Frequency of IFNγ-producing T cells correlates with seroreactivity and activated T cells during canine Trypanosoma cruzi infection

Abstract

Vaccines to prevent Trypanosoma cruzi infection in humans or animals are not available, and in many settings, dogs are an important source of domestic infection for the insect vector. Identification of infected canines is crucial for evaluating peridomestic transmission dynamics and parasite control strategies. As immune control of T. cruzi infection is dependent on humoral and cell-mediated immune responses, we aimed to define a serodiagnostic assay and T cell phenotypic markers for identifying infected dogs and studying the canine T. cruzi-specific immune response. Plasma samples and peripheral blood mononuclear cells (PBMCs) were obtained from forty-two dogs living in a T. cruzi-endemic region. Twenty dogs were known to be seropositive and nine seronegative by conventional serologic tests two years prior to our study. To determine canine seroreactivity, we tested sera or plasma samples in a multiplex bead array against eleven recombinant T. cruzi proteins. Ninety-four percent (17/18) of dogs positive by multiplex serology were initially positive by conventional serology. The frequency of IFNγ-producing cells in PBMCs responding to T. cruzi correlated to serological status, identifying 95% of multiplex seropositive dogs. Intracellular staining identified CD4+ and CD8+ T cell populations as the sources of T. cruzi lysate-induced IFNγ. Low expression of CCR7 and CD62L on CD4+ and CD8+ T cells suggested a predominance of effector/effector memory T cells in seropositive canines. These results are the first, to our knowledge, to correlate T. cruzi-specific antibody responses with T cell responses in naturally infected dogs and validate these methods for identifying dogs exposed to T. cruzi.

Multi-color flow cytometry for evaluating age-related changes in memory lymphocyte subsets in dogs

“…Also, CTL2.58 positivity associated with activated T cells as it increased with stimulation(Hartley and Tarleton, 2015). Subsequently, these investigators reported decreased CCR7+ and CD62L+ T cells in Argentinean dogs exposed to Trypanosoma cruzi compared to dogs from the United States, although no differences in CCR7, CD62L and CTL2.58 expression were detected between T. cruzi seropositive and seronegative dogs(Hartley et al, 2014). Findings by Rothe, et al indirectly suggested that canine CD44+CD62L- T cells might have functional characteristics consistent with that of human EM T cells based on mitogen-induced IFN-g and CD25 expression observed for a highly activated canine CD4+CD8+ T cell subset that predominantly express this EM-like phenotype (Rothe et al, 2017).…”

“…In pigs, another relevant large animal model, T helper cell subsets have been proposed to consist of naïve (CD8α-CD27+), CM (CD8α+CD27+), and EM (CD8α+CD27-), with CD45RC and swine leukocyte antigen-DR (SLA-DR) also useful in enriching for functionally distinct subsets(Reutner et al, 2013). In dogs, combinations of Ig-CCL19, anti-CD62L and anti-CTL2.58, as well as anti-CD44 with anti-CD62L, have been used to identify naïve, CM, EM and TEMRA T cells(Hartley et al, 2014; Rothe et al, 2017), although the function of these cell subsets has not yet been verified and unfortunately many of these antibodies are not conjugated, or commercially available.…”

OMIP‐065: Dog Immunophenotyping and T‐Cell Activity Evaluation with a 14‐Color Panel

“…Dogs represent an attractive outbred species that experience spontaneous development of many diseases such as cancer (2,3), autoimmunity (4,5), allergies (6), and infectious diseases (7,8) in the setting of an intact immune system on a compressed timeline due to their comparatively short life spans. The characterization of leukocyte subset distribution in healthy dogs provides the basis to study changes in dogs affected by diseases.…”

Echocardiographic Findings in Canine Model of Chagas Disease Immunized with DNA Trypanosoma cruzi Genes

“…This technique has been shown to be repeatable and reproducible in dogs [19]. In addition, the canine model has gained wide acceptance as another experimental model to study a wide variety of conditions associated with ChD; however, the development of vaccines as a prophylactic method has not been widely addressed [20][21][22][23][24][25][26][27][28][29][30].…”