Dual Transcriptomics To Determine Gamma Interferon-Independent Host Response to Intestinal Cryptosporidium parvum Infection.

Animals with a chronic infection of the parasite Toxoplasma gondii are protected against lethal secondary infection with other pathogens. Our group previously determined that soluble T. gondii antigens (STAg) can mimic this protection and be used as a treatment against several lethal pathogens.

Proteomic and transcriptomic analyses of early and late-chronic Toxoplasma gondii infection shows novel and stage specific transcripts.

Background: The protozoan pathogen Toxoplasma gondii has the unique ability to develop a chronic infection in the brain of its host by transitioning from the fast growing tachyzoite morphology to latent bradyzoite morphology. A hallmark of the bradyzoite is the development of neuronal cysts that are resilient against host immune response and current therapeutics. The bradyzoite parasites within the cyst have a carbohydrate and protein-rich wall and a slow-replication cycle, allowing them to remain hidden from the host.

Transcriptional Analysis Shows a Robust Host Response to during Early and Late Chronic Infection in Both Male and Female Mice.

The long-term host effects caused by the protozoan parasite are poorly understood. High-throughput RNA sequencing analysis previously determined that the host response in the brain was greater and more complex at 28 days than at 10 days postinfection. Here, we analyzed the host transcriptional profile of age- and sex-matched mice during very early (21 days), early (28 days), mid (3 months), and late (6 months) chronic infection.

O-Mannosylation of Proteins Enables Yeast Survival at Mammalian Body Temperatures.

The ability to grow at mammalian body temperatures is critical for pathogen infection of humans. For the thermally dimorphic fungal pathogen , elevated temperature is required for differentiation of mycelia or conidia into yeast cells, a step critical for invasion and replication within phagocytic immune cells. Posttranslational glycosylation of extracellular proteins characterizes factors produced by the pathogenic yeast cells but not those of avirulent mycelia, correlating glycosylation with infection.

Eng1 and Exg8 Are the Major β-Glucanases Secreted by the Fungal Pathogen .

Fungal cell walls contain β-glucan polysaccharides that stimulate immune responses when recognized by host immune cells. The fungal pathogen minimizes detection of β-glucan by host cells through at least two mechanisms: concealment of β-glucans beneath α-glucans and enzymatic removal of any exposed β-glucan polysaccharides by the secreted glucanase Eng1. yeasts also secrete the putative glucanase Exg8, which may serve a similar role as Eng1 in removing exposed β-glucans from the yeast cell surface.

The Eng1 β-Glucanase Enhances Histoplasma Virulence by Reducing β-Glucan Exposure.

Unlabelled: The fungal pathogen Histoplasma capsulatum parasitizes host phagocytes. To avoid antimicrobial immune responses, Histoplasma yeasts must minimize their detection by host receptors while simultaneously interacting with the phagocyte. Pathogenic Histoplasma yeast cells, but not avirulent mycelial cells, secrete the Eng1 protein, which is a member of the glycosylhydrolase 81 (GH81) family.

Histoplasma capsulatum surmounts obstacles to intracellular pathogenesis.

The fungal pathogen Histoplasma capsulatum causes respiratory and disseminated disease, even in immunocompetent hosts. In contrast to opportunistic pathogens, which are readily controlled by phagocytic cells, H. capsulatum yeasts are able to infect macrophages, survive antimicrobial defenses, and proliferate as an intracellular pathogen.

Histoplasma capsulatum depends on de novo vitamin biosynthesis for intraphagosomal proliferation.

During infection of the mammalian host, Histoplasma capsulatum yeasts survive and reside within macrophages of the immune system. Whereas some intracellular pathogens escape into the host cytosol, Histoplasma yeasts remain within the macrophage phagosome. This intracellular Histoplasma-containing compartment imposes nutritional challenges for yeast growth and replication.