Naturally-infected Sheep Research Articles

Distinctive Toll-like Receptors Gene Expression and Glial Response in Different Brain Regions of Natural Scrapie.

Prion diseases are chronic and fatal neurodegenerative diseases characterized by the accumulation of disease-specific prion protein (PrPSc), spongiform changes, neuronal loss, and gliosis. Growing evidence shows that the neuroinflammatory response is a key component of prion diseases and contributes to neurodegeneration. Toll-like receptors (TLRs) have been proposed as important mediators of innate immune responses triggered in the central nervous system in other human neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. However, little is known about the role of TLRs in prion diseases, and their involvement in the neuropathology of natural scrapie has not been studied. We assessed the gene expression of ovine TLRs in four anatomically distinct brain regions in natural scrapie-infected sheep and evaluated the possible correlations between gene expression and the pathological hallmarks of prion disease. We observed significant changes in TLR expression in scrapie-infected sheep that correlate with the degree of spongiosis, PrPSc deposition, and gliosis in each of the regions studied. Remarkably, TLR4 was the only gene upregulated in all regions, regardless of the severity of neuropathology. In the hippocampus, we observed milder neuropathology associated with a distinct TLR gene expression profile and the presence of a peculiar microglial morphology, called rod microglia, described here for the first time in the brain of scrapie-infected sheep. The concurrence of these features suggests partial neuroprotection of the hippocampus. Finally, a comparison of the findings in naturallyinfected sheep versus an ovinized mouse model (tg338 mice) revealed distinct patterns of TLRgene expression.

Presence of visna/maedi virus in post-vaccination granulomas in naturally-infected sheep: A new factor for virus spread?

Trabajo presentado en el Joint ESVP and ECVP Congress, celebrado en Cluj-Napoca (Rumania), del 5 al 8 de septiembre de 2018

Inflammatory Lesion Patterns in Target Organs of Visna/Maedi in Sheep and their Significance in the Pathogenesis and Diagnosis of the Infection

Ovine visna/maedi (VM) infection is characterized by the development of chronic inflammatory lesions in different organs, mainly in the lung, mammary gland and central nervous system (CNS), with either histiocytic or lymphocytic pattern predominance being described in the CNS. To help to understand the role of host immune response in the development of these patterns, 50 naturally-infected sheep and eight non-infected sheep from intensive milk-producing flocks were studied. The histological lesion patterns in the three main target organs in each sheep were characterized. Lesion severity was determined, including minimal lesions. A histiocytic pattern was observed in 23 sheep (46%), a lymphocytic inflammatory pattern in 19 sheep (38%) and a mixed inflammatory pattern in eight sheep (16%). Forty animals showed moderate or severe lesions (80%), while 10 had minimal lesions (20%). Moderate or severe lesions affected only one target organ in 20 sheep (50%), two organs in 14 sheep (35%) and all three target organs in six sheep (15%). Infection was confirmed by immunohistochemistry (IHC) using an antibody specific for p28 of VM virus/caprine arthritis and encephalitis virus and by polymerase chain reaction (PCR) in all sheep. Minimal inflammatory lesions associated with positive IHC and PCR were observed. The results suggest that the development of a predominant inflammatory pattern in different organs within the same animal may be related to the host immune response. Minimal and focal lesions, not considered previously, should be taken into account when formulating a differential diagnosis in affected sheep.

Toxoplasma gondii in the Cornigliese sheep breed in Italy: Meat juice serology, in vitro isolation and genotyping

Toxoplasma gondii is considered one of the most important food-borne parasitic zoonoses globally and sheep are important intermediate hosts of the parasite. Meat and milk from infected sheep are considered an important source of infection for humans. Here, the authors evaluated T. gondii infection in the Italian Cornigliese sheep breed using meat juice ELISA, and in vitro assay for followed by Real Time-PCR and PCR-RFLP.Twenty-one hearts were collected at slaughter. Meat juice serology was carried out on all samples, while eleven hearts with the highest antibody titres were subjected to acid-peptic digestion and seeding onto Vero cells. DNA was extracted at three different time points following seeding. PCR-positive samples were then genotyped by PCR-RFLP. All the meat juice samples were positive for IgG antibodies against p30 protein of T. gondii. Five of the 11 samples, seeded onto Vero cells, were positive in PCR made on DNA extracted after 21days of culture and the PCR-RFLP revealed a Type-II or Type II variant profile at 9/10 loci. Two out of five samples showed an increase in terms of parasite growth by comparing the Cq values at three different time points. To the authors’ knowledge, this is the first report of in vitro cultivation of T. gondii from muscle tissue of naturally-infected sheep. In vitro assays may be a promising alternative to bioassays and further studies are necessary in order to improve assay performance and to identify possible early markers of parasite proliferation.

Method and system for forming plug and play oxide catalysts

Toxoplasma gondii is considered one of the most important food-borne parasitic zoonoses globally and sheep are important intermediate hosts of the parasite. Meat and milk from infected sheep are considered an important source of infection for humans. Here, the authors evaluated T. gondii infection in the Italian Cornigliese sheep breed using meat juice ELISA, and in vitro assay for followed by Real Time-PCR and PCR-RFLP.Twenty-one hearts were collected at slaughter. Meat juice serology was carried out on all samples, while eleven hearts with the highest antibody titres were subjected to acid-peptic digestion and seeding onto Vero cells. DNA was extracted at three different time points following seeding. PCR-positive samples were then genotyped by PCR-RFLP. All the meat juice samples were positive for IgG antibodies against p30 protein of T. gondii. Five of the 11 samples, seeded onto Vero cells, were positive in PCR made on DNA extracted after 21 days of culture and the PCR-RFLP revealed a Type-II or Type II variant profile at 9/10 loci. Two out of five samples showed an increase in terms of parasite growth by comparing the Cq values at three different time points. To the authors’ knowledge, this is the first report of in vitro cultivation of T. gondii from muscle tissue of naturally-infected sheep. In vitro assays may be a promising alternative to bioassays and further studies are necessary in order to improve assay performance and to identify possible early markers of parasite proliferation.

DOE grants to advance fuel cell components, hydrogen storage

Toxoplasma gondii is considered one of the most important food-borne parasitic zoonoses globally and sheep are important intermediate hosts of the parasite. Meat and milk from infected sheep are considered an important source of infection for humans. Here, the authors evaluated T. gondii infection in the Italian Cornigliese sheep breed using meat juice ELISA, and in vitro assay for followed by Real Time-PCR and PCR-RFLP.Twenty-one hearts were collected at slaughter. Meat juice serology was carried out on all samples, while eleven hearts with the highest antibody titres were subjected to acid-peptic digestion and seeding onto Vero cells. DNA was extracted at three different time points following seeding. PCR-positive samples were then genotyped by PCR-RFLP. All the meat juice samples were positive for IgG antibodies against p30 protein of T. gondii. Five of the 11 samples, seeded onto Vero cells, were positive in PCR made on DNA extracted after 21 days of culture and the PCR-RFLP revealed a Type-II or Type II variant profile at 9/10 loci. Two out of five samples showed an increase in terms of parasite growth by comparing the Cq values at three different time points. To the authors’ knowledge, this is the first report of in vitro cultivation of T. gondii from muscle tissue of naturally-infected sheep. In vitro assays may be a promising alternative to bioassays and further studies are necessary in order to improve assay performance and to identify possible early markers of parasite proliferation.

GM and Honda pair up for fuel cells

Toxoplasma gondii is considered one of the most important food-borne parasitic zoonoses globally and sheep are important intermediate hosts of the parasite. Meat and milk from infected sheep are considered an important source of infection for humans. Here, the authors evaluated T. gondii infection in the Italian Cornigliese sheep breed using meat juice ELISA, and in vitro assay for followed by Real Time-PCR and PCR-RFLP.Twenty-one hearts were collected at slaughter. Meat juice serology was carried out on all samples, while eleven hearts with the highest antibody titres were subjected to acid-peptic digestion and seeding onto Vero cells. DNA was extracted at three different time points following seeding. PCR-positive samples were then genotyped by PCR-RFLP. All the meat juice samples were positive for IgG antibodies against p30 protein of T. gondii. Five of the 11 samples, seeded onto Vero cells, were positive in PCR made on DNA extracted after 21 days of culture and the PCR-RFLP revealed a Type-II or Type II variant profile at 9/10 loci. Two out of five samples showed an increase in terms of parasite growth by comparing the Cq values at three different time points. To the authors’ knowledge, this is the first report of in vitro cultivation of T. gondii from muscle tissue of naturally-infected sheep. In vitro assays may be a promising alternative to bioassays and further studies are necessary in order to improve assay performance and to identify possible early markers of parasite proliferation.

CB&I announces CATOFIN technology award for petrochemical plant in China

Toxoplasma gondii is considered one of the most important food-borne parasitic zoonoses globally and sheep are important intermediate hosts of the parasite. Meat and milk from infected sheep are considered an important source of infection for humans. Here, the authors evaluated T. gondii infection in the Italian Cornigliese sheep breed using meat juice ELISA, and in vitro assay for followed by Real Time-PCR and PCR-RFLP.Twenty-one hearts were collected at slaughter. Meat juice serology was carried out on all samples, while eleven hearts with the highest antibody titres were subjected to acid-peptic digestion and seeding onto Vero cells. DNA was extracted at three different time points following seeding. PCR-positive samples were then genotyped by PCR-RFLP. All the meat juice samples were positive for IgG antibodies against p30 protein of T. gondii. Five of the 11 samples, seeded onto Vero cells, were positive in PCR made on DNA extracted after 21 days of culture and the PCR-RFLP revealed a Type-II or Type II variant profile at 9/10 loci. Two out of five samples showed an increase in terms of parasite growth by comparing the Cq values at three different time points. To the authors’ knowledge, this is the first report of in vitro cultivation of T. gondii from muscle tissue of naturally-infected sheep. In vitro assays may be a promising alternative to bioassays and further studies are necessary in order to improve assay performance and to identify possible early markers of parasite proliferation.

Expression of Cytokeratins in Normal Skin and Scabies Lesions of Naturally-Infected Sheep

Expression of Cytokeratins in Normal Skin and Scabies Lesions of Naturally-Infected Sheep

Quantitative analysis of Babesia ovis infection in sheep and ticks

A quantitative PCR, based on the gene encoding Babesia ovis Surface Protein D (BoSPD) was developed and applied to investigate the presence of Babesia ovis (B. ovis) in its principal vector, the tick Rhipicephalus bursa (R. bursa), and in the ovine host. Quantification of B. ovis in experimentally-infected lambs showed a sharp increase in parasitemia 10–11days in blood-inoculated and adult tick-infested lambs, and 24days in a larvae-infested lamb. A gradual decrease of parasitemia was observed in the following months, with parasites detectable 6–12 months post-infection. Examination of the parasite load in adult R. bursa during the post-molting period using the quantitative PCR assay revealed a low parasite load during days 2–7 post-molting, followed by a sharp increase, until day 11, which corresponded to the completion of the pre-feeding period. The assay was then used to detect B. ovis in naturally-infected sheep and ticks. Examination of samples from 8 sheep and 2 goats from infected flocks detected B. ovis in both goats and in 7 out of the 8 sheep. Additionally, B. ovis was detected in 9 tick pools (5 ticks in each pool) and two individual ticks removed from sheep in infected flocks.

Molecular detection of Babesia ovis in sheep and ticks using the gene encoding B. ovis surface protein D (BoSPD)

The gene encoding Babesia ovis surface protein D (BoSPD) was cloned from B. ovis cDNA library. This gene encodes a polypeptide chain of 155 amino acids, including a predicted 22 amino acid signal peptide. Sequence analysis of the BoSPD suggested that it is a surface protein with no known domains. BLAST analysis followed by multiple alignments showed four orthologs from other Apicomplexan species and suggested that BoSPD is specific for B. ovis. BoSPD-based PCR was then developed to specifically detect B. ovis in experimentally-infected sheep and Rhipicephalus bursa ticks, as well as in field samples. The PCR enabled detection of B. ovis at a calculated parasitemia of 0.0016% and was shown to be specific for B. ovis. Moreover, the BoSPD PCR allowed detection of prolonged subclinical infection in experimentally-infected lambs and in dissected organs of experimentally-infected ticks. Finally, the PCR was used to detect parasitemia in blood samples from naturally-infected sheep and in R. bursa ticks collected from sheep in an infected flock. These results suggest that the BoSPD gene sequence can be used as a specific and sensitive marker, allowing detection of subclinical parasitemia in sheep and in ticks. Based on its predicted properties, BoSPD may be considered as a candidate for anti-B. ovis vaccine development or a target for anti-B.ovis treatment.

Vaccination delays maedi-visna lentivirus infection in a naturally-infected sheep flock

BackgroundThe Maedi-Visna (MV) lentivirus causes two slowly progressive eventually fatal diseases of sheep, Maedi, a progressive interstitial pneumonia, and Visna, a progressive demyelinating disease of the central nervous system. Other lentiviruses also cause fatal slow infections in their natural hosts, e.g. the HIV virus in humans. Results of experimental vaccination against any lentivirus where vaccinees are challenged by natural routes, may therefore be of general interest. From 1991–1998 experiments with formalin-inactivated whole Maedi-Visna virus vaccine were carried out in the Department of Microbiology at the University of Iceland. Western Blot tests showed good immune response to all major proteins of the virus. When aluminium hydroxide was added to the vaccine all vaccinees developed neutralizing antibodies to the vaccine strain at titers 1/8 – 1/256. After housing 5 twin pairs, one twin in each pair vaccinated, the other unvaccinated, with infected sheep for 4 years, all the unvaccinated twins became infected, but only 2 of their vaccinated siblings as confirmed by virus cultivation experiments on tissues from their lungs spleens lymph nodes and choroid plexuses.ResultsOne twin in each of 40 female twin pairs, born into a Maedi-Visna-infected sheep flock and kept under natural farming conditions in Cyprus, was vaccinated at birth, 3 weeks and 3 months, with formalin-inactivated whole Maedi-Visna lentivirus vaccine adjuvanted with aluminium hydroxide. 17 mothers of the twins were seronegative, 13 seroconverting and 10 had old infection. Of 17 vaccinees born to seronegative mothers 9 were uninfected at 28 months, but only 2 of their unvaccinated siblings. Of 13 unvaccinated twins born to seroconverting mothers, 12 caught infection during their first 10 weeks, but only 4 of their vaccinated siblings. Vaccination had no effects on 10 vaccinees born to mothers with long-standing Maedi-Visna infections and broad andibody response at birth of their lambs.ConclusionCompared with their unvaccinated siblings, natural infection was delayed in significant number of vaccinated twins born by seronegative and seroconverting mothers and vaccinated at birth, 3 weeks and 3 months with formalin inactivated whole MV vaccine adjuvanted with aluminium hydroxide. Maternal antibodies interfered with vaccination so early in life if the mother had old infection.

The impact of naturally-occurring, trans-placental bluetongue virus serotype-8 infection on reproductive performance in sheep

Infection with bluetongue virus serotype (BTV)-8 occurred in ruminants in 2006 in Central-Western Europe. The trans-placental passage of this virus has been demonstrated in naturally- and experimentally-infected cattle and in experimentally-infected sheep. Trans-placental transmission is potentially important in the 'over-wintering' of this virus and its subsequent impact on reproductive performance. This epidemiological study was carried out on a sheep flock in Belgium that had experienced a severe outbreak of BTV-8 infection, and where the seroprevalence had increased from 1.3% to 88% between January and November 2007. In total, 476 lambs and 26 aborted fetuses from 300 ewes, lambing at four distinct time periods, were investigated between November 2007 and May 2008. The following evidence suggested that BTV-8 infection occurred in utero: (1) positive PCR results from splenic tissue from aborted fetuses (n=4); (2) fetal malformations suggestive of BTV infection (n=10); (3) positive PCR results from red blood cells in-lambs (n=7), and (4) the presence of antibody at birth in viable lambs prior to the intake of colostrum (n=9). The evidence provided by this investigation strongly suggests that trans-placental BTV-8 infection occurs in naturally-infected sheep and the impact of infection on the reproductive performance of such a naïve flock was considerable, with up to 25% of ewes aborting and with flock fertility reduced by 50%. The contribution of in utero-infected lambs to the over-wintering of BTV appears limited.

Ovine Enzootic Abortion (OEA): a comparison of antibody responses in vaccinated and naturally-infected swiss sheep over a two year period

BackgroundPrevention and control of ovine enzootic abortion (OEA) can be achieved by application of a live vaccine. In this study, five sheep flocks with different vaccination and infection status were serologically tested using a competitive enzyme-linked immunosorbent assay (cELISA) specific for Chlamydophila (Cp.) abortus over a two-year time period.ResultsSheep in Flock A with recent OEA history had high antibody values after vaccination similar to Flock C with natural Cp. abortus infections. In contrast, OEA serology negative sheep (Flock E) showed individual animal-specific immunoreactions after vaccination. Antibody levels of vaccinated ewes in Flock B ranged from negative to positive two and three years after vaccination, respectively. Positive antibody values in the negative control Flock D (without OEA or vaccination) are probably due to asymptomatic intestinal infections with Cp. abortus. Excretion of the attenuated strain of Cp. abortus used in the live vaccine through the eye was not observed in vaccinated animals of Flock E.ConclusionThe findings of our study indicate that, using serology, no distinction can be made between vaccinated and naturally infected sheep. As a result, confirmation of a negative OEA status in vaccinated animals by serology cannot be determined.

Maedi-visna virus infection of ovine mammary epithelial cells

The aim of this work was to perform a complete study of maedi-visna virus (MVV) infected mammary glands of naturally-infected sheep, and to determine if cells other than macrophages undergo a productive viral infection in this organ. Fifteen seropositive and two seronegative ewes were selected from MVV-infected flocks on the basis of clinical indurative mastitis and three sheep from an MVV-free flock. Within the mammary gland, MVV-positive cells were located by immunohistochemistry in the stroma and the epithelial alveolar barrier, most likely the ovine mammary epithelial cells (OMEC) of the acini. In situ hybridization confirmed these findings. Ultrastructural studies showed the presence of lentivirus-like particles budding off the cell surface in the alveolar barrier and also free in the acinar lumen. The presence of mammary histopathological lesions and MVV together with clear indications of productive infection (demonstration of a cytopathic effect in OMEC cultures and infection of co-cultures) were observed in the 15 seropositive and one of the seronegative sheep from the infected flock. These findings demonstrate that the OMEC were infected in vivo and probably underwent productive infection when studied ex-vivo. The OMEC of MVV-free sheep, which had subsequently been infected in vitro with MVV, also showed productive infection when challenged in vitro, confirming the replication of MVV in OMEC in vitro. The presence of MVV-infected OMEC in the mammary gland from infected animals, the productive infection in these OMEC and the release of lentiviral particles to the acinar lumen may have relevance in the pathogenesis and transmission of MVV infection.

Characterization of an immuno-dominant antigen in Brucella ovis and evaluation of its use in an enzyme-linked immunosorbent assay

A panel of 45 Brucella ovis serologically positive sera were tested in immunoblots against B. ovis outer membrane proteins Omp31 and Omp25, purified by preparative SDS-gel electrophoresis. Forty-three sera reacted with Omp31, while only 11 reacted with Omp25, suggesting that Omp31 is identical to the previously reported immuno-dominant 29-kDa protein. Attempts to purify Omp31 on a larger scale by using procedures such as ion exchange-, reversed phase-, affinity- and gel filtration chromatography suggested that the outer membrane proteins were aggregated with rough lipopolysaccharide. Only denaturing SDS-gel filtration chromatography was able to separate proteins of about 29 kDa from rough lipopolysaccharide but did not separate Omp31 from Omp25 in B. ovis preparations. When used in an enzyme-linked immunosorbent assay, this 29-kDa protein preparation was less sensitive and less specific than the routinely used heat-extracted B. ovis antigen. A readily available recombinant E. coli, expressing the gene for Omp31 from Brucella melitensis 16 M, was used to extract and enrich recombinant Omp31 by a temperature-dependent Triton X-114-based technique. When this material was used in immunoblots with the 45 sera from B. ovis-infected sheep and with 10 monoclonal antibodies, raised against B. ovis Omp31, major differences in the antibody reactivity between the recombinant B. melitensis Omp31 and the B. ovis Omp31 were found. Such differences were unexpected because of the known structural and immunological relatedness of outer membrane proteins from various Brucella species. These results indicated that the antibody-response in B. ovis naturally-infected sheep against the immuno-dominant Omp31 was directed against epitopes which were only accessible when the protein was aggregated with rough lipopolysaccharides, or which were formed after aggregation but were not present in the recombinant protein.

Treatment of Brucella melitensis infection in sheep and goats with oxytetracycline combined with streptomycin.

Six treatment regimens using oxytetracycline (OTC) combined with streptomycin (ST) were evaluated for eliminating Brucella melitensis from 480 naturally-infected sheep and goats. Cessation of shedding Brucella from udder secretions and absence of Brucella in selected tissues at autopsy were considered criteria for successful treatment. Four regimens were equally effective in eliminating Brucella in the treated groups of sheep and goats regardless of the source of antibiotics used. These were regimen A (OTC 20 mg/kg intravenously daily for 6 weeks, combined with ST 20 mg/kg intramuscularly [i.m.] daily for 3 weeks), regimen B (long-acting [LA]-OTC 20 mg/kg i.m. every 3 days for 6 weeks, with ST 20 mg/kg i.m. every 3 days for 3 weeks), regimens D and E (LA-OTC 28 mg/kg i.m. every 3 days for 6 weeks, with ST 20 mg/kg i.m. every 3 days for 3 weeks). However, regimen C (LA-OTC 20 mg/kg i.m. every 3 days for 6 weeks, with ST 20 mg/kg i.m. every 3 days for 3 weeks) eliminated Brucella in only 75 of 80 (94%) sheep and goats. Regimen F (LA-OTC 25 mg/kg i.m. every 2 days for 4 weeks, combined with ST 20 mg/kg i.m. every 2 days for 2 weeks) was the most practical, effective and least expensive regimen for eliminating Brucella in the 80 treated sheep and goats. Brucella melitensis biovar 2 was repeatedly isolated from the mammary secretions of all sheep and goats before treatment. It was also isolated repeatedly from the udder secretions of all non-treated control animals and from selected tissue specimens collected from the controls at necropsy.

The effect on the persistence and pattern of nematode infestation of the transfer of naturally infected sheep from pasture to pens.

Abstract Extract In a number of circumstances, helminthologicalstudies would be considerably facilitatedby the transfer of naturally-infected sheep from pasture to pens to enable them to be maintained without further re-infestation. However, at present few data are available concerning the effects of such a transfer upon the persistence and pattern of an existing infestation following the removal of the animals from the source of infection and the sudden marked change of diet. The present work provides information on this point.