Characterization of heart macrophages in rhesus macaques as a model to study cardiovascular disease in humans.

Rhesus macaques are physiologically similar to humans and, thus, have served as useful animal models of human diseases including cardiovascular disease. The purpose of this study was to characterize the distribution, composition, and phenotype of macrophages in heart tissues of very young (fetus: 0.5 years, n = 6), young adult (2-12 years, n = 12), and older adult (13-24 years, n = 9) rhesus macaques using histopathology and immunofluorescence microscopy. Results demonstrated that macrophages were uniformly distributed throughout the heart in animals of all age groups and were more prevalent than CD3-positve T-cells and CD20-positive B-cells. Macrophages comprised approximately 2% of heart tissue cells in the younger animals and increased to a mean of nearly 4% in the older adults. CD163-positive macrophages predominated over HAM56-positive and CD206-positive macrophages, and were detected at significantly higher percentage in the animals between 13 and 24 years of age, as well as in heart tissues exhibiting severe histopathology or inflammation in animals of all age groups. In vivo dextran labeling and retention indicated that approximately half of the macrophages were longer lived in healthy adult heart tissues and may comprise the tissue-resident population of macrophages. These results provide a basis for continued studies to examine the specific functional roles of macrophage subpopulations in heart tissues during homeostasis and in cardiovascular disease for then developing intervention strategies.

Mucosal vaccination with a codon-optimized hemagglutinin gene expressed by attenuated Salmonella elicits a protective immune response in chickens against highly pathogenic avian influenza.

The purpose of this study was to evaluate clinical protection from challenge conferred by two attenuated Salmonella enteria serovar typhimurium vaccine strains expressing the hemagglutinin (HA1) gene from a highly pathogenic avian influenza (HPAI) H5N1 (A/whooper swan/Mongolia/3/2005), under control of the anaerobically inducible nir15 promoter. Two-week-old White Leghorn chickens were immunized by oral gavage with one milliliter doses of >109 Salmonella colony-forming units once weekly for 4 weeks prior to challenge. Expression of recombinant protein was confirmed via Western blot. Serum and mucosal gavage samples were collected prior to, and following immunization and antibodies against avian influenza HA were confirmed by Western blot and hemagglutination-inhibition (HI) assay. Chickens were challenged with homologous (A/whooper swan/Mongolia/3/2005), or heterologous (A/Chicken/Queretaro/14588-19/95) HPAI virus strains. Chickens immunized with attenuated Salmonella strains containing plasmid expression vector (pTETnir15HA) demonstrated a statistically significant increase in survival compared to control groups. Results provide evidence of effectiveness of attenuated Salmonella strains for delivery of recombinant avian influenza HA antigens and induction of mucosal and systemic immune responses protective against lethal challenge with HPAI.

Identification and characterization of two distinct bursal B-cell subpopulations following infectious bursal disease virus infection of White Leghorn chickens.

Infectious bursal disease virus (IBDV) is an immunosuppressive virus which primarily infects IgM B-cells in the bursa of Fabricius. Flow cytometric analysis was used to phenotype B-cell populations in the bursa and spleen following IBDV infection. In the bursa, two IgM B-cell subpopulations, designated as A and B, were identified based on cell size and granularity. While both subpopulations differentially expressed IgM and Bu-1b surface markers, both groups displayed major histocompatibility complex class II surface antigens at equal levels. Following IBDV challenge of nonvaccinated birds, the B subpopulation was significantly reduced between 7 and 21 days postchallenge compared to either nonchallenged birds or vaccinated-challenged birds. However, the reduction of subpopulation B in the bursa, following IBDV exposure, did not reduce the levels of total serum IgA, IgG, and IgM, nor did it affect IgG and IgA B-cells in the spleen. Phenotypic analysis of the subpopulations identified differential expression of Lewis(x), IgM, Bu-1b, and MUI78 surface antigens between the subpopulations. Overall, these are the first studies to identify two distinct IgM B-cell subpopulations in the chicken bursa, and the first to describe the decrease in the IgM B-cell population relative to IgA and IgG B-cells following IBDV infection.