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Biomedical subjects

J Kimata

Publications and source records attributed to J Kimata.

5 recordsLinked to original sources
PubMed2001

Identification of a simian immunodeficiency virus reverse transcriptase variant with enhanced replicational fidelity in the late stage of viral infection.

Genomic hypermutation of human and simian immunodeficiency viruses (HIV and SIV) enables these viruses to adapt and escape from various types of anti-viral selection by altering the molecular properties of viral gene products. In this study, we examined whether the biochemical and catalytic properties of SIV DNA polymerases (reverse transcriptases; RT) can change during the course of viral infection. For this test, we analyzed RTs obtained from two SIV clones, SIVMNE CL8 and SIVMNE 170. SIVMNE 170 was isolated during the late symptomatic phase of infection with the parental strain, SIVMNE CL8. We found these two RTs have identical DNA polymerase specific activities and kinetics with three different DNA and RNA templates. In addition, the processivity of these two SIV RT proteins were also similar. However, as demonstrated by a misincorporation assay, the SIVMNE 170 RT showed much higher fidelity than SIVMNE CL8. The fidelity difference between these two SIV RTs was also confirmed by a steady state kinetic fidelity assay. These findings suggest that the fidelity of lentiviral RTs may change during the course of viral infection, possibly in response to alterations of host anti-viral immune capability. In addition, our sequence analysis of these two RT genes proposes possible structural strategies that the virus may employ to alter RT fidelity.

Amino Acid Sequence↗
PubMed1989

Epidemiologic evidence for the development of serovar-specific immunity after gonococcal infection.

We tested the hypothesis that strain-specific immunity occurs after gonococcal infection in a longitudinal study of 227 prostitutes resident in one small community who experienced frequent gonococcal infections. Women were examined and cultured for Neisseria gonorrhoeae at 2-wk intervals. Gonococcal isolates were typed according to protein 1 serovar, auxotype, and beta-lactamase plasmid type, and classified as to serovar and strain. The hypothesis was tested by comparing the predictions of the hypothesis with the observations of the study. Over the 14-mo period of the study, major changes in the prevalence of specific serovars were observed in the gonococcal population infecting these women. Women with HIV infection experienced a higher rate of gonococcal infection (0.56 +/- 0.03 vs. 0.46 +/- 0.04, P less than 0.05, t test) compared with HIV-negative women and were more likely to experience multiple infections with the same strain. The duration of prostitution was inversely related to the frequency of gonococcal infection. Women experiencing an infection with a specific gonococcal serovar were at a 2- to 10-fold reduced risk of reinfection with the same serovar, except for the 1B-1 serovar. The results of the study were consistent with all four predictions of the hypothesis. Infection with a specific gonococcal serovar results in specific but incomplete protection against subsequent infection with the homologous serovar. The mechanism of this protection remains to be determined.

Adult↗
PubMedDate not supplied

Condom use prevents genital ulcers in women working as prostitutes. Influence of human immunodeficiency virus infection.

Control of genital ulcer disease (GUD) is a proposed intervention to slow the dissemination of human immunodeficiency virus (HIV) infection. Programs for the control of sexually transmitted diseases (STD) should focus on groups of high-frequency transmitters, such as prostitutes and their clientele. This study illustrates the interaction between the prevalence of chancroid, use of barrier prophylaxis against STDs, and HIV infection in a population of female prostitutes in Nairobi. Four hundred and twenty three women were evaluated. Despite the increased use of condoms, the prevalence of genital ulcers remained constant between 1986-87 and 1987-88. Genital ulcer disease was simultaneously associated with HIV infection (adjusted odds ratio: 3.7, P less than .01) whereas it was independently and inversely associated with more consistent condom use (P less than .01). The authors conclude that genital ulcer disease can be controlled in these populations but concurrent HIV infection increases the difficulty of this intervention.

Chancroid↗
PubMedDate not supplied

Efficacy of nonoxynol 9 contraceptive sponge use in preventing heterosexual acquisition of HIV in Nairobi prostitutes.

OBJECTIVE: To determine the efficacy of the nonoxynol 9 contraceptive sponge in preventing sexual acquisition of the human immunodeficiency virus (HIV). DESIGN: Prospective, randomized placebo-controlled trial. SETTING: Research clinic for prostitutes in Nairobi, Kenya. PATIENTS AND INTERVENTIONS: One hundred thirty-eight HIV-seronegative women were enrolled, of whom 74 were assigned to nonoxynol 9 sponge use and 64 to placebo use. These two groups did not significantly differ with respect to demographic characteristics, sexual practices, or prevalence of genital infections at enrollment, except for a lower number of sex partners per week and a higher initial prevalence of genital ulcers among women assigned to nonoxynol 9 sponge use. Among the 116 women who returned for follow-up, the mean durations of follow-up were 14 and 17 months for the two groups, respectively. MAIN OUTCOME MEASURE: HIV seroconversion. RESULTS: Nonoxynol 9 sponge use was associated with an increased frequency of genital ulcers (relative risk [RR], 3.3; P less than .0001) and vulvitis (RR, 3.3; P less than .0001) and a reduced risk of gonococcal cervicitis (RR, 0.4; P less than .0001). Twenty-seven (45%) of 60 women in the nonoxynol 9 sponge group and 20 (36%) of 56 women in the placebo group developed HIV antibodies. The hazard ratio for the association between nonoxynol 9 sponge use and HIV seroconversion was 1.7 (95% confidence interval [CI], 0.9 to 3.0). Using multivariate analysis to control for the presence of genital ulcers at enrollment, the adjusted hazard ratio for the association between nonoxynol 9 sponge use and seroconversion was 1.6 (95% CI, 0.8 to 2.8). CONCLUSIONS: Genital ulcers and vulvitis occurred with increased frequency in nonoxynol 9 sponge users. We were unable to demonstrate that nonoxynol 9 sponge use was effective in reducing the risk of HIV infection among highly exposed women.

Adult↗