Impaired antibody response and phagocytosis in goats fed a diet low in cobalt

Comparison of the oxidative respiratory burst and mitogen-induced leukocyte responses of camels, goats, sheep, and cows

Background and Aim:

The reports from the Ministry of Agriculture and Fisheries suggest that camels suffer less compared to goats, sheep, and cows from a number of common infectious diseases in Oman. However, there is no immunological evidence to substantiate this claim. This present study is, therefore, an attempt to study the immunological responses of camels, goats, sheep, and cows by comparing their oxidative respiratory burst of peripheral blood leukocytes (PBLs) as a marker of innate immunity occurring during phagocytosis and the mitogenic responses of their peripheral blood mononuclear leukocytes (PBMLs) as a marker of their adaptive immune response.

Materials and Methods:

Ten female adult animals (n = 10) were selected from each species (goats, sheep, and cows). The goats, sheep, and cows were maintained at the Agricultural Experiment Station, while camels were kept at the Royal Camel Corps (RCC). Blood samples were collected from the jugular vein in 7 mL of heparin and ethylenediaminetetraacetic acid vacutainer tubes. The oxidative respiratory burst of PBLs was measured using a chemiluminescence (CL) assay. Reactants consisted of 75 mL of whole blood diluted (1:50), 75 mL of luminol/isoluminol, and 75 mL of zymosan opsonized with non-heat inactivated serum/heat-inactivated serum or non-opsonized zymosan. CL responses were measured as relative light units and expressed as the mean count per minute and peak CL values. The mitogenic response of PBMLs to concanavalin A (Con-A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) was tested using a WST-8 assay and read spectrophotometrically at 450 nm.

Results:

The present findings showed that camel PBLs generate significantly higher CL responses, both intracellularly as well as extracellularly, with zymosan opsonized with autologous serum. Camel PBLs demonstrated a significantly higher (p = 0.001) response when stimulated with zymosan opsonized with heat-inactivated serum compared to those of goat, sheep, and cow lymphocytes from camels exhibited significantly higher (p = 0.001) stimulation indices (SI) with Con-A, PHA, and PWM.

Conclusion:

The present study suggests that camels are capable of mounting both superior innate as well as adaptive immune responses and provide immunological evidence supporting the belief of some authors, who have proposed that camels are less susceptible to a number of common infectious diseases than other domesticated ruminants.

Vitamin B12 deficiency in newly weaned goat kids associated with clinical infection with Eimeria arloingi

A severe outbreak of diarrhea associated with poor growth was reported in ten newly weaned goat kids that originated from a research farm (Group A). Two of these kids underwent necropsy examination. Five goat kids of the same age maintained in the same pen showed no clinical signs (Group B). The clinical, gross pathological and histopathological features of the clinically sick animals were consistent with severe coccidiosis. Group A animals had significantly lower levels of serum vitamin B12 (<200 pg/ml) compared with group B animals (2000 pg/ml). In addition, kids belonging to group A had significantly higher Eimeria arloingi oocysts per gram (OPG) of faeces (101,400/g) compared with kids of group B (9,154/g). Microscopy and molecular tools (18S rRNA and COI genes) confirmed that the goat kids were infected with the caprine protozoan parasite E. arloingi. This study provides a definitive association between low levels of serum vitamin B12 and clinical E. arloingi infection, and also provides support to our previous studies that demonstrated how low levels of serum vitamin B12 leads to an impairment of neutrophil function and thereby potential lowered immunity to pathogens.