St. Croix sheep produce a rapid and greater cellular immune response contributing to reduced establishment of Haemonchus contortus

The objective of this study was to determine the effects of peripheral blood mononuclear cells (PBMC), derived from parasite-resistant St. Croix (STC) hair sheep and parasite-susceptible Suffolk (SUF) sheep, on Haemonchus contortus L stage larval death in vitro, with or without autologous serum. Larval morbidity was quantified by measuring larval ATP concentration following incubation with PBMC. Larvae exposed to either STC- or SUF-derived PBMC had lower ATP than live larvae (0.12 μmol/L ATP and 0.16 μmol/L ATP vs 0.27 μmol/L ATP, respectively) (P<.001) and greater ATP of dead larvae (0.03 μmol/L ATP) (P<.001). Breed differences were observed with addition of autologous serum. Larvae exposed to SUF-derived PBMC with autologous serum were not significantly different from live larval ATP. STC-derived serum did not significantly reduce larval ATP compared to PBMC alone (0.11 μmol/L ATP), but was significantly reduced compared to live larvae (0.22 μmol/L ATP) and SUF-derived PBMC with autologous serum (0.23 μmol/L ATP) (P<.001). These data indicate that a cellular response alone is capable of significantly reducing larval ATP in a breed-independent manner. However, addition of serum to SUF-PBMC failed to reduce larval ATP, indicating breed-dependent humoral response to H. contortus.

Section: Introductionmentioning

confidence: 99%

The effect of ovine peripheral blood mononuclear cells on Haemonchus contortus larval morbidity in vitro

Shepherd

Garza

Greiner

et al. 2017

“…Croix sheep of Caribbean origin have displayed greater resistance to Haemonchus contortus when compared to common commercial breeds . Elevated cellular immune responses and local lymph node hypertrophy of St. Croix sheep have been recently shown to be associated with reduced establishment of H. contortus larvae . To determine the direct effects of immune cells on larval survival, in vitro assays capable of quantifying larval motility should be employed.…”

Section: Introductionmentioning

confidence: 99%

Effects of peripheral blood mononuclear cells on Haemonchus contortus larval motility in vitro

Holt

Shepherd

Ammer

et al. 2015

The objective of this experiment was to determine effects of peripheral blood mononuclear cells (PBMC), derived from parasite-resistant St. Croix (STC) and parasite-susceptible Suffolk (SF) sheep, on motility of Haemonchus contortus L stage larvae in vitro. Peripheral blood mononuclear cells were collected from 10 lambs of each breed, 5 naïve and 5 which had received a priming infection with H. contortus. Larval motility was quantified using a MIF Nikon Sweptfield microscope and NIS Elements AR software, and measurements included path length (PL) (μm), velocity (VEL) (μm/s) and acceleration (ACC) (μm/s ). After 18 h of incubation, PL and VEL were greatest in larvae cultured with SF-derived PMBC and were significantly different from all other groups (P < 0·01). No difference was observed in PL or VEL between larvae exposed to naïve or primed STC-derived PBMC and primed-SF PBMC. Differences in ACC were detected between larvae cultured with primed STC-derived PBMC (10·91 μm/s ) and naïve SF-derived PBMC (45·7 μm/s ) (P = 0·035). These data indicate an innate ability of STC-derived PBMC to severely inhibit larval motility.

“…Neutrophil infiltration to the abomasum has been observed to be increased in St. Croix sheep 3 days after infection with H contortus . In this experiment, we found genes associated with the activation, degranulation and chemotaxis to be upregulated in HcLA cultured PBMC from St. Croix sheep.…”

Section: Discussionmentioning

confidence: 52%

RNA‐Sequencing of ovine PBMC after exposure to Haemonchus contortus larval antigen

Jacobs

Middleton

Greiner

et al. 2020

Self Cite

Mechanisms of immune activation in effector cells during Haemonchus contortus infection in sheep are currently unknown. Microarray experiments have been performed on tissues of H contortus infected sheep of varying parasite resistance during early and late points of infection, but not in immune effector cells. The purpose of this study was to compare early gene activation in peripheral blood mononuclear cells (PBMC) from primed parasite susceptible (Suffolk) and resistant (St. Croix) sheep in response to H contortus larval antigen (HcLA). Peripheral blood mononuclear cells were cultured for 6 hours with HcLA, and RNA‐sequencing was performed. St. Croix PBMC upregulated 499 unique genes in response to HcLA while Suffolk PBMC upregulated 130 unique genes and 25 genes were shared between the two breeds. St. Croix PBMC had increased expression of genes associated with immune function, signal transduction, response to stress and others. In addition, while mechanisms of innate recognition of H contortus are unknown, multiple pattern recognition receptors were found to be upregulated in St. Croix PBMC cultured with HcLA and none were found to be upregulated in Suffolk PBMC. These patterns of immune gene activation may contribute to St. Croix's rapid response and ability to resist H contortus infection.