message normalized to TP0547 mRNA (orange line) during progression of primary syphilitic lesions in the rabbit model. Although biopsies were obtained at day 0 and day 3 as well, no message quantification was possible from these samples. Newman-Keuls Multiple Comparison Test was used to assess significant differences in TP0136 message level between time points (*<i>p<</i>0.05) whenever a significant difference between sample means was found by ANOVA. Right <i>y</i> axis shows absolute quantification data for TP0574 message (black bars), reflecting absolute <i>T</i>. <i>pallidum</i> burden.</p

Human Papillomavirus Positivity in the Anal Canal in HIV-Infected and HIV-Uninfected Men Who Have Anal Sex with Men in Guangzhou, China: Implication for Anal Exams and Early Vaccination

Background. The epidemiology of HPV in men who have sex with men (MSM) in Guangzhou, China, had not been reported previously. Methods. HIV-infected and HIV-uninfected MSM were recruited from a Guangzhou-based MSM clinic in 2013. Sociodemographic characteristics and sexual behaviors were collected. An anal cytological sample was taken for HPV testing. Results. We recruited 79 HIV-infected and 85 HIV-uninfected MSM. The median age was 26 years in both groups. The positivities of anal HPV of any type (81.0% versus 48.2%), any high risk type (50.6% versus 27.1%), any low risk type (55.7% versus 31.8%), and any 9-valent vaccine type (74.7% versus 36.5%) were all significantly higher among HIV-infected compared to that among HIV-negative MSM (p for all < 0.05). The great majority of HPV-infected MSM were infected with 9-valent vaccine types (59 out of 64 HIV-infected and 31 out of 41 HIV-uninfected). Anal bacterial infections were associated with higher anal HPV positivity and greater number of anal HPV types. Conclusion. Sexually active MSM in Guangzhou, especially those infected with HIV, had high and multiple HPV detections. The majority of these cases were potentially preventable by HPV vaccine. Regular anal exams and early HPV vaccination are warranted in this population