Bacillus anthracis Spore Surface Protein BclA Mediates Complement Factor H Binding to Spores and Promotes Spore Persistence

Spores of Bacillus anthracis, the causative agent of anthrax, are known to persist in the host lungs for prolonged periods of time, however the underlying mechanism is poorly understood. In this study, we demonstrated that BclA, a major surface protein of B. anthracis spores, mediated direct binding of complement factor H (CFH) to spores. The surface bound CFH retained its regulatory cofactor activity resulting in C3 degradation and inhibition of downstream complement activation. By comparing results from wild type C57BL/6 mice and complement deficient mice, we further showed that BclA significantly contributed to spore persistence in the mouse lungs and dampened antibody responses to spores in a complement C3-dependent manner. In addition, prior exposure to BclA deletion spores (ΔbclA) provided significant protection against lethal challenges by B. anthracis, whereas the isogenic parent spores did not, indicating that BclA may also impair protective immunity. These results describe for the first time an immune inhibition mechanism of B. anthracis mediated by BclA and CFH that promotes spore persistence in vivo. The findings also suggested an important role of complement in persistent infections and thus have broad implications

International terrorism, domestic coverage? How terrorist attacks are presented in the news of CNN, Al Jazeera, the BBC, and ARD

The article analyzes to what extent news reporting on terrorist attacks globalized, regionalized, or country specific. We compare coverage on four terrorist incidents in the main news shows of the US edition of CNN, of Al Jazeera’s Arabic language service, of the British BBC, and of the German ARD. The analysis shows cross-national similarities in several dimensions: the analyzed media devote nearly identical amounts of attention to the four events, employ similar stylistic devices to describe them, and evaluate them similarly. At the same time, there are notable differences. These differences are not found between Western channels and Al Jazeera – as proponents of a ‘clash of civilizations’ might expect – but between CNN and Al Jazeera on the one hand, and the BBC and ARD on the other. The former interpret the attacks as an expression of a global “war on terror”, whereas the latter see them as criminal attacks by a few individuals against the human civilization itself