Host nuclear genotype influences phenotype of a conditional mutualist symbiont.

Arthropods commonly carry maternally inherited intracellular bacterial symbionts that may profoundly influence host biology and evolution. The intracellular symbiont Rickettsia sp. nr. bellii swept rapidly into populations of the sweetpotato whitefly Bemisia tabaci in the south-western USA. Previous laboratory experiments showed female-bias and fitness benefits were associated with Rickettsia infection, potentially explaining the high frequencies of infection observed in field populations, but the effects varied with whitefly genetic line. Here, we explored whether host extranuclear or nuclear genes influenced the variation in the Rickettsia-host phenotype in two genetic lines of the whitefly host, each with Rickettsia-infected and uninfected sublines. Introgression between the Rickettsia-infected subline of one genetic line and the Rickettsia-uninfected subline of the other was used to create two new sublines, each with the maternally inherited extranuclear genetic lineages of one line (Rickettsia, two other symbionts and the mitochondria) and the nuclear genotype of the other. Performance assays comparing the original and new lines showed that in addition to Rickettsia, the interaction of Rickettsia infection with host nuclear genotype influenced development time and the sex ratio of the progeny, whereas the extranuclear genotype did not. Host nuclear genotype, but not extranuclear genotype, also influenced the titre of Rickettsia. Our results support the hypothesis that differences in host nuclear genotype alone may explain considerable within-population variation in host-symbiont phenotype and may contribute to the observed variation in Rickettsia-whitefly interactions worldwide.

Opportunities and barriers for implementation of integrated TB and HIV care in lower level health units: experiences from a rural western Ugandan district.

BACKGROUND: As countries with a high burden of TB and HIV roll out integrated TB/HIV care, there is need to assess possibility of lower level health units treating TB to provide integrated TB/HIV care. OBJECTIVE: To determine barriers and opportunities for provision of integrated TB/HIV care in lower level health units offering TB treatment in Mbarara district, Uganda. METHODS: Conducted key informant interviews, interviewed health workers and observed services offered. RESULTS: 22 health units were assessed and 88 health workers were interviewed. Of the 18 health units mandated to offer laboratory services, 55.6% and 38.9% were able to offer rapid HIV-testing and ZN staining respectively. Understaffing, lack of capacity to diagnose HIV and TB, lack of guidelines to inform care options of TB/HIV co-infected patients and insufficient knowledge and skills among health workers towards provision of integrated TB/HIV care were mentioned as barriers to provision of integrated TB/HIV services. CONCLUSION: To offer integrated TB/HIV services at lower level health units currently offering TB stand alone services, there is need to address gaps in knowledge and skills among health workers, laboratory diagnostics, staffing levels, medical supplies and infrastructure.