BACKGROUND The prevalence of chronic Hepatitis B Virus (HBV) infection is 2-4% in the Pakistani population, defining Pakistan as an intermediate prevalence country. In this study, hepatitis B surface antigen (HBsAg) reactive blood donations were screened using a combination of serological and molecular methods to identify immune escape HBV mutant strains and to determine the HBV genotypes and s...

The Francisella tularensis-containing phagosome (FCP) matures to a late-endosome-like phagosome prior to bacterial escape into the cytosols of macrophages, where bacterial proliferation occurs. Our data show that within the first 15 min after infection of primary human monocyte-derived macrophages (hMDMs), approximately 90% of the FCPs acquire the proton vacuolar ATPase (vATPase) pump and the l...

The relatively simple neural circuit driving the escape response in zebrafish offers an excellent opportunity to study properties of neural circuit formation. The hindbrain Mauthner cell is an essential component of this circuit. Mutations in the zebrafish deadly seven/notch1a (des) gene result in supernumerary Mauthner cells. We addressed whether and how these extra cells are incorporated into...

Cytotoxic T lymphocytes (CTLs) play an important role in shaping HIV-1 infection. In particular, during the first weeks of infection, CTLs select for multiple escape mutations in the infecting HIV population. In recent years, methods have been developed that use intra-patient escape mutation data to estimate rates of escape from CTL selection. The resultant escape rate estimates have been used ...

The dynamics of cellular immunity against pathogens, and its interaction with the human MHC system, is a key area for empirical research, both within individual hosts and in population genetic surveys. However, in contrast with humoral immunity, the dynamics of cellular immunity have not been modeled at the population level. Here, we address this lacuna with a model of recently observed dramati...

Studies of human immunodeficiency virus (HIV) vaccines in animal models suggest that it is difficult to induce complete protection from infection (sterilizing immunity) but that it is possible to reduce the viral load and to slow or prevent disease progression following infection. We have developed an age-structured epidemiological model of the effects of a disease-modifying HIV vaccine that in...

Surveillance data indicate that most circulating A(H1N1)pdm09 influenza viruses have remained antigenically similar since they emerged in humans in 2009. However, antigenic drift is likely to occur in the future in response to increasing population immunity induced by infection or vaccination. In this study, sequential passaging of A(H1N1)pdm09 virus by contact transmission through two independ...

Genotype E hepatitis B virus (HBV) was detected in two Argentine sisters exhibiting an African mitochondrial lineage. One of them (who had been vaccinated against HBV) exhibited anti-HBs cocirculating antibodies without HBsAg escape mutants, while her unvaccinated sister showed a D144A HBsAg escape mutant without anti-HBs antibodies. Both sisters carried an unusual L209V substitution within HBsAg.

Cytosolic bacterial pathogens require extensive metabolic adaptations within the host to replicate intracellularly and cause disease. In phagocytic cells such as macrophages, these pathogens must respond rapidly to nutrient limitation within the harsh environment of the phagosome. Many cytosolic pathogens escape the phagosome quickly (15-60 min) and thereby subvert this host defense, reaching t...