Can High Density, Short Duration Grazing Replace Fire in a South African Mesic Grassland?

High density grazing (HDG), defined as the concentration of many livestock on a small area for a short period of time has become increasingly popular in the South African mesic grassland yet little is known about it impact. HDG is usually applied without fire, based on the assertion that it is a key contributor to desertification of grasslands. However, fire plays an important role in the development and growth of most South African mesic grassland plant species, as it stimulates resprouting and reduces competition for light. The aim of this study was to determine the impacts of high density grazing on plant species composition and soil physical properties in a South African mesic grassland. Using a fence-line contrast, the objectives were to compare the impact of HDG with annually burnt firebreaks; one which was grazed and the other one which was not grazed, on soil compaction, ground cover and species composition. Soils under HDG and annual burning with grazing were 54% and 32% more compacted, respectively compared to annual burning with no grazing. High density grazing compared to annual burning irrespective of grazing resulted in four-fold more litter accumulation that can reduce irradiation received by plants and limit growth. Grass species diversity was 10% lower under HDG and annual burning with grazing compared to annual burning with no grazing. Forb species diversity was similar between HDG and annual burning with no grazing. However, Jaccard’s dissimilarity index, showed a forb species turnover of 22%, with HDG having 3 and annual burn with no grazing having 2 unique species, indicating that fire dependent species may have been replaced with fire independent species under HDG. Findings from this study indicate that HDG cannot replace the role of fire and potentially has a negative impact on a South African mesic grassland

Factors Associated With Sexual Coercion in a Representative Sample of Men in Australian Prisons

Very little research has focused on men or prisoners as victims of sexual violence. This study provides the first population-based analysis of factors associated with sexual coercion of men in Australian prisons, and the first to use a computer-assisted telephone interview to collect this information in a prison setting. A random sample of men in New South Wales and Queensland prisons were surveyed using computer-assisted telephone interviewing. We asked participants about sexual coercion, defined as being forced or frightened into doing something sexually that was unwanted while in prison. Associations between sexual coercion in prison and sociodemographics, sexual coercion history outside of prison, and prison-related factors were examined. Logistic regression was used to estimate adjusted odds ratios in examining factors associated with sexual coercion in prisons. Of 2626 eligible men, 2000 participated. Participants identifying as non-heterosexual and those with a history of sexual coercion outside prison were found to be most at risk. Those in prison for the first time and those who had spent more than 5 years in prison ever were also more likely to report sexual coercion. Although prison policies and improving prison officer training may help address immediate safety and health concerns of those at risk, given the sensitivity of the issue and likely under-reporting to correctional staff, community-based organizations and prisoner peer-based groups arguably have a role too in providing both preventive and trauma-focused support

Short communication: CD8(+) T cell polyfunctionality profiles in progressive and nonprogressive pediatric HIV type 1 infection.

Pediatric HIV-1 infection is characterized by rapid disease progression and without antiretroviral therapy (ART), more than 50% of infected children die by the age of 2 years. However, a small subset of infected children progresses slowly to disease in the absence of ART. This study aimed to identify functional characteristics of HIV-1-specific T cell responses that distinguish children with rapid and slow disease progression. Fifteen perinatally HIV-infected children (eight rapid and seven slow progressors) were longitudinally studied to monitor T cell polyfunctionality. HIV-1-specific interferon (IFN)-γ(+) CD8(+) T cell responses gradually increased over time but did not differ between slow and rapid progressors. However, polyfunctional HIV-1-specific CD8(+) T cell responses, as assessed by the expression of four functions (IFN-γ, CD107a, TNF-α, MIP-1β), were higher in slow compared to rapid progressors (p=0.05) early in infection, and was associated with slower subsequent disease progression. These data suggest that the quality of the HIV-specific CD8(+) T cell response is associated with the control of disease in children as has been shown in adult infection

Influence of Gag-Protease-Mediated Replication Capacity on Disease Progression in Individuals Recently Infected with HIV-1 Subtype C

HLA class I-mediated selection of immune escape mutations in functionally important Gag epitopes may partly explain slower disease progression in HIV-1-infected individuals with protective HLA alleles. To investigate the impact of Gag function on disease progression, the replication capacities of viruses encoding Gag-protease from 60 individuals in early HIV-1 subtype C infection were assayed in an HIV-1-inducible green fluorescent protein reporter cell line and were correlated with subsequent disease progression. Replication capacities did not correlate with viral load set points (P = 0.37) but were significantly lower in individuals with below-median viral load set points (P = 0.03), and there was a trend of correlation between lower replication capacities and lower rates of CD4 decline (P = 0.09). Overall, the proportion of host HLA-specific Gag polymorphisms in or adjacent to epitopes was negatively associated with replication capacities (P = 0.04), but host HLA-B-specific polymorphisms were associated with higher viral load set points (P = 0.01). Further, polymorphisms associated with host-specific protective HLA alleles were linked with higher viral load set points (P = 0.03). These data suggest that transmission or early HLA-driven selection of Gag polymorphisms results in reduced early cytotoxic T-lymphocyte (CTL) responses and higher viral load set points. In support of the former, 46% of individuals with nonprotective alleles harbored a Gag polymorphism exclusively associated with a protective HLA allele, indicating a high rate of their transmission in sub-Saharan Africa. Overall, HIV disease progression is likely to be affected by the ability to mount effective Gag CTL responses as well as the replication capacity of the transmitted virus

Impact of select immunologic and virologic biomarkers on CD4 cell count decrease in patients with chronic HIV-1 subtype C infection: results from Sinikithemba Cohort, Durban, South Africa.

BACKGROUND: The extent to which immunologic and clinical biomarkers influence human immunodeficiency virus type 1 (HIV-1) infection outcomes remains incompletely characterized, particularly for non-B subtypes. On the basis of data supporting in vitro HIV-1 protein-specific CD8 T lymphocyte responses as correlates of immune control in cross-sectional studies, we assessed the relationship of these responses, along with established HIV-1 biomarkers, with rates of CD4 cell count decrease in individuals infected with HIV-1 subtype C. METHODS: Bivariate and multivariate mixed-effects models were used to assess the relationship of baseline CD4 cell count, plasma viral load, human leukocyte antigen (HLA) class I alleles, and HIV-1 protein-specific CD8 T cell responses with the rate of CD4 cell count decrease in a longitudinal population-based cohort of 300 therapy-naive, chronically infected adults with baseline CD4 cell counts >200 cells/mm(3) and plasma viral loads >500 copies/mL over a median of 25 months of follow-up. RESULTS: In bivariate analyses, baseline CD4 cell count, plasma viral load, and possession of a protective HLA allele correlated significantly with the rate of CD4 cell count decrease. No relationship was observed between HIV-1 protein-specific CD8 T cell responses and CD4 cell count decrease. Results from multivariate models incorporating baseline CD4 cell counts (201-350 vs >350 cells/mm(3)), plasma viral load (< or =100,000 vs >100,000 copies/mL), and HLA (protective vs not protective) yielded the ability to discriminate CD4 cell count decreases over a 10-fold range. The fastest decrease was observed among individuals with CD4 cell counts >350 cells/mm(3) and plasma viral loads >100,000 copies/mL with no protective HLA alleles (-59 cells/mm(3) per year), whereas the slowest decrease was observed among individuals with CD4 cell counts 201-350 cells/mm(3), plasma viral loads < or =100,000 copies/mL, and a protective HLA allele (-6 cells/mm(3) per year). CONCLUSIONS: The combination of plasma viral load and HLA class I type, but not in vitro HIV-1 protein-specific CD8 T cell responses, differentiates rates of CD4 cell count decrease in patients with chronic subtype-C infection better than either marker alone

Influence of Gag-Protease-Mediated Replication Capacity on Disease Progression in Individuals Recently Infected with HIV-1 Subtype C▿

HLA class I-mediated selection of immune escape mutations in functionally important Gag epitopes may partly explain slower disease progression in HIV-1-infected individuals with protective HLA alleles. To investigate the impact of Gag function on disease progression, the replication capacities of viruses encoding Gag-protease from 60 individuals in early HIV-1 subtype C infection were assayed in an HIV-1-inducible green fluorescent protein reporter cell line and were correlated with subsequent disease progression. Replication capacities did not correlate with viral load set points (P = 0.37) but were significantly lower in individuals with below-median viral load set points (P = 0.03), and there was a trend of correlation between lower replication capacities and lower rates of CD4 decline (P = 0.09). Overall, the proportion of host HLA-specific Gag polymorphisms in or adjacent to epitopes was negatively associated with replication capacities (P = 0.04), but host HLA-B-specific polymorphisms were associated with higher viral load set points (P = 0.01). Further, polymorphisms associated with host-specific protective HLA alleles were linked with higher viral load set points (P = 0.03). These data suggest that transmission or early HLA-driven selection of Gag polymorphisms results in reduced early cytotoxic T-lymphocyte (CTL) responses and higher viral load set points. In support of the former, 46% of individuals with nonprotective alleles harbored a Gag polymorphism exclusively associated with a protective HLA allele, indicating a high rate of their transmission in sub-Saharan Africa. Overall, HIV disease progression is likely to be affected by the ability to mount effective Gag CTL responses as well as the replication capacity of the transmitted virus