https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(97)02190-9.pdf

Reduction of concentration of HIV-1 in semen after treatment of urethritis: implications for prevention of sexual transmission of HIV-1

The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100 ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as "one of the most wonderful in the world". The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of action potentials in the leaves. Here we complement these studies by considering the post-stimulation mechanical aspects of Venus flytrap closure. Using high-speed video imaging, non-invasive microscopy techniques and a simple theoretical model, we show that the fast closure of the trap results from a snap-buckling instability, the onset of which is controlled actively by the plant. Our study identifies an ingenious solution to scaling up movements in non-muscular engines and provides a general framework for understanding nastic motion in plants.

How the Venus flytrap snaps

In large metropolitan areas, which typically have the highest rates of gonorrhea, the identification of chains of transmission by use of partner notification is problematic, and there is an increasing interest in applying molecular approaches, which would require new discriminatory high-throughput procedures for recognizing clusters of indistinguishable gonococci, procedures that identify local chains of transmission. Sequencing of internal fragments of 2 highly polymorphic loci, from 436 isolates recovered in London during a 3-month period, identified clusters of antibiotic-resistant and antibiotic-susceptible isolates with indistinguishable genotypes, the vast majority of which were also identical or closely related by other methods, and defined groups of individuals who typically had similar demographic characteristics. This discriminatory sequence-based approach produces unambiguous data that easily can be compared via the Internet and appears to be suitable for the identification of linked cases of gonorrhea and the timely identification of transmission of antibiotic-resistant strains, even within large cities.

Rapid Sequence-Based Identification of Gonococcal Transmission Clusters in a Large Metropolitan Area

Infection with Neisseria gonorrhoeae can trigger an intense inflammatory response, yet there is little specific immune response or development of immune memory. In addition, gonorrhea typically correlates with a transient reduction in T lymphocyte counts in blood, and these populations recover when gonococcal infection is resolved. Such observations suggest that the gonococci have a suppressive effect on the host immune response. We report here that N. gonorrhoeae Opa proteins were able to bind CEACAM1 expressed by primary CD4+ T lymphocytes and suppress their activation and proliferation. CEACAM1 bound by gonococcal Opa52 associated with the tyrosine phosphatases SHP-1 and SHP-2, which implicates the receptor's ITIM (immunoreceptor tyrosine-based inhibitory motif) in this effect.

/pdf/neisserial-binding-to-ceacam1-arrests-the-activation-and-49yfleblly.pdf

Neisserial binding to CEACAM1 arrests the activation and proliferation of CD4 + T lymphocytes

Determining the magnitude of chlamydia and gonorrhea reinfection is critical to inform evidence-based clinical practice guidelines related to retesting after treatment. PubMed was used to identify peer-reviewed English language studies published in the past 30 years that estimated reinfection rates among females treated for chlamydia or gonorrhea. Included in this analysis were original studies conducted in the United States and other industrialized countries that reported data on chlamydia or gonorrhea reinfection in females. Studies were stratified into 3 tiers based on study design. Reinfection rates were examined in relation to the organism, study design, length of follow-up, and population characteristics. Of the 47 studies included, 16 were active cohort (Tier 1), 15 passive cohort (Tier 2), and 16 disease registry (Tier 3) studies. The overall median proportion of females reinfected with chlamydia was 13.9% (n = 38 studies). Modeled chlamydia reinfection within 12 months demonstrated peak rates of 19% to 20% at 8 to 10 months. The overall median proportion of females reinfected with gonorrhea was 11.7% (n = 17 studies). Younger age was associated with higher rates of both chlamydia and gonorrhea reinfection. High rates of reinfection with chlamydia and gonorrhea among females, along with practical considerations, warrant retesting 3 to 6 months after treatment of the initial infection. Further research should investigate effective interventions to reduce reinfection and to increase retesting.

Repeat Infection With Chlamydia and Gonorrhea Among Females: A Systematic Review of the Literature

Thirty-three Neisseria gonorrhoeae isolates from 15 persons infected multiple times with the same serovar were compared using por gene sequencing, opa-typing, and arbitrarily primed-polymerase chain reaction. All three molecular techniques were more discriminatory than serotyping and identified differences between some isolates belonging to the same serovar. Although there were differences among Por sequences within some serovars, 10 of 15 subjects became reinfected with gonococci expressing identical Por proteins. Sequence analysis of por genes revealed evidence of horizontal genetic exchange and point mutations in potential surface-exposed regions during passage in the community.

https://www.jstor.org/stable/info/30117277

Molecular Typing of Neisseria gonorrhoeae Causing Repeated Infections: Evolution of Porin during Passage within a Community

The serovars of Neisseria gonorrhoeae that are predominant in a community change over time, a phenomenon that may be due to the development of immunity to repeat infection with the same serovar. This study evaluated the epidemiologic evidence for serovar-specific immunity to N. gonorrhoeae. During a 17-month period in 1992-1994, all clients of a sexually transmitted disease clinic in rural North Carolina underwent genital culture for N. gonorrhoeae. Gonococcal isolates were serotyped according to standard methods. Odds ratios for repeat infection with the same serovar versus any different serovar were calculated on the basis of the distribution of serovars in the community at the time of reinfection. Of 2,838 patients, 608 (21.4%; 427 males and 181 females) were found to be infected with N. gonorrhoeae at the initial visit. Ninety patients (14.8% of the 608) had a total of 112 repeat gonococcal infections. Repeat infection with the same serovar occurred slightly more often than would be expected based on the serovars prevalent in the community at the time of reinfection, though the result was marginally nonsignificant (odds ratio = 1.5, 95% confidence interval 1.0-2.4; p = 0.05). Choosing partners within a sexual network may increase the likelihood of repeat exposure to the same serovar of N. gonorrhoeae. Gonococcal infection did not induce evident immunity to reinfection with the same serovar.

/pdf/longitudinal-evaluation-of-serovar-specific-immunity-to-wutolxclj3.pdf

Longitudinal Evaluation of Serovar-specific Immunity to Neisseria gonorrhoeae

OBJECTIVE: To determine the number of Neisseria gonorrhoeae organisms in urine and semen in men with gonococcal urethritis, and to compare selected phenotypic characteristics of organisms harvested from the urethra and semen. DESIGN: Samples from two groups of subjects were examined. Patients with symptomatic urethritis receiving treatment at an STD clinic, as well as six subjects with experimental urethritis. Semen and urine specimens were obtained after the urethral exudate was sampled. RESULTS: Using quantitative cultures, we found an average of 6 x 10(6) gonococci in urine or semen of 17 men with symptomatic urethritis seeking treatment at an STD clinic, and 2 x 10(4) gonococci in secretions of six male subjects with early experimental infection. Gonococcal outer membrane opacity (Opa) proteins and lipo-oligosaccharide (LOS) recovered from urine and semen of these subjects were very similar. CONCLUSIONS: Men with symptomatic gonorrhoea excrete a large number of gonococci in semen which is not affected by the duration of symptoms. The similar phenotype of organisms in urine and semen suggests the bacteria come from the same compartment. These data help to explain the efficiency of gonococcal transmission from men to their partners, and identify an appropriate target for a preventative vaccine or immunotherapy designed to reduce the inoculum in infected patients.

https://sti.bmj.com/content/sextrans/73/5/378.full.pdf

Characterisation of Neisseria gonorrhoeae in semen during urethral infection in men.

Background and Objectives: The spread of sexually transmitted diseases (STDs), including gonorrhea, is affected by the duration of infection. Oral antibiotic therapy for gonococcal infection has been shown to be as effective as conventional intramuscular injection with ceftriaxone. Rapid cure would be expected to limit further spread of gonorrhea. However, the speed with which Neisseria gonorrhoeae is eliminated from the urogenital tract has not been evaluated. Goal of this Study: To determine the time required for elimination of Neisseria gonorrhoeae from the urine, mucosa, and semen in male subjects after treatment with ceftriaxone (250 mg intramuscularly), ciprofloxacin (500 mg by mouth, single dose) or cefixime (400 mg by mouth, single dose). Results: In 14 subjects, gonococci were eliminated from the urine within 4 hours of therapy and the mucosa within 24 hours after therapy. In 9 additional subjects, gonococci were eliminated from the semen by 24 hours after therapy. Conclusion: These results support the efficacy of single-dose oral therapy for gonorrhea and suggest that earlier follow-up for proof of cure in clinical trials of new antibiotics for gonorrhea may be acceptable. Rapid elimination of gonorrhea reduces the risk for continued transmission of the organism

Time required for elimination of Neisseria gonorrhoeae from the urogenital tract in men with symptomatic urethritis: comparison of oral and intramuscular single-dose therapy.

Rachael H. Davis

Papers

Molecular Typing of Neisseria gonorrhoeae Causing Repeated Infections: Evolution of Porin during Passage within a Community

Longitudinal Evaluation of Serovar-specific Immunity to Neisseria gonorrhoeae

Characterisation of Neisseria gonorrhoeae in semen during urethral infection in men.

Time required for elimination of Neisseria gonorrhoeae from the urogenital tract in men with symptomatic urethritis: comparison of oral and intramuscular single-dose therapy.

Characterisation ofNeisseria gonorrhoeae insemen during urethral infection inmen