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Articles by Angela Pollard in JoVE
JoVE Immunology and Infection
Aktif Kemik İliği türetilen Makrofajlar ve Bradyzoite Koşullar Toxoplasma gondii Kist Duvar Oluşumu
Department of Medical Microbiology and Immunology, University of Wisconsin
Toxoplasma gondii doku kültürü modelleri taklit edilebilmektedir çevresel strese yanıt olarak bir kist formuna dönüşür. Bu video makrofajlar kemik iliği kaynaklı aktive veya fibroblast hücreleri büyüme orta pH değerini değiştirerek kist oluşumunu incelemek için teknikler gösterilmiştir.
Other articles by Angela Pollard on PubMed
Highly Polymorphic Family of Glycosylphosphatidylinositol-anchored Surface Antigens with Evidence of Developmental Regulation in Toxoplasma Gondii
The life cycle of the apicomplexan parasite Toxoplasma gondii requires that an infectious cyst develop and be maintained throughout the life of the host. The molecules displayed on the parasite surface are important in controlling the immune response to the parasite. T. gondii has a superfamily of glycosylphosphatidylinositol (GPI)-anchored surface antigens, termed the surface antigen (SAG) and SAG-related surface antigens, that are developmentally regulated during infection. Using a clustering algorithm, we identified a new family of 31 surface proteins that are predicted to be GPI anchored but are unrelated to the SAG proteins, and thus we named these proteins SAG-unrelated surface antigens (SUSA). Analysis of the single nucleotide polymorphism density showed that the members of this family are the most polymorphic genes within the T. gondii genome. Immunofluorescence of SUSA1 and SUSA2, two members of the family, revealed that they are found on the parasite surface. We confirmed that SUSA1 and SUSA2 are GPI anchored by phospholipase cleavage. Analysis of expressed sequence tags (ESTs) revealed that SUSA1 had 22 of 23 ESTs from chronic infection. Analysis of mRNA and protein confirmed that SUSA1 is highly expressed in the chronic form of the parasite. Sera from mice with chronic T. gondii infection reacted to SUSA1, indicating that SUSA1 interacts with the host immune system during infection. This group of proteins likely represents a new family of polymorphic GPI-anchored surface antigens that are recognized by the host's immune system and whose expression is regulated during infection.
Structural Characterization of Haemophilus Parainfluenzae Lipooligosaccharide and Elucidation of Its Role in Adherence Using an Outer Core Mutant
The opportunistic pathogen Haemophilus parainfluenzae is a gram-negative bacterium found in the oropharynx of humans. Haemophilus parainfluenzae is a member of the Pasteurellaceae family in which it is most closely related to Haemophilus sengis and Actinobacillus. Characterization of surface displayed lipooligosaccharide has identified components that are crucial in adherence. We examined the oligosaccharide structure of lipooligosaccharide from 2 clinical isolates of H. parainfluenzae. Core oligosaccharide was isolated by standard methods from purified lipooligosaccharide. Structural information was established by a combination of monosaccharide and methylation analyses, nuclear magnetic resonance spectroscopy, and mass spectrometry revealing the following structures: R-(1-6)-beta-Glc-(1-4)-D,D-alpha-Hep-(1-6)-beta-Glc-(1-4)- substituting a tri-heptose-Kdo inner core of L,D-alpha-Hep-(1-2)-L,D-alpha-Hep-(1-3)-L,D-alpha-Hep-(1-5)-alpha-Kdo at the 4-position of the proximal L,D-alpha-Hep residue to Kdo, and with a PEtn residue at the 6-position of the central L,D-alpha-Hep residue. In strain 4282, the R substituent is beta-galactose and in strain 4201 there is no substituent at the distal glucose. These analyses have revealed that multiple structural aspects of H. parainfluenzae lipooligosaccharide are comparable with nontypeable Haemophilus influenzae lipooligosaccharide. This study also identified a galactan in strain 4201 and a glucan in strain 4282. Haemophilus parainfluenzae was shown to adhere to a bronchial epithelial cell line to the same degree as nontypeable H. influenzae. However, an H. parainfluenzae mutant lacking the outer core of the lipooligosaccharide showed diminished adherence to the epithelial cells, suggesting that H. parainfluenzae lipooligosaccharide plays a role in tissue colonization.
A Transmembrane Domain-containing Surface Protein from Toxoplasma Gondii Augments Replication in Activated Immune Cells and Establishment of a Chronic Infection
Toxoplasma gondii mutants identified as defective in the establishment of chronic infection were screened to isolate those specifically impaired in their ability to replicate within activated macrophages. One of the identified mutants contains an insertion in the hypothetical gene TGME49_111670. Genetic complementation restores the ability of the mutant to replicate in immune cells and produce cysts in the brains of mice. While the mutant is more sensitive to nitric oxide than is its parental strain, it is not defective in its ability to suppress nitric oxide. The disrupted protein has no significant homology to proteins with known functions, but is predicted to have one transmembrane domain. Immunofluorescence shows the protein on the parasite surface, even in activated macrophages, colocalizing with a tachyzoite surface antigen, SAG1, and oriented with its C-terminal end external. Western analysis reveals that the protein is downregulated in bradyzoites. Despite the tachyzoite specificity of this protein, mice infected with the mutant succumb to acute infection similarly to those infected with the parent strain. Serum samples from mice with chronic T. gondii infection react to a polypeptide from TGME49_11670, indicating that the protein is seen by the immune system during infection. This study is the first to characterize a T. gondii surface protein that contains a transmembrane domain and show that the protein contributes to parasite replication in activated immune cells and the establishment of chronic infection.
The Role of Specific Toxoplasma Gondii Molecules in Manipulation of Innate Immunity
Infection with the parasite Toxoplasma gondii stimulates an innate immune response in the host. T. gondii also induces alterations in infected monocytes and dendritic cells that probably contribute to its ability to disseminate and ultimately to establish persistent infection. Recent progress has linked specific parasite molecules to immune stimulation or the ability of the parasite to subvert intracellular signaling pathways in infected cells to evade immunity.
