Bovine sarcocystosis: How parasites negatively affect growth

Presence of Sarcocystis sybillensis in Japanese sika deer (Cervus nippon) captured in its native territory and its phylogenetic relationship with Sarcocystis nipponi

The first study reporting the morphological characterization of Sarcocystis sybillensis was performed in 1983; however, without any molecular analysis. Sarcocystis nipponi has been recently described as a species synonymic to S. sybillensis. We reconfirmed the presence of S. sybillensis in Japanese sika deer (Cervus nippon) captured in its native territory; and performed its molecular and phylogenetic characterization. The morphological characteristics of the sarcocysts were consistent with those of S. nipponi and S. sybillensis described in the first report. However, the nucleotide sequence of 18S rRNA gene of S. sybillensis showed only 91.9% identity to that of S. nipponi, suggesting low homology among the concerned Sarcocystis spp. Accordingly, S. sybillensis was found to occupy a clade distinct from that of S. nipponi in a phylogenetic tree of Sarcocystis. Therefore, the present study provides essential information on 18S rRNA-based molecular characterization of S. sybillensis and disproves the existing notion of morphology-based species synonymity of S. sibillensis and S. nipponi. These results also suggest that S. sybillensis belongs to type 2 Sarcocystis.

Muscular Sarcocystosis in Sheep Associated With Lymphoplasmacytic Myositis and Expression of Major Histocompatibility Complex Class I and II

Sarcocystosis is a protozoal disease affecting a wide range of animals. The aims of this study were to characterize the following in sheep: (1) the muscle pathology in Sarcocystis infection, (2) the inflammatory infiltrate and its relationship to severity of infection, and (3) immune markers expressed by parasitized muscle fibers and parasitic cysts. Skeletal muscle samples from 78 sheep slaughtered in southern Italy were snap frozen and analyzed by histopathology, immunohistochemistry, and immunofluorescence. Polymerase chain reaction (PCR) and sequencing were used for Sarcocystis species identification. All 40 muscle samples tested were PCR-positive for Sarcocystis tenella. Histologically, cysts were identified in 76/78 cases (97%), associated with an endomysial infiltrate of lymphocytes and plasma cells. The T cells were predominantly CD8+, with fewer CD4+ or CD79α+ cells. Eosinophils were absent. Notably, sarcolemmal immunopositivity for major histocompatibility complex (MHC) I and II was found in 76/78 cases (97%) and 75/78 cases (96%), respectively, both in samples with and in those without evident inflammatory infiltrate. The number of cysts was positively correlated with inflammation. In addition, MHC I was detected in 55/78 cyst walls (72%), and occasionally co-localized with the membrane-associated protein dystrophin. The findings suggest that muscle fibers respond to the presence of cysts by expression of MHC I and II. The possible role of MHC I and II in the inflammatory response and on the cyst wall is also discussed.

Morphological and molecular characterization of Sarcocystis taeniata and Sarcocystis pilosa n. sp. from the sika deer (Cervus nippon) in Lithuania

The diaphragm muscles of eight sika deer (Cervus nippon) bred in Lithuania were examined for Sarcocystis cysts. Two Sarcocystis species, Sarcocystis taeniata, which were previously reported in Canadian moose (Alces alces) and Argentinean red deer (Cervus elaphus), and Sarcocystis pilosa n. sp. were described using light microscopy (LM), transmission electron microscopy (TEM), 18S ribosomal DNA (rDNA), and subunit I of cytochrome c oxidase (cox1) sequences analysis. By LM, cysts of S. taeniata were 424.8 × 57.9 (200-837 × 30-100) μm in size and had a thin (up to 1 μm) and smooth cyst wall, while short ribbon-like protrusions arising from broadened cone-shaped bases were seen under TEM. Cysts of S. pilosa (by LM) were ribbon-shaped, measured 848.5 × 63.8 (350-1700 × 30-125) μm and had thin 7-8-μm long hair-like protrusions. By TEM, cyst wall was type 7a-like; protrusions arose from 0.3 μm wide dome-shaped base with minute indentations of the parasitophorous vacuolar membrane near it, the surface of protrusions seemed to be smooth, and the ground substance layer was thin (0.18-0.22 μm). The 18S rDNA, in contrast to the cox1, lacked variability to discriminate S. pilosa from closely related Sarcocystis hjorti from the red deer and moose. S. taeniata, but not S. pilosa, showed a considerable intraspecific variation in both genes analyzed. The phylogenetic analyses based on 18S rDNA and cox1 sequences suggest that canids are definitive hosts of both S. taeniata and S. pilosa. This paper represents the first identification of Sarcocystis species in the sika deer by morphological and molecular methods.

Prevalence of Sarcocystis spp. and Hammondia spp. microcysts in esophagus tissue of sheep and cattle, emphasized on their morphological differences

Sarcocystis and Hammondia are two obligatory protozoan parasites. These genera belong to cyst-forming coccidia group of the phylum Apicomplexa. They both need two different hosts to complete their life cycles. Felids and canids can act as definitive hosts, while herbivores, such as sheep and cattle, are the most important intermediate hosts. Reports verify that no important disease has been caused by Hammondia spp.; on the other hand, Sarcocystis spp. can cause some severe infectious disease in livestock industry such as abortion. Economic losses are another concern due to carcass condemnation during meat inspection in abattoirs and decrease in the quality and quantity of milk and wool production. Due to the Sarcocystis and Hammondia tissue cysts being similar, the distinction between these different genera is so important. In this study, the prevalence of Sarcocystis and Hammondia in the esophagus tissue of sheep and cattle slaughtered in one of the industrial abattoir in Iran was reported and an easy and rapid method for accurate diagnosing of Sarcocystis and Hammondia bradyzoites was explained.

Molecular characterization of Sarcocystis species from Polish roe deer based on ssu rRNA and cox1 sequence analysis

Sarcocysts from four Polish roe deer were collected and examined by light microscopy, small subunit ribosomal RNA (ssu rRNA), and the subunit I of cytochrome oxidase (cox1) sequence analysis. This resulted in identification of Sarcocystis gracilis, Sarcocystis oviformis, and Sarcocystis silva. However, we were unable to detect Sarcocystis capreolicanis, the fourth Sarcocystis species found previously in Norwegian roe deer. Polish sarcocysts isolated from various tissues differed in terms of their shape and size and were larger than the respective Norwegian isolates. Analysis of ssu rRNA gene revealed the lack of differences between Sarcocystis isolates belonging to one species and a very low degree of genetic diversity between Polish and Norwegian sarcocysts, ranging from 0.1 % for Sarcocystis gracilis and Sarcocystis oviformis to 0.44 % for Sarcocystis silva. Contrary to the results of the ssu rRNA analysis, small intraspecies differences in cox1 sequences were found among Polish Sarcocystis gracilis and Sarcocystis silva isolates. The comparison of Polish and Norwegian cox1 sequences representing the same Sarcocystis species revealed similar degree of sequence identity, namely 99.72 % for Sarcocystis gracilis, 98.76 % for Sarcocystis silva, and 99.85 % for Sarcocystis oviformis. Phylogenetic reconstruction and genetic population analyses showed an unexpected high degree of identity between Polish and Norwegian isolates. Moreover, cox1 gene sequences turned out to be more accurate than ssu rRNA when used to reveal phylogenetic relationships among closely related species. The results of our study revealed that the same Sarcocystis species isolated from the same hosts living in different geographic regions show a very high level of genetic similarity.

Bidirectional communication: Growth and immunity in domestic livestock1,2,3,4

Evidence continues to mount supporting the existence of a bidirectional communication network between the immune system and the somatotropic axis in a variety of species. For more than 4 decades, researchers have sought and identified linkages between the growth axis and the immune system. Although significant advances have been made with regard to elucidation of various bidirectional communication pathways between the immune system and growth axis in humans and rodents, the current paper focuses on the relationships between the immune system and somatotropic axis in sheep, cattle, and swine. Aspects from historical and current research associated with changes in somatotropic function following immune challenges with endotoxin, parasites, viruses, and bacteria have been provided. Collectively, these studies demonstrate that a bidirectional communication network, similar to that described in humans and rodents, also exists in a variety of domestic livestock. Identifying and understanding this bidirectional communication network could have significant economic benefits if it leads to intervention strategies to prevent production losses associated with sickness and disease.

Seroprevalence of Sarcosystis spp. in cattle and buffaloes from the wet and dry zones of Sri Lanka: a preliminary study

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies to Sarcosystis infection in cattle and buffaloes. Crude antigens derived from cystozoites of Sarcosystis cruzi and antibodies from the sera of naturally infected cattle and buffaloes were used. The assay was validated by determination of the specificity, sensitivity and negative and positive predictive values. Using ELISA, a sero-epidemiological survey for sarcosystosis was carried out in cattle (n = 215) and buffaloes (n = 123) from the wet and dry zones of Sri Lanka. The prevalence of infection in cattle was 69.3%. Prevalence of the infection collectively in both cattle and buffaloes in the dry zone was significantly higher (P < 0.001) than that in the wet zone. The number of sero-positive cattle and buffaloes in the dry zone was significantly higher than that in the wet zone (P < 0.05). Buffaloes in the dry and wet zones showed a greater prevalence of infection (P < 0.05) than cattle.

Effect of progressive cachectic parasitism and growth hormone treatment on hepatic 5'-deiodinase activity in calves

Thyroid status is compromised in a variety of acute and chronic infections. Conversion of thyroxine (T(4)) into the metabolically active hormone, triiodothyronine (T(3)), is catalyzed by 5'-deiodinase (5'D) mainly in extrathyroidal tissues. The objective of this study was to examine the effect of protozoan parasitic infection (Sarcocystis cruzi) on hepatic 5'D (type I) activity and plasma concentrations of T(3) and T(4) in placebo- or bovine GH (bGH)-injected calves. Holstein bull calves (127.5+/-2.0 kg BW) were assigned to control (C, ad libitum fed), infected (I, 250,000 S. cruzi sporocysts per os, ad libitum fed), and pair-fed (PF, non-infected, fed to intake of I treatment) groups placebo-injected, and three similar groups injected daily with pituitary-derived bGH (USDA-B-1, 0.1mg/kg, i.m.) designated as C(GH), I(GH) and PF(GH). GH injections were initiated on day 20 post-infection (PI), 3-4 days prior to the onset of clinical signs of the acute phase response (APR), and were continued to day 56 PI at which time calves were euthanized for liver collection. Blood samples were collected on day 0, 28, and 55 PI. Alterations in nutritional intake did not affect type I 5'D in liver. Treatment with bGH increased (P<0.05) 5'D activity in C (24.6%) and PF (25.5%) but not in I calves. Compared to PF calves, infection with S. cruzi reduced 5'D activity 25% (P<0.05) and 47.8% (P<0.01) in placebo- and bGH-injected calves, respectively. Neither nutrition nor bGH treatment significantly affected plasma concentrations of T(4) and T(3) on day 28 and 55 PI. However, plasma thyroid hormones were reduced by infection. On day 28 PI, the average plasma concentrations of T(3) and T(4) were reduced in infected calves (I and I(GH)) 36.4% (P<0.01) and 29.4% (P<0.05), respectively, compared to pair-fed calves (PF and PF(GH)). On day 55 PI, plasma T(3) still remained lower (23.7%, P<0.01 versus PF) in infected calves while plasma T(4) returned to control values. The data suggest that parasitic infection in growing calves inhibits both thyroidal secretion and extrathyroidal T(4) to T(3) conversion during the APR. After recovery from the APR, thyroidal secretion returns to normal but basal and bGH-stimulated generation of T(3) in liver remains impaired.

Binding of a monoclonal antibody to sporozoites of Sarcocystis singaporensis enhances escape from the parasitophorous vacuole, which is necessary for intracellular development

Early intracellular development in vitro of the cyst-forming protozoon Sarcocystis singaporensis and the influence of a monoclonal antibody on invasion, intracellular localization, and development of sporozoites were studied. As revealed by immunofluorescence using parasite-specific antibodies which labeled the parasitophorous vacuole membrane (PVM) and by ultrastructural analysis, sporozoites invaded pneumonocytes of the rat via formation of a parasitophorous vacuole (PV). About half of the sporozoites left this compartment within the first 8 h postinfection to enter the host cell cytosol. By semiquantitative analysis of acetyl-histone H4 expression of sporozoites, a marker linked to early gene expression of eukaryotic cells, we show (supported by ultrastructural analysis) that escape from the PV appears to be necessary for early intracellular development. More than 90% of sporozoites located in the cytosol expressed high levels of acetylated histone H4 in the nucleus, whereas only a quarter of the intravacuolar sporozoites exhibited a similar signal. As revealed by ultrastructural analysis, young schizonts all resided in the cytosol. Specific binding of a monoclonal antibody (11D5/H3) to sporozoites before invasion significantly enhanced their escape from the PV, whereas cell invasion itself remained unaffected. The antibody actually increased proliferation of the parasites in vitro, providing a further link between residence in the cytosol and successful intracellular development. Monoclonal antibody 11D5/H3 precipitated a major 58-kDa antigen from oocyst-sporocyst extracts and reacted with the cytoplasm and the surface of sporozoites in immunofluorescence assays. Collectively, the observed antibody-parasite interaction suggests the existence of a signaling event that influences intracellular development of Sarcocystis.

Nutritional modulation of somatotropic axis-cytokine relationships in cattle: a brief review

The objective of this review is to summarize data on the interrelationships that exist between nutrition, the endocrine system and their modulation of plasma tumor necrosis factor-alpha responses to endotoxin in cattle. During stress, intake of nutrients often is compromised and a percentage of available nutrients are diverted away from growth processes to stabilize other physiological processes of a higher survival priority. Management practices that minimize the magnitude and duration of disease stress will aid in speeding the return to homeostatic equilibrium. However, the shift away from growth during stress is almost inevitable as a mechanism to survive. Some degree of control and management of the metabolic cost of disease stress involves understanding the integration of nutritional, endocrine and immune signals by cells and working with the natural homeostatic processes. Endocrine hormones and immune system cytokine signals participate in redirecting nutrient use during disease stress. In an intricate interplay, hormones and cytokines regulate, modify and modulate each other's production and tissue interactions to alter metabolic priorities. Levels of dietary protein and energy intake affect patterns of hormones and cytokines in the blood after endotoxin challenge and further modulate the biological actions of many of these regulatory effectors. In vivo, administration of growth hormone to young calves has significant effects to decrease the many specific physiological responses to endotoxemia. Many aspects of nutrition can attenuate or facilitate this effect.

Use of genomic DNA probes for the diagnosis of acute sarcocystosis in experimentally infected cattle

Two clones of 1.4 and 4.33 kilobase pairs (kbp) DNA inserts, were selected from a Sarcocystis cruzi sporozoite genomic library constructed in bacteriophage lambda gt10. These clones strongly hybridized with sporozoite and merozoite DNA and were evaluated as probes for detection of merozoite DNA in clinical samples. Of five calves in the experiment, four were each orally dosed with approximately 200,000 S. cruzi sporocysts; one calf served as non-infected control. Subsequently, blood was collected from the calves twice weekly for 3.5 months and fractionated into buffy coats, polymorphonuclear cells, and plasma. Total cellular DNA extracted from these fractions was dot blotted on nylon membranes and hybridized with the probes radiolabeled with [alpha-32P]dATP. The probes detected merozoites on Day 22 post infection in the buffy coats and intermittently from Day 25-39 in the granulocyte fraction. Parasitemia (i.e. merozoites in blood) was also detected by indirect fluorescent antibody technique (IFAT) and direct microscopy, Diagnosis of sarcocystosis in cattle using genomic DNA probes by dot blot hybridization provides an alternative method of detecting parasitemia that is more rigorous than the other two tests (IFAT, direct microscopy) which rely on morphology of the merozoite and visualization by the examiner. As probes detected merozoite DNA in the granulocyte fraction, polymorphonuclear cells may be involved in the pathogenesis of S.cruzi; however this hypothesis requires further study.

Current research on Sarcocystis species of domestic animals

The genus Sarcocystis is composed of about 130 species of heteroxenous cyst-forming coccidia with differences in life cycle and pathogenicity. Pathogenic Sarcocystis spp. can cause disease in their intermediate hosts, in particular in ruminants. Research on Sarcocystis infections has been impeded by several facets of the parasites. Intermediate as well as definitive hosts can be parasitized by several different species with similarities in biology and morphology. Antigen preparations derived from pathogenic Sarcocystis spp. are highly cross-reactive with antibodies directed against non-pathogenic species. As a consequence, none of the currently available immunological tests is species-specific and can differentiate between pathogenic and non-pathogenic Sarcocystis spp. Over the last decade, new techniques in immunology, protein chemistry and molecular biology have facilitated more advanced studies on the molecular composition and molecular biology of Sarcocystis spp. in various laboratories. The development of species-specific monoclonal antibodies and analyses of the molecular composition of some life-cycle stages of Sarcocystis spp. of cattle and sheep showed that species-specific proteins and antigens exist in these species, although they are not highly abundant. In addition, comparisons of rRNA genes of different Sarcocystis spp. identified unique sequences in the rRNA of pathogenic Sarcocystis spp. that are suitable targets for species-specific identification. Thus, tools have become available that facilitate the development of methods for species-specific identification and differentiation of Sarcocystis spp. as well as the identification and study of molecules that are associated with pathogenicity of some of these parasites.

Specific amplification of Sarcocystis cruzi DNA using a randomly primed polymerase chain reaction assay

The polymerase chain reaction (PCR) method to randomly amplify polymorphic DNA (RAPD) was used to differentiate between Sarcocystis cruzi DNA and bovine DNA. This assay was also exploited to identify a S. cruzi DNA fragment which may be useful as a probe. Five primers ranging in length from 16 to 20 nucleotides were analyzed for their ability to direct the amplification of either bovine or parasite DNA fragments. Two primers, TGA and TGD, preferentially amplified bovine DNA in a mixture of S. cruzi and bovine DNA. The primers TGB and TGF each directed the amplification of S. cruzi DNA instead of bovine DNA. Assays using TGF and S. cruzi DNA resulted in the production of a unique 0.8 kilobase (kb) DNA fragment. This fragment was not amplified from two other closely related coccidian species, Toxoplasma gondii and Sarcocystis campestris. When the 0.8 kb DNA fragment was purified and used as a DNA probe, it only hybridized with DNA from S. cruzi. The results of this study indicate that this DNA fragment may be developed into a useful DNA probe for S. cruzi, and that the RAPD-PCR method may be successfully exploited for the rapid development of DNA probes for parasites and other organisms.

Acute phase protein response, food intake, liveweight change and lesions following intrathoracic injection of yeast in sheep

Acute phase protein concentrations in blood, food intake and liveweight changes were compared in 10 sheep given intrathoracic injections of yeast and 10 control sheep over a period of 61 days. The yeast injections caused acute pleuritis and limited necrotising lung lesions which progressed to fibrous pleural adhesions and walled-off abscesses. The responses of ceruloplasmin, fibrinogen and haptoglobin were closely correlated (r = 0.87 to 0.91) in the yeast-injected sheep with peaks on days 5 or 7 after treatment (4, 4.6 and over 130 times control, respectively). Albumin concentration fell to a nadir of 89 per cent of control on day 12 after treatment. Depression of food intake was temporally related to the 'positive' acute phase protein responses with a nadir on day 5 after treatment (30 per cent of control). Liveweight showed a pronounced fall to five days after treatment and thereafter remained depressed relative to the controls for most of the experimental period. The data suggest that the 'positive' acute phase proteins may be useful indicators of production losses due to inflammatory diseases in sheep.

Effects of tumour necrosis factor-alpha on growth hormone and interleukin 6 mRNA in ovine pituitary cells

The inflammatory cytokines tumour necrosis factor-alpha (TNF alpha), interleukin 1 (IL-1) and interleukin 6 (IL-6) have been demonstrated to influence pituitary hormone synthesis directly and via the hypothalamus. Furthermore, IL-6 is produced by some anterior pituitary cells suggesting a paracrine/autocrine role for this cytokine. We show that TNF alpha induces dispersed ovine pituitary cells to produce increased levels of growth hormone (GH) and IL-6 mRNA and secreted IL-6 in a dose and time dependent manner. TNF alpha at concentrations between 1-1000 U/ml increased GH and IL-6 mRNA, relative to control levels, by 5 h post-stimulation. For IL-6, TNF alpha increased specific mRNA at 5 h and 12 h but not 24 h post-stimulation. TNF alpha also induced secreted IL-6 to levels above that spontaneously secreted at all time points from 5 h to 48 h. Levels of common glycoprotein alpha-subunit and follicle stimulating hormone-beta (FSH beta) subunit mRNA were unaffected by TNF alpha. We conclude that TNF alpha can regulate both GH and IL-6 synthesis in dispersed ovine pituitary cells. The implications for paracrine/autocrine control of pituitary hormone synthesis in acute and chronic disease are discussed.