@article{simoes_howard_dean_2012, title={In Vivo Assessment of Natural Killer Cell Responses during Chronic Feline Immunodeficiency Virus Infection}, volume={7}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0037606}, abstractNote={Accumulating evidence suggests that natural killer (NK) cells may have an important role in HIV-1 disease pathogenesis; however, in vivo studies are lacking. Feline immunodeficiency virus (FIV) infection of cats provides a valuable model to study NK cell function in vivo. The immune response against Listeria monocytogenes (Lm) is well characterized, allowing its use as an innate immune probe. We have previously shown that locally delivered IL-15 can improve Lm clearance in FIV-infected animals, and this correlated with an increase in NK cell number. In the present study, chronically FIV-infected and SPF-control cats were challenged with Lm by unilateral subcutaneous injection next to the footpad and then treated with 5-bromo-2′-deoxyuridine (BrdU). The Lm draining and contralateral control lymph nodes were evaluated for NK, NKT, CD4+ and CD8+ T cell number, proliferation, apoptosis, and NK cell function. Listeria monocytogenes burden was also assessed in both control and Lm draining lymph nodes. NK, NKT, CD4+ T and CD8+ T cells in the Lm-challenged lymph node of FIV-infected cats did not increase in number. In addition, after Lm challenge, NK cells from FIV-infected cats did not increase their proliferation rate, apoptosis was elevated, and perforin expression was not upregulated when compared to SPF-control cats. The failure of the NK cell response against Lm challenge in the draining lymph node of FIV-infected cats correlates with the delayed control and clearance of this opportunistic bacterial pathogen.}, number={5}, journal={PLOS ONE}, author={Simoes, Rita D. and Howard, Kristina E. and Dean, Gregg A.}, year={2012}, month={May} }
 @article{howard_reckling_egan_dean_2010, title={Acute mucosal pathogenesis of feline immunodeficiency virus is independent of viral dose in vaginally infected cats}, volume={7}, ISSN={["1742-4690"]}, DOI={10.1186/1742-4690-7-2}, abstractNote={The mucosal pathogenesis of HIV has been shown to be an important feature of infection and disease progression. HIV-1 infection causes depletion of intestinal lamina propria CD4+ T cells (LPL), therefore, intestinal CD4+ T cell preservation may be a useful correlate of protection in evaluating vaccine candidates. Vaccine studies employing the cat/FIV and macaque/SIV models frequently use high doses of parenterally administered challenge virus to ensure high plasma viremia in control animals. However, it is unclear if loss of mucosal T cells would occur regardless of initial viral inoculum dose. The objective of this study was to determine the acute effect of viral dose on mucosal leukocytes and associated innate and adaptive immune responses. Cats were vaginally inoculated with a high, middle or low dose of cell-associated and cell-free FIV. PBMC, serum and plasma were assessed every two weeks with tissues assessed eight weeks following infection. We found that irrespective of mucosally administered viral dose, FIV infection was induced in all cats. However, viremia was present in only half of the cats, and viral dose was unrelated to the development of viremia. Importantly, regardless of viral dose, all cats experienced significant losses of intestinal CD4+ LPL and CD8+ intraepithelial lymphocytes (IEL). Innate immune responses by CD56+CD3- NK cells correlated with aviremia and apparent occult infection but did not protect mucosal T cells. CD4+ and CD8+ T cells in viremic cats were more likely to produce cytokines in response to Gag stimulation, whereas aviremic cats T cells tended to produce cytokines in response to Env stimulation. However, while cell-mediated immune responses in aviremic cats may have helped reduce viral replication, they could not be correlated to the levels of viremia. Robust production of anti-FIV antibodies was positively correlated with the magnitude of viremia. Our results indicate that mucosal immune pathogenesis could be used as a rapid indicator of vaccine success or failure when combined with a physiologically relevant low dose mucosal challenge. We also show that innate immune responses may play an important role in controlling viral replication following acute mucosal infection, which has not been previously identified.}, journal={RETROVIROLOGY}, author={Howard, Kristina E. and Reckling, Stacie K. and Egan, Erin A. and Dean, Gregg A.}, year={2010}, month={Jan} }
 @article{zurney_howard_sherry_2007, title={Basal expression levels of IFNAR and Jak-STAT components are determinants of cell-type-specific differences in cardiac antiviral responses}, volume={81}, ISSN={["0022-538X"]}, DOI={10.1128/JVI.01172-07}, abstractNote={ABSTRACT}, number={24}, journal={JOURNAL OF VIROLOGY}, author={Zurney, Jennifer and Howard, Kristina E. and Sherry, Barbara}, year={2007}, month={Dec}, pages={13668–13680} }
 @article{howard_burkhard_2007, title={FIV infection induces unique changes in phenotype and cellularity in the medial iliac lymph node and intestinal IEL}, volume={23}, ISSN={["1931-8405"]}, DOI={10.1089/aid.2006.0025}, abstractNote={Studies of human immunodeficiency virus-1 (HIV-1)-infected patients and simian immunodeficiency virus (SIV)-infected macaques have identified profound depletion of CD4(+) T cells and expansion of CD8(+) T cells in the gastrointestinal lamina propria. Less attention has been given to CD8(+) intraepithelial lymphocytes (IEL), and no studies have concurrently examined inductive sites such as draining lymph nodes. Our preliminary data in the feline immunodeficiency virus (FIV) animal model suggested additional changes in IEL, and marked differences in the responses of lymph nodes draining different mucosal sites. To address this, we quantified the absolute leukocyte yield and examined the phenotype of cells from small intestinal IEL, mesenteric lymph node (MLN), and medial iliac lymph node (ILN) from chronically FIV-infected cats. The cellularity of the ILN was increased 530% in FIV-infected animals with an expansion of CD62L(+) cells, suggesting an increased population of naive T cells. The number of CD4(+), as well as CD8(+), T cells was increased in the ILN, resulting in a CD4:CD8 ratio greater than 1:1. In contrast, reduced cellularity, specific loss of CD4(+) T cells, and inversion of the CD4:CD8 ratio was observed in the MLN, which drains the intestine. In IEL, loss of CD8alpha, CD8beta, and CD4-expressing T cells was found in FIV-infected cats. Furthermore, expression intensity of CD8alpha and CD5, markers known to be important in T cell function, was markedly decreased on IEL. These findings expand the array of immune alterations induced by lentiviral infection and indicate that characterization of multiple mucosal sites will be necessary to fully understand the pathogenesis of HIV-1 infection.}, number={5}, journal={AIDS RESEARCH AND HUMAN RETROVIRUSES}, author={Howard, Kristina E. and Burkhard, Mary Jo}, year={2007}, month={May}, pages={720–728} }
 @article{howard_burkhard_2007, title={Mucosal challenge with cell-associated or cell-free feline immunodeficiency virus induces rapid and distinctly different patterns of phenotypic change in the mucosal and systemic immune systems}, volume={122}, ISSN={["1365-2567"]}, DOI={10.1111/j.1365-2567.2007.02673.x}, abstractNote={Summary}, number={4}, journal={IMMUNOLOGY}, author={Howard, Kristina E. and Burkhard, Mary Jo}, year={2007}, month={Dec}, pages={571–583} }
 @article{howard_fisher_dean_burkhard_2005, title={Methodology for isolation and phenotypic characterization of feline small intestinal leukocytes}, volume={302}, ISSN={["1872-7905"]}, DOI={10.1016/j.jim.2005.04.019}, abstractNote={Critical assessment of intestinal immune responses requires the ability to characterize leukocytes from different anatomic locations as leukocytes from inductive sites such as Peyer's patches and lymphoid follicles vary significantly from their effector counterparts, intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL). This study describes (1) methods developed to isolate specific intestinal leukocyte populations with high yield and purity, (2) difficulties encountered in establishing a panel of monoclonal antibodies to assess phenotype, and (3) the phenotypic characterization of effector and inductive sites in the feline small intestine. We found that the phenotypic distribution of feline intestinal leukocytes was similar to that found in other species such as humans, macaques and mice. The majority of IEL were CD5(+) T-cells with less than 7% B-cells. CD8(+) T-cells comprised approximately 60% of the IEL with roughly half displaying CD8alphaalpha homodimers. Approximately 10% of IEL were CD4(+) T-cells. In the LPL, CD4(+) T-cells predominated at 42%, with 33% CD8(+) T-cells and 10% B-cells. As would be expected, B-cells predominated in Peyer's patches with 40% B-cells, 28% CD4(+) T-cells and 20% CD8(+) T-cells. Increased MHCII expression was found in the Peyer's patches as compared to the IEL and LPL. B7.1 expression was significantly higher in mucosal leukocyte populations as compared to organized lymphoid tissue in the periphery with expression detected on 65% of IEL and 53% of LPL. Plasma cells were found in all regions of small intestine examined with greater numbers in lamina propria and Peyer's patches. Lymphoblasts were only identified in inductive tissue. In general, no differences were found between the phenotype of mucosal leukocyte populations from specific pathogen free or random source cats. However, the percentage of CD4(+) CD25(+) T-cells was significantly greater in both IEL and LPL from random source animals. This study provides techniques and a baseline from which future studies of the feline intestinal immune system can be conducted.}, number={1-2}, journal={JOURNAL OF IMMUNOLOGICAL METHODS}, author={Howard, KE and Fisher, IL and Dean, GA and Burkhard, MJ}, year={2005}, month={Jul}, pages={36–53} }
 @article{ignacio_nordone_howard_dean_2005, title={Toll-like receptor expression in feline lymphoid tissues}, volume={106}, ISSN={["1873-2534"]}, DOI={10.1016/j.vetimm.2005.02.022}, abstractNote={Toll-like receptors (TLRs) are germline-encoded pattern recognition receptors (PRRs) that activate the innate immune system. While it is clear that TLRs are important in the immune response against pathogens, they may also be exploited by some pathogens. Our objective is to determine whether feline immunodeficiency virus (FIV) infection affects TLR expression or function thereby resulting in innate immune dysfunction. To this end, we cloned partial sequences for feline TLRs 1–3, 5–8, and developed real-time PCR assays to quantify feline TLRs 1–9. TLR expression was quantified in normal cat lymphoid tissues, purified lymphocyte subsets, and FIV-infected cell lines. Different expression patterns of TLRs were found in spleen, mesenteric lymph node, retropharyngeal lymph node, thymus, intestinal intraepithelial lymphocytes, and lamina propria lymphocytes. B lymphocytes, CD4+ T cells, and CD8+ T cells all expressed TLRs 2–5, 7–9; however, the relative levels of expression varied among lymphocyte phenotypes. Infection of cell lines with FIV resulted in altered TLR expression levels that differed depending on cell type. These results demonstrate that tissue distribution of TLRs is associated with the immunological role of a particular tissue, that lymphocytes may also express these ‘innate immune’ receptors, and that FIV infection can alter TLR expression.}, number={3-4}, journal={VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY}, author={Ignacio, G and Nordone, S and Howard, KE and Dean, GA}, year={2005}, month={Jul}, pages={229–237} }