Showing papers by "Myron S. Cohen published in 1999"

The effect of Plasmodium falciparum malaria on HIV-1 RNA blood plasma concentration

Abstract: Objectives: This study was undertaken to determine the relative effect of malaria infection on HIV concentration in blood plasma, and prospectively to monitor viral concentrations after antimalarial therapy. Design: A prospective, double cohort study was designed to compare the blood HIV-1 RNA concentrations of HIV-positive individuals with and without acute malaria illness. Subjects were followed for 4 weeks after successful malaria therapy, or for 4 weeks from enrollment (controls). Methods: Malawian adults with symptomatic Plasmodium falciparum parasitemia (malaria group) and asymptomatic, aparasitemic blood donors (control group) were tested for HIV-1 antibodies to identify appropriate study groups. The malaria group received antimalarial chemotherapy only and were followed with sequential blood films. In both groups, blood plasma HIV-1 RNA viral concentrations were determined at enrollment and again at 1, 2 and 4 weeks. Results: Forty-seven malaria patients and 42 blood donors were enrolled. At enrollment blood plasma HIV-1 RNA concentrations were approximately sevenfold higher in patients with malaria than in blood donors (medians 15.1 × 10 4 and 2.24 × 10 4 copies/ml, respectively, P = 0.0001). No significant changes in median HIV-1 concentrations occurred in the 21 blood donors followed to week 4 (P = 0.68). In the 27 subjects successfully treated for malaria who were followed to week 4, a reduction in plasma HIV-1 RNA was observed from a median of 19.1 × 10 4 RNA copies/ml at enrollment, to 12.0 × 10 4 copies/ml at week 4, (P = 0.02). Plasma HIV-1 concentrations remained higher in malaria patients than controls (median 12.0 × 10 4 compared with 4.17 × 10 4 copies/ml, P = 0.086). Conclusions: HIV-1 blood viral burden is higher in patients with P. falciparum malaria than in controls and this viral burden can, in some patients, be partly reduced with antimalarial therapy.

Sexual transmission of HIV: infectiousness and prevention.

Abstract: HIV can be transmitted through contaminated blood and blood products; from a mother to her offspring during pregnancy childbirth or breast feeding; or through sexual contact. Sexual transmission remains by far the predominant mode of transmission. Vertical and blood borne transmission of HIV are highly predictable and very efficient modes. The recipient of a unit of contaminated blood nearly always becomes infected whereas only about 0.3% of people pierced with large bore needles seroconvert. This difference in efficiency most probably reflects the dissimilar concentrations of viruses inoculated. Vertical transmission leads to infection in about 25% of newborns. Sexual transmission of HIV however appears to be considerably less efficient and highly variable. To develop effective prevention strategies a better understanding of the factors affecting transmission of HIV is required. (excerpt)

Characterization of V3 Sequence Heterogeneity in Subtype C Human Immunodeficiency Virus Type 1 Isolates from Malawi: Underrepresentation of X4 Variants

Abstract: We have examined the nature of V3 sequence variability among subtype C human immunodeficiency virus type 1 (HIV-1) sequences from plasma-derived viral RNA present in infected men from Malawi. Sequence variability was assessed by direct sequence analysis of the V3 reverse transcription-PCR products, examination of virus populations by a subtype C V3-specific heteroduplex tracking assay (V3-HTA), and selected sequence analysis of molecular clones derived from the PCR products. Sequence variability in V3 among the subtype C viruses was not associated with the presence of basic amino acid substitutions. This observation is in contrast to that for subtype B HIV-1, where sequence variability is associated with such substitutions, and these substitutions are determinants of altered coreceptor usage. Evolutionary variants in subtype C V3 sequences, as defined by the V3-HTA, were not correlated with the CD4 level in the infected person, while such a correlation was found with subtype B V3 sequences. Viruses were isolated from a subset of the subjects; all isolates used CCR5 and not CXCR4 as a coreceptor, and none was able to grow in MT-2 cells, a hallmark of the syncytium-inducing phenotype that is correlated with CXCR4 usage. The overall sequence variability of the subtype C V3 region was no greater than that of the conserved regions of gp120. This limited sequence variability was also a feature of subtype B V3 sequences that do not carry the basic amino acid substitutions associated with altered coreceptor usage. Our results indicate that altered coreceptor usage is rare in subtype C HIV-1 isolates in sub-Saharan Africa and that sequence variability is not a feature of the V3 region of env in the absence of altered coreceptor usage.

Trichomonas vaginalis as a cause of urethritis in Malawian men.

Abstract: This study was conducted to determine the prevalence of trichomoniasis in Malawian men to evaluate a polymerase chain reaction (PCR) detection assay for T. vaginalis in urethral swab samples and to examine the effect of T. vaginalis infection on HIV excretion in the semen. There were 206 men with symptomatic urethritis in STD clinic and 127 asymptomatic men in the Dermatology Clinic who were enrolled from January to March 1996. Results according to a wet-mount microscopy and urethral swabs culture combination showed that of 293 men only 38 (13%) men were positive for T. vaginalis. The estimated prevalence among symptomatic and asymptomatic cases was 15.7% and 8.7% respectively. The PCR yielded a sensitivity of 0.82 (95% CI: 0.66-0.92) and specificity of 0.95 (95% CI: 0.91-0.97); these were compared to the wet-mount microscopy and culture combination. Overall HIV seroprevalence of men was 51% because gonococcal urethritis was shown to significantly increase seminal HIV RNA levels. The median HIV RNA concentration in seminal plasma from men with symptomatic urethritis plus T. vaginalis infection was significantly higher than in seminal plasma from HIV-positive men with symptomatic urethritis only. Since this study has several important limitations a randomized clinical trial would be useful for determining whether urethritis cure rates can be significantly improved.

Human experimentation with Neisseria gonorrhoeae: progress and goals.

Abstract: Infection with Neisseria gonorrhoeae has adverse consequences for reproductive health and facilitates the transmission of the human immunodeficiency virus. A major limitation in the development of gonococcal vaccines has been the lack of an animal model. Urethral infection can be initiated in male volunteer subjects through urethral inoculation. Several hundred patients have participated in studies using this experimental infection model. These studies have helped define the natural history of experimental infection and provided a better understanding of phenotypic and genotypic variation of gonococci in vivo. Isogenic molecular mutants can be used to define a role for gonococcal surface structures, including pilin and transferrin-binding proteins; recent results demonstrate that gonococci unable to express transferrin- and lactoferrin-binding proteins cannot cause urethral infection. The experimental model has proven to be an efficient means of studying gonococcal infection and focusing vaccine development. In addition, this model should allow vaccines to be tested quickly and efficiently.

Chancroid, primary syphilis, genital herpes, and lymphogranuloma venereum in Antananarivo, Madagascar

Abstract: Ulcer material from consecutive patients attending clinics in Antananarivo, Madagascar, was tested using multiplex polymerase chain reaction (M-PCR) to detect Treponema pallidum, Haemophilus ducreyi, and herpes simplex virus. Sera were tested for syphilis and for IgG and IgM antibodies to Chlamydia trachomatis by microimmunofluorescence testing (MIF). By M-PCR, 33% of 196 patients had chancroid, 29% had syphilitic ulcers, and 10% had genital herpes; 32% of the ulcer specimens were M-PCR negative. Compared with M-PCR, syphilis serology was 72% sensitive and 83% specific. The sensitivity of clinical diagnosis of syphilis, chancroid, and genital herpes was 93%, 53%, and 0% and specificity was 20%, 52%, and 99%, respectively. Less schooling was associated with increased prevalence of syphilitic ulcers (P=.001). Sixteen patients (8%) were clinically diagnosed with lymphogranuloma venereum (LGV); 1 plausible case of LGV was found by MIF. In Madagascar, primary care of genital ulcers should include syndromic treatment for syphilis and chancroid.

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

Abstract: 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.

Nucleoside Analogues Achieve High Concentrations in Seminal Plasma: Relationship between Drug Concentration and Virus Burden

Abstract: Human immunodeficiency virus (HIV) can be transmitted in semen from a man to his sexual partners Antiretroviral drugs are likely to affect the amount of HIV-1 in semen and perhaps transmission of the virus The concentrations of zidovudine, lamivudine, and HIV-1 RNA in blood and seminal plasma were measured in 9 HIV-positive men over

Longitudinal Evaluation of Serovar-specific Immunity to Neisseria gonorrhoeae

Abstract: 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.

Genital Ulcers: Etiology, Clinical Diagnosis, and Associated Human Immunodeficiency Virus Infection in Kingston, Jamaica

Abstract: Individuals presenting consecutively with genital ulcers in Kingston, Jamaica, underwent serological testing for human immunodeficiency virus (HIV) infection, chlamydial infection, and syphilis. Ulcer material was analyzed by multiplex polymerase chain reaction (M-PCR) analysis. DNA from herpes simplex virus (HSV), Haemophilus ducreyi, and Treponema pallidum was detected in 158 (52.0%), 72 (23.7%), and 31 (10.2%) of 304 ulcer specimens. Of the 304 subjects, 67 (22%) were HIV-seropositive and 64 (21%) were T. pallidum-seroreactive. Granuloma inguinale was clinically diagnosed in nine (13.4%) of 67 ulcers negative by M-PCR analysis and in 12 (5.1%) of 237 ulcers positive by M-PCR analysis (P = .03). Lymphogranuloma venereum was clinically diagnosed in eight patients. Compared with M-PCR analysis, the sensitivity and specificity of a clinical diagnosis of syphilis, herpes, and chancroid were 67.7%, 53.8%, and 75% and 91.2%, 83.6%, and 75.4%, respectively. Reactive syphilis serology was 74% sensitive and 85% specific compared with M-PCR analysis. Reported contact with a prostitute in the preceding 3 months was associated with chancroid (P = .009), reactive syphilis serology (P = .011), and HIV infection (P = .007). The relatively poor accuracy of clinical and locally available laboratory diagnoses pleads for syndromic management of genital ulcers in Jamaica. Prevention efforts should be intensified.

A Neisseria gonorrhoeae immunoglobulin A1 protease mutant is infectious in the human challenge model of urethral infection.

Abstract: Many mucosal pathogens, including Neisseria gonorrhoeae, produce proteases that cleave immunoglobulin A (IgA), the predominant immunoglobulin class produced at mucosal surfaces. While considerable circumstantial evidence suggests that IgA1 protease contributes to gonococcal virulence, there is no direct evidence that N. gonorrhoeae requires IgA1 protease activity to infect a human host. We constructed a N. gonorrhoeae iga mutant without introducing new antibiotic resistance markers into the final mutant strain and used human experimental infection to test the ability of the mutant to colonize the male urethra and to cause gonococcal urethritis. Four of the five male volunteers inoculated with the Iga− mutant became infected. In every respect—clinical signs and symptoms, incubation period between inoculation and infection, and the proportion of volunteers infected—the outcome of human experimental infection with FA1090iga was indistinguishable from that previously reported for a variant of parent strain FA1090 matching the mutant in expression of Opa proteins, lipooligosaccharide, and pilin. These results indicate that N. gonorrhoeae does not require IgA1 protease production to cause experimental urethritis in males.

An epidemiological evaluation of the use of microbiological tools for identifying gonorrhoea infection networks.

Abstract: We aimed to assess the utility of various techniques for identifying gonorrhoea infection networks. All residents of a non-metropolitan North Carolina county visiting a sexually transmitted disease (STD) clinic during a 17-month period were screened for gonorrhoea. Infection networks were estimated by serovar type combined with antibiotic resistance, arbitrarily primed polymerase chain reaction (AP-PCR), or temporal clustering. The residential addresses of infected patients were geocoded and mapped. Among 2 serovar types, the presence of distinguishing characteristics of a network, based on questionnaire data, was assessed with prevalence ratios and 95% confidence intervals (CIs) relative to those not in the network. Twenty-five serovar types were identified among 759 gonorrhoea infections. In one serovar, the networks further delineated by temporal clusters correlated with particular AP-PCR types. In most instances, however, different typing techniques painted different network pictures. No refined serovar network stood out as having a particular set of characteristics that could be used to shape intervention. Teasing out an individual infection network with unique characteristics will require the development and use of other microbiological tools.

14n-spin trapping of free radicals in the presence of 15n-spin labeled neisseria gonorrhoeae

Abstract: One of the difficult tasks confronting the study of free radicals in biology is the inability to measure “on line” injury to a biological target, while characterizing the reactive species responsible for the toxic event. This is particularly relevant in light of the fact that specific free radicals play a critical role in host immune response. An approach towards addressing this important issue draws upon the unique EPR spectral properties of 14N/15N-labeled compounds. In particular, Neisseria gonorrhoeae has been covalently labeled with 15N-deuterium17-containing 4-maleimido-2,2,6,6-tetramethylpiperidin-1-yloxyl (15N-D17-4-MAL-TEMPO). The EPR spectrum from bacteria so labeled exhibited two low-field peaks: (a) a broad, strongly immobilized species classified as “S”; (b) a more narrow, weakly immobilized component termed “W”. The W/S ratio is an indicator of changes in membrane organization. In the presence of the superoxide-generating system, hypoxanthine/xanthine oxidase, an increase in the W/S ratio from 3.3 for control to 6.4 was observed, which was only partially inhibited by superoxide dismutase (W/S ratio of 4.4). When the spin trap 5,5-dimethyl-1-pyrroline 14N-oxide (DMPO) was included in the above reaction mixture, an EPR spectrum was recorded, which was a composite of 2,2,-dimethyl-5-hydroperoxypyrrolidin-1-yl-14N-oxyl (DMPO-OOH) and 15N-D17-4-MAL-TEMPO-labeled Neisseria gonorrhoeae. With the use of computer subtraction procedures, the W/S ratio was found to be 6.4. The experiments demonstrate the utility of 14N/15N-labeled aminoxyls as a valuable tool in accessing the effects of specific free radicals on the fluidity of cell membranes.

Collection and Processing of Seminal Plasma for the Quantitation of HIV-1 RNA by NASBA and RT-PCR

Abstract: Semen is the major vehicle for the sexual transmission of HIV-1. The ability to isolate infectious HIV from the semen and to quantitate viral burden in the form of cell-free or cell-associated HIV-1 RNA in semen are important for epidemiologic and public health aspects of the epidemic. Earlier studies used viral culture to detect HIV in semen. Cell associated culturable virus recovery rates ranged from 8 to 55% (1-8). Much lower recovery rates (3-15%) were reported by these investigators for cell-free seminal plasma. In general, subjects with lower CD4 counts, higher seminal plasma viral load (>3.5-4 log(10)), and an AIDS diagnosis were more apt to have positive seminal cell HIV cultures.