Factors associated with HIV infection in married or cohabitating couples in Kenya: results from a nationally representative study

Background

In order to inform prevention programming, we analyzed HIV discordance and concordance within couples in the Kenya AIDS Indicator Survey (KAIS) 2007.

Methods

KAIS was a nationally representative population-based sero-survey that examined demographic and behavioral indicators and serologic testing for HIV, HSV-2, syphilis, and CD4 cell counts in 15,853 consenting adults aged 15–64 years. We analyzed interview and blood testing data at the sexual partnership level from married or cohabitating couples. Multivariable regression models were used to identify factors independently associated with HIV discordant and concordant status.

Results

Of 3256 couples identified in the survey, 2748 (84.4%) had interview and blood testing data. Overall, 3.8% of couples were concordantly infected with HIV, and in 5.8% one partner was infected, translating to 338,000 discordant couples in Kenya. In 83.6% of HIV-infected Kenyans living in married or cohabitating couples neither partner knew their HIV status. Factors independently associated with HIV-discordance included young age in women (AOR 1.5, 95% CI: 1.2–1.8; p<0.0001), increasing number of lifetime sexual partners in women (AOR 1.5, 95% CI: 1.3–1.8; p<0.0001), HSV-2 infection in either or both partners (AOR 4.1, 95% CI: 2.3–7.2; p<0.0001), and lack of male circumcision (AOR 1.6, 95% CI: 1.0–2.5; p = 0.032). Independent factors for HIV-concordance included HSV-2 infection in both partners (AOR 6.5, 95% CI: 2.3–18.7; p = 0.001) and lack of male circumcision (AOR 1.8, 95% CI: 1.0–3.3; p = 0.043).

Conclusions

Couple prevention interventions should begin early in relationships and include mutual knowledge of HIV status, reduction of outside sexual partners, and promotion of male circumcision among HIV-uninfected men. Mechanisms for effective prevention or suppression of HSV-2 infection are also needed.     

The extraction and analysis of lipopolysaccharides from Pseudomonas aeruginosa strain PAO, and three rough mutants.

Three spontaneously arising rough mutants of Pseudomonas aeruginosa have been isolated by selection for resistance to virulent lipopolysaccharide (LPS) specific bacteriophages. In addition, the first phages specific for rough mutants of P. aeruginosa were isolated. Using these phage and autoagglutination patterns in 4% NaCl and acriflavine, these mutants could be clearly distinguished from the wild-type strain and each other. Chemical analysis of the LPS together with chromatographic resolution of the polysaccharide moieties showed alterations in both O-specific side chains and core regions.     

Modulation of Calmodulin mRNA and Protein Levels in Barley Aleurone

Changes in calmodulin (CaM) mRNA and protein were investigated in aleurone layers of barley (Hordeum vulgare L. cv Himalaya) incubated in the presence and absence of calcium, gibberellic acid (GA3), and abscisic acid (ABA). CaM mRNA levels increased rapidly and transiently following incubation of aleurone layers in H2O, CaCl2, or GA3. The increase in CaM mRNA was prevented by ABA. This increase in CaM mRNA was brought about by physical stimulation during removal of the starchy endosperm from the aleurone layer. CaM protein levels did not increase in response to physical stimulation. Only incubation in GA3 plus CaCl2 brought about a rapid increase in CaM protein levels in the aleurone cell. ABA reduced the level of CaM protein below that found at the beginning of the incubation period. The rise in CaM protein preceded increases in the synthesis and secretion of [alpha]-amylase. Immunocytochemistry with monoclonal antibodies to carrot and mung bean CaM was used to localize CaM in aleurone protoplasts. Monoclonal antibodies to tubulin and polyclonal antibodies to tonoplast intrinsic protein and malate synthase were used as controls. CaM was localized to the nucleus, the vacuolar membrane, and the cytosol, but was not associated with microtubules.     

Variable clinical responses of a scrub typhus outbred mouse model to feeding by Orientia tsutsugamushi infected mites

Rodents are the natural hosts for Leptotrombidium mites that transmit Orientia tsutsugamushi, the causative agent of scrub typhus, a potentially fatal febrile human disease. Utilizing mite lines that included O. tsutsugamushi infected and non-infected Leptotrombidium species we investigated the varied infection response of outbred mice (ICR) exposed to L. chiangraiensis (Lc), L. imphalum (Li) and L. deliense (Ld). Each of six mite lines (Lc1, Lc5, Li3, Li4, Li7 and Ld) was separately placed in the inner ears of ICR mice either as a single individual (individual feeding, IF) or as a group of 2-4 individuals (pool feeding, PF). The species of infected chigger feeding on mice significantly affected mortality rates of the mice, with mite lines of Lc causing higher mean (±SE) mortality (90.7 ± 3.6 %) than mite lines of Li (62.9 ± 5.6 %) or Ld (53.6 ± 5.8 %). Mouse responses which included time to death, food consumption and total mice weight change depended on mite species and their O. tsutsugamushi genotype, more than on feeding procedure (IF vs. PF) except for mite lines within the Lc. Infected mite lines of Lc were the most virulent infected mites assessed whereas the infected Ld species was the least virulent for the ICR. Mice killed by various mite lines showed enlarged spleens and produced ascites. The results of this investigation of the clinical responses of ICR mice to feeding by various infected mite lines indicated that the different species of infected mites and their O. tsutsugamushi genotype produced different clinical presentations in ICR mice, a scrub typhus mouse model which mimics the natural transmission of O. tsutsugamushi that is critical for understanding scrub typhus disease in terms of natural transmission, host-pathogen-vector interaction and vaccine development.     

Nitrogen enrichment contributes to positive responses to soil microbial communities in three invasive plant species

Increased resource availability and feedbacks with soil biota have both been invoked as potential mechanisms of plant invasion. Nitrogen (N) deposition can enhance invasion in some ecosystems, and this could be the result of increased soil N availability as well as shifts in soil biota. In a two-phase, full-factorial greenhouse experiment, we tested effects of N availability and N-impacted soil communities on growth responses of three Mediterranean plant species invasive in California: Bromus diandrus, Centaurea melitensis, and Hirschfeldia incana. In the first phase, plants were grown individually in pots and inoculated with sterile soil, soil from control field plots or soil from high N addition plots, and with or without supplemental N. In the second phase, we grew the same species in soils conditioned in the first phase. We hypothesized growth responses would differ across species due to species-specific relationships with soil biota, but overall increased N availability and N-impacted soil communities would enhance plant growth. In the first phase, Centaurea had the greatest growth response when inoculated with N-impacted soil, while Bromus and Hirschfeldia performed best in low N soil communities. However, in phase two all species exhibited positive growth responses in N-impacted soil communities under high N availability. While species may differ in responses to soil biota and N, growth responses to soils conditioned by conspecifics appear to be most positive in all species under high N availability and/or in soil communities previously impacted by simulated N deposition. Our results suggest N deposition could facilitate invasion due to direct impacts of soil N enrichment on plant growth, as well as through feedbacks with the soil microbial community.     

Microglial phagocytosis of apoptotic inflammatory T cells leads to down-regulation of microglial immune activation.

Apoptotic cell death is an established mechanism to terminate an inflammatory response in rodent or human brains. Microglia, as the resident phagocyte, is a strong candidate for the clearance of apoptotic lymphocytes. Apoptosis was induced in cultured autologous thymocytes and in myelin basic protein (MBP)-specific, encephalitogenic T cells from Lewis rats by the addition of 0.1 microg/ml methylprednisolone. The amount of phagocytosis of apoptotic cells was assessed using an in vitro phagocytosis assay. Supernatants were collected to measure microglial cytokine secretion. The state of immune activation in microglia was investigated by a T cell proliferation assay and by flow cytometric analysis of microglial surface expression of immune molecules. Microglia ingested specifically apoptotic cells (apoptotic thymocytes as well as MBP-specific T cells) in contrast to nonapoptotic control cells (p < 0.0001). Subsequent secretion of the proinflammatory cytokines TNF-alpha and IL-12 was significantly decreased, while the secretion of IL-10 and TGF-beta was not affected. Furthermore, ingestion of apoptotic cells led to increased microglial MHC class II expression without concomitant increase in MHC class I, costimulatory molecules, and ICAM expression. The Ag-specific activation of MBP-specific T cells in cocultures with microglia that had ingested apoptotic cells was significantly less than that of identical T cells that interacted with nonphagocytosing microglia. Together with negative results obtained in a trans-well system, this is in support of a cell contact-mediated effect. Microglia might play an important role in the clearance of apoptotic cells. The uptake of apoptotic cells by microglia is tolerogenic and results in a reduced proinflammatory cytokine production and a reduced activation of encephalitogenic T cells. This might help to restrict an autoimmune inflammation and minimize damage in the inflamed brain.