Experimental Infection Of Sheep Research Articles

Antagonism between co-infecting gastrointestinal nematodes: A meta-analysis of experimental infections in Sheep

Gastrointestinal nematodes (GIN) have enormous global impacts in humans, wildlife and grazing livestock. Within grazing livestock, sheep are of particular global importance and the economics and sustainability of sheep production are greatly constrained by GIN infections. Natural infections are composed of co-infections with multiple species, and while some past work suggests species can interact negatively with one another within the same host, there is wide variation in reported patterns. Here, we undertook a systematic literature search and meta-analysis of experimental GIN co-infections of sheep to determine whether these experimental studies support the hypothesis of antagonistic interactions between different co-infecting GIN, and test whether aspects of parasite biology or experimental design influence the observed effects. A systematic search of the literature yielded 4848 studies, within which, we identified 19 experimental sheep studies comparing post-mortem worm counts across two co-infecting GIN species. Meta-analysis of 67 effects obtained from these studies provides strong evidence for interactions between GIN species. There was wide variation in the strength and direction of these interactions, but the global effect was significantly antagonistic. On average, there was a decrease in the number of worms of one species when a co-infecting species was also present, relative to a mono-infection with that species alone. This effect was dependent on the infectious dose and was rapidly lost after anthelmintic treatment, suggesting that live worms are required for the effect to occur. Individual parasite species varied in the extent to which they both exerted, and were subject to, these interspecies interactions, and these differences are more complex than simply co-localisation within the gastrointestinal tract. Antagonistic interactions between co-infecting GIN may feedback into their epidemiology as well as potentially affecting the clinical impacts of infection. Furthermore, the consequences of these interactions may be heightened when clinical interventions affect only one species within the co-infecting network. Whilst it was not possible to identify the causes of variation between GIN species in the impact of co-infection, these findings point to new avenues for epidemiological, clinical and mechanistic research on GIN co-infections.

Molecular characterization of immunoinhibitory factors PD-1/PD-L1 in sheep

Sheep have been used as a large animal experimental model for studying infectious diseases. However, due to a lack of staining antibodies and reagents, immunological studies on sheep have not progressed. The immunoinhibitory receptor programmed death-1 (PD-1) is expressed on T lymphocytes. The interaction of PD-1 with its ligand PD-ligand 1 (PD-L1) delivers inhibitory signals and impairs proliferation, cytokine production, and cytotoxicity of T cells. We previously reported that the PD-1/PD-L1 pathway was closely associated with T-cell exhaustion and disease progression in bovine chronic infections using anti-bovine PD-L1 monoclonal antibodies (mAbs). Furthermore, we found that blocking antibodies against PD-1 and PD-L1 restore T-cell functions and could be used in immunotherapy of cattle. However, the immunological role of the PD-1/PD-L1 pathway in chronic diseases of sheep remains unknown. In this study, we identified cDNA sequences of ovine PD-1 and PD-L1 and examined the cross-activity of anti-bovine PD-L1 mAbs against ovine PD-L1 as well as the expression of PD-L1 in ovine listeriosis. The amino acid sequences of ovine PD-1 and PD-L1 share a high degree of identity and similarity with homologs from ruminants and other mammalian species. Anti-bovine PD-L1 mAb recognized ovine PD-L1 on lymphocytes in the flow cytometric assay. Furthermore, an immunohistochemical staining confirmed the PD-L1 expression on macrophages in the brain lesions of ovine listeriosis. These findings indicated that our anti-PD-L1 mAb would be useful for analyzing the ovine PD-1/PD-L1 pathway. Further research is needed to determine the immunological role of PD-1/PD-L1 in chronic diseases such as BLV infection through experimental infection of sheep.

Experimental infection of sheep at mid-pregnancy with archetypal type II and type III Toxoplasma gondii isolates exhibited different phenotypic traits

Toxoplasma gondii is a major cause of reproductive failure in small ruminants. Genotypic diversity of T. gondii strains has been associated with variations in phenotypic traits in in vitro and murine models. However, whether such diversity could influence the outcome of infection in small ruminants remains mostly unexplored. Here, we investigate the outcome of oral challenge in sheep at mid-pregnancy with 10 sporulated oocysts from three different T. gondii isolates belonging to archetypal II and III and selected according to their genetic and phenotypic variations shown in previous studies. Seventy-three pregnant sheep were divided in four groups: G1 infected with TgShSp1 isolate (type II, ToxoDB#3), G2 with TgShSp16 isolate (type II, ToxoDB#3), G3 with TgShSp24 isolate (type III, ToxoDB#2) and G4 of uninfected control sheep. Two different approaches were carried out within this study: (i) the outcome for the pregnancy after infection (n = 33) and (ii) the lesions and parasite tropism and burden at 14 and 28 days post infection (dpi) (n = 40). The onset of hyperthermia and seroconversion occurred one and two days later, respectively in G1 when compared to G2 and G3. However, sheep that suffered from reproductive failure, either by abortion, foetal dead at the time of euthanasia or stillbirth were similar among infected groups (50%, 40% and 47%, respectively). Histological lesions in placentomes and foetal tissues from euthanized animals from the second approach were only detected at 28 dpi and mainly in G1. At 14 dpi, T. gondii-DNA was only detected in G1 in the 11% of the placentomes. However, at 28 dpi the frequency of detection in placentomes was higher in G1 (96%) than in G2 and G3 (7% and 47%, respectively) besides in foetuses was lower in G2 (20%) than in G1 and G3 (100% and 87%, respectively). Regarding late abortions, stillbirths, and lambs of G1, G2 and G3, the frequency of microscopic lesions was similar between groups (79%, 78% and 67%, respectively) whereas T. gondii-DNA was evidenced in 100%, 55% and 100%, respectively. These recently obtained T. gondii isolates led to similar reproductive losses but intra- and inter-genotype variations in the rise of hyperthermia, dynamics of antibodies, frequency of lesions and parasite detection and distribution. Thus, the different phenotypic traits of the isolates could influence the outcome of the infection and mechanisms responsible for it, and further investigations are warranted.

Renal pathological changes in sheep infected with BTV-1 during early pregnancy

Bluetongue is a vector borne, non-contagious, viral disease of ruminants affecting many species of ruminants including cattle, buffalo, sheep, goats, deer, antelope and camel etc. BTV replication and lesions were reported in tissues and organs including skin, lymph nodes, spleen, bone marrow, liver, heart etc. BTV induced lesions have also been observed in the kidney of sheep that include petechiae, subcapsular haemorrhages, and renal tubular necrosis. However, the effect of BTV-1 in the kidney of pregnant sheep remains elusive as pathogenesis of the BTV varied with the serotype and species of the animals. The goal of the present study was to study BTV-1 induced pathological changes in the kidney and viral RNA quantification in pregnant sheep those experimentally infected during early pregnancy. For this, kidney from the sacrificed animals were collected in 10% neutral buffered formalin and RNA later. The presence of the Viral RNA and viral antigen in the ovine kidney and other organs samples was investigated at different day post infection. Histopathological examination of kidneys revealed hypercellularity of mesangial cells, degeneration of renal tubules, casts and multifocal infiltration of lymphocytes and changes were more pronounced at 15th dpi. None of the kidney tissue from infected sheep revealed the BTV antigen using immunohistochemistry. Thus, we concluded that experimental infection of sheep with BTV during early pregnancy induces pathological changes in the kidneys and also leads to moderate viral load in different organs. Further, BTV serotype 1 is unlikely to contribute directly in the renal pathology of pregnant sheep.

Морфологические изменения в печени овец при экспериментальном мелофагозе и после коррекции

The article shows that experimental infection of sheep with melaphagosis leads to significant structural disorders in the skin and liver. There is local necrosis in the liver. In this case, hepatocytes lose their cytolemma, and the cytoplasm of the cells merges to form a homogeneous mass. Cell nuclei undergo karyopyknosis, chromatin is strongly compacted and is located in small groups in a uniform mass of destroyed hepatocytes. Next to necrotic hepatocytes are hepatocytes with poorly defined cell boundaries. At the same time, hepatocytes lose their orientation, that is, they do not form liver plates. Some of them still retain a pronounced nucleus, the karyolemma. Sometimes changes in the liver cover a vast area and in such areas hepatocytes are at different stages of destruction. In the interlobular connective tissue of the liver, extensive areas with accumulations of lymphoid tissue are revealed. Blood vessels, especially sinusoidal capillaries, are characterized by plethora and perivascular edema. Blood stasis is accompanied by adhesion of leukocytes to endotheliocytes and gradual migration of leukocytes into the perivascular zone. The use of Mediatrin to combat bloodsuckers leads to the elimination of the cause of destruction in the body, but the drug itself has side effects. In sheep, after Mediatrin, destructive processes in hepatocytes remain in the liver, but less swelling and cellular reaction are visible. In the treatment of Mediatrin + Eracondom, clusters of lymphoid cells are still found in the interlobular connective tissue, their number is small, they are mainly concentrated in the area of the liver triad. When Mediatrin + oxymethyluracil (OMU) is added to sheep feed, large foci of necrosis are not detected in the liver. However, individual hepatocytes do not have a clear boundary. In the vast majority of cases, hepatocytes have a cubic or polygonal shape, the nuclei are located in the central zone, the nucleoli are well defined, the chromatin is homogeneous and evenly distributed. Thus, in all experimental groups of sheep, when treated with Mediatrin + Eracond or OMU, a pronounced positive trend in the histological structures of the liver is determined.

Морфологические изменения нервных волокон в коже овец при мелофагозе

Experimental infection of sheep with melaphagosis leads to significant structural damage to the skin and its nerve fibers. Bloodsuckers are mechanically transferred through skin scratching to endothelial cells and tissue settled macrophages from places of microtrauma caused by the piercing- sucking apparatus of the carriers and the runes themselves. Proboscis parasites injure the skin, blood vessels, causing inflammation. A synchrony of local and generalized inflammatory processes is formed, which last for a long time due to the blood-sucking of ectoparasites. Periodic suction of blood is accompanied by injection of saliva and coxal fluid into the capillary, which contain the pathogen, anticoagulants and enzymes. At the site of injury, labrocyte degranulation occurs, a large number of inflammatory mediators are released: histamine, heparin, serotonin, which initiate an inflammatory reaction and pain syndrome. Re-irritation of skin receptors, afferent pathways leads to depletion of metabolites in the nerve fibers, and dystrophic processes develop. The protective reaction at the site of the entrance gate is accompanied by the simultaneous generalization of the recovery process after the treatment of sheep with mediatrin. In the skin, compensatory- adaptive changes are observed in the epithelial sheaths of the hair roots, in the sebaceous glands and the restoration of the structure of the endothelium of the blood capillaries. Significant destructive changes in the structure of collagen and elastic fibers remain in the reticular layer of the dermis. Labrocytes, with a large number of granules, testify to a decrease in the intensity of the inflammatory process in the skin of sheep.

Biological and molecular characterization of a sheep pathogen isolate of Mannheimia haemolytica and leukotoxin production kinetics.

Background and Aim:Mannheimia haemolytica (Mha) is a common agent of pneumonia in ruminants globally, causing economic losses by morbidity, mortality, and treatment costs. Infection by Mha is often associated with or promoted by respiratory viral pathogens and environmental conditions. Infections due to Mha have rarely been described in small ruminants. This study reports the biological and molecular characteristics of a new Moroccan Mha isolate from small ruminants presenting typical respiratory symptoms. We also studied the cultural parameters, growth kinetics, and Lkt excretion of the isolate and its pathogenicity on laboratory animals and small ruminants.Materials and Methods:Suspected pasteurellosis cases in sheep and goat flocks in Morocco were investigated. A local strain of Mha was isolated and identified using biochemical and molecular methods. Polymerase chain reaction-targeting specific genes were used for serotyping and phylogenetic analyses; further, leukotoxin production, cytotoxicity, and pathogenicity of the isolate in mice, goats, and sheep were investigated.Results:Phylogeny analysis revealed 98.76% sequence identity with the USA isolate of 2013; the strain growth with a cycle of 9-10 h with leukotoxin secretion was detected by NETosis and quantified by cytotoxicity and mortality of mice. Goat and sheep infections cause hyperthermia, with characteristic postmortem lesions in the trachea and lung.Conclusion:A local isolate of Mha from sheep that died of pneumonia was characterized for the 1st time in North Africa using biological and molecular methods. Although growth on appropriate culture media is accompanied by intense leukotoxin secretion, experimental infections of sheep and goats cause hyperthermia and typical lesions of pneumonia.

Recognition Pattern of the Fasciola hepatica Excretome/Secretome during the Course of an Experimental Infection in Sheep by 2D Immunoproteomics.

Excretory/secretory products released by helminth parasites have been widely studied for their diagnostic utility, immunomodulatory properties, as well as for their use as vaccines. Due to their location at the host/parasite interface, the characterization of parasite secretions is important to unravel the molecular interactions governing the relationships between helminth parasites and their hosts. In this study, the excretory/secretory products from adult worms of the trematode Fasciola hepatica (FhES) were employed in a combination of two-dimensional electrophoresis, immunoblot and mass spectrometry, to analyze the immune response elicited in sheep during the course of an experimental infection. Ten different immunogenic proteins from FhES recognized by serum samples from infected sheep at 4, 8, and/or 12 weeks post-infection were identified. Among these, different isoforms of cathepsin L and B, peroxiredoxin, calmodulin, or glutathione S-transferase were recognized from the beginning to the end of the experimental infection, suggesting their potential role as immunomodulatory antigens. Furthermore, four FhES proteins (C2H2-type domain-containing protein, ferritin, superoxide dismutase, and globin-3) were identified for the first time as non-immunogenic proteins. These results may help to further understand host/parasite relationships in fasciolosis, and to identify potential diagnostic molecules and drug target candidates of F. hepatica.

Dynamics of the immune response in experimental infection of sheep with the virus of bovine leukemia

Dynamics of the immune response in experimental infection of sheep with the virus of bovine leukemia

Experimental infection of sheep with Bovine leukemia virus (BLV): Minimum dose of BLV-FLK cells and cell-free BLV and neutralization activity of natural antibodies

Bovine leukemia virus (BLV) is an important cattle pathogen that causes major economic losses worldwide, especially in dairy farms. The use of animal models provides valuable insight into the pathogenesis of viral infections. Experimental infections of sheep have been conducted using blood from BLV-infected cattle, infectious BLV molecular clones or tumor-derived cells. The Fetal Lamb Kidney cell line, persistently infected with BLV (FLK-BLV), is one of the most commonly used long-term culture available for the permanent production of virus. FLK-BLV cells or the viral particles obtained from the cell-free culture supernatant could be used as a source of provirus or virus to experimentally infect sheep. In this report, we aimed to determine the minimum amount of FLK-BLV cells or cell-free supernatant containing BLV needed to produce infection in sheep. We also evaluated the amount of antibodies obtained from a naturally-infected cow required to neutralize this infection. We observed that both sheep experimentally inoculated with 5000 FLK-BLV cells became infected, as well as one of the sheep receiving 500 FLK-BLV cells. None of the animals inoculated with 50 FLK-BLV cells showed evidence of infection. The cell-free FLK-BLV supernatant proved to be infective in sheep up to a 1:1000 dilution. Specific BLV antibodies showed neutralizing activity as none of the sheep became infected. Conversely, the animals receiving a BLV-negative serum showed signs of BLV infection. These results contribute to the optimization of a sheep bioassay which could be useful to further characterize BLV infection.

Experimental infection of sheep, goats and cattle with a bluetongue virus serotype 4 field strain from Bulgaria, 2014.

In 2014, a new bluetongue virus serotype 4 (BTV-4) strain was detected in southern Greece and spread rapidly throughout the Balkan Peninsula and adjacent countries. Within half a year, more than 7,068 outbreaks were reported in ruminants, particularly in sheep. However, the reported morbidity and case fatality rates in ruminants varied. The pathogenesis of a Bulgarian BTV-4 strain isolated from sheep during the BTV-4 epizootic was studied in different species. Therefore, four sheep, three goats and three cattle were experimentally infected with the isolate BTV-4/BUL2014/15 and monitored for clinical signs up to several weeks. Serum and whole-blood samples were collected at regular intervals and subjected to serological and virological analyses. In this context, BTV-4-specific real-time RT-PCR assays were developed. The infection kinetics were similar to those known for other traditional BTV serotypes, and only mild BT-like clinical signs were observed in goats and sheep. In cattle, no obvious clinical signs were observed, except a transient increase in body temperature. The study results contrast with the severe clinical signs reported in sheep experimentally infected with an African BTV-4 strain and with the reports of BT-like clinical signs in a considerable proportion of different ruminant species infected with BTV-4 in the Balkan region and Italy. The discrepancies between the results of these animal trials and observations of BTV-4 infection in the field may be explained by the influence of various factors on the manifestation of BT disease, such as animal breed, fitness and virus strain, as described previously.

Pathogenic outcome following experimental infection of sheep with Chlamydia abortus variant strains LLG and POS.

This study investigated the pathogenesis of two variant strains (LLG and POS) of Chlamydia abortus, in comparison to a typical wild-type strain (S26/3) which is known to be responsible for late term abortion in small ruminants. Challenge with the three strains at mid-gestation resulted in similar pregnancy outcomes, with abortion occurring in approximately 50–60% of ewes with the mean gestational lengths also being similar. However, differences were observed in the severity of placental pathology, with infection appearing milder for strain LLG, which was reflected in the lower number of organisms shed in vaginal swabs post-partum and less gross pathology and organisms present in placental smears. Results for strain POS were somewhat different than LLG with a more focal restriction of infection observed. Post-abortion antibody responses revealed prominent differences in seropositivity to the major outer membrane protein (MOMP) present in elementary body (EB) preparations under denaturing conditions, most notably with anti-LLG and anti-POS convalescent sera where there was no or reduced detection of MOMP present in EBs derived from the three strains. These results and additional analysis of whole EB and chlamydial outer membrane complex preparations suggest that there are conformational differences in MOMP for the three strains. Overall, the results suggest that gross placental pathology and clinical outcome is not indicative of bacterial colonization and the severity of infection. The results also highlight potential conformational differences in MOMP epitopes that perhaps impact on disease diagnosis and the development of new vaccines.

Small Ruminant Lentiviruses in Sheep: Pathology and Tropism of 2 Strains Using the Bone Marrow Route.

The objective of this work was to comparatively study the tissue tropism and the associated pathology of 2 autochthonous small ruminant lentivirus (SRLV) field strains using an experimental infection in sheep through the bone marrow. Fifteen male, SRLV-free lambs of the Rasa Aragonesa breed were inoculated with strain 697 (nervous tissue origin, animals A1-A6), with strain 496 (articular origin, animals B1-B6), or with uninfected culture medium (C1-C3). Clinical, serologic, and polymerase chain reaction (PCR) evaluations were performed periodically. Two lambs from each infected group and a control animal were euthanized at 134, 273, and 319 days postinfection. Tissues were analyzed by gross and histopathologic evaluation; immunohistochemistry for CD3, CD4, CD8, CD68, and FoxP3 cell markers; lung morphometric evaluation; and tissue proviral quantification by PCR. All infected animals became positive either by enzyme-linked immunosorbent assay and/or PCR, with group B lambs showing the highest serologic values and more consistently positive PCR reactions. Group A lambs showed representative lung lesions but only mild histopathologic changes in the central nervous system (CNS) or in carpal joints. Contrarily, group B lambs demonstrated intense carpal arthritis and interstitial pneumonia but an absence of lesions in the CNS. Proviral copies in tissues were detected only in group B lambs. Experimental infection with these SRLV strains indicates that strain 496 is more virulent than strain 697 and more prone to induce arthritis, whereas strain 697 is more likely to reproduce encephalitis in Rasa Aragonesa lambs. Host factors as well as viral factors are responsible for the final clinicopathologic picture during SRLV infections.

Experimental Infection of Sheep With Pseudorabies Viruses Isolated In Shanghai, China, Between 2010 and 2012

For many years, pseudorabies has been efficiently controlled in China by vaccination. However, a sudden outbreak occurred on many pig farms during 2012-2013. In this study, phylogenetic analysis was carried out with the aim of understanding the genetic relatedness between strains in both populations and comparing strains in China with those circulating in other countries. To obtain more pathogenetic relevant data regarding two pseudorabies virus (PRV) isolates (SH2010 and SH2012) in sheep, we evaluated samples of PRV isolated in Shanghai, China between 2010 and 2012. Based on clinical signs, body temperature variation, and the maximum amounts of viral DNA in unvaccinated/infected sheep, the emerging PRV variant strain, SH2012 was observed to be more highly virulent than the traditional PRV SH2010 strain. The data of the present study will aid in a better understanding of the differences in pathogenicity between the traditional PRV SH2010 strain and the emerging PRV variant strain SH2012.

An experimental ovine Theileriosis: The effect of Theileria lestoquardi infection on cardiovascular system in sheep

The malignant ovine theileriosis is caused by Theileria lestoquardi, which is highly pathogenic in sheep. Theileriosis involves different organs in ruminants, but the effect of the disease on the cardiovascular system is unclear. To understand the pathogenesis of T. lestoquardi on the cardiovascular system, Baluchi breed sheep were infected with the mentioned parasite by releasing unfed adults of Hyalomma anatolicum anatolicum, which were infected with T. lestoquardi. The infected sheep were clinically examined on days 0, 2, 5, 7, 10, 12, 14, 17, and 21, and the blood samples were collected for biochemical parameters measurement. At termination of the experiment, the infected sheep were euthanized and pathological examinations of heart tissue were conducted. During experimental infection of sheep with T. lestoquardi, activities of cardiac troponin I (cTnI), lactate dehydrogenase, and aspartate aminotransferase, were significantly increased (P˂0.05), while a conspicuous decrease (P˂0.05) was observed in creatine phosphokinase activities. Alterations made in biochemical factors almost coincided with the presence of piroplasm in the blood and schizont in lymph nodes. Maximum and minimum of parasitemia in the sheep stood between 3.3% and 0.28%, respectively. In addition, electrocardiography revealed sinus tachycardia, sinus arrhythmia, sino-atrial block and ST-elevation, atrial premature beat, and alteration in QRS and in T waves’ amplitude. Heart histopathological examination showed hyperemia, infiltration of mononuclear inflammatory cells into interstitial tissue, endocarditis, and focal necrosis of cardiac muscle cells. In addition, in one of the sheep, definite occurrence of infarction was observed. The results indicate that T. lestoquardi infection has devastating pathological impacts on the cardiovascular system of sheep. Furthermore, measurement of the cTnI amount is a useful biochemical factor for diagnosis and for better understanding of the severity and progression of the disease and its effects on cardiac tissue.

Experimental Infection of Sheep at 45 and 60 Days of Gestation with Schmallenberg Virus Readily Led to Placental Colonization without Causing Congenital Malformations.

BackgroundMain impact of Schmallenberg virus (SBV) on livestock consists in reproductive disorders, with teratogenic effects, abortions and stillbirths. SBV pathogenesis and viral placental crossing remain currently poorly understood. Therefore, we implemented an experimental infection of ewes, inoculated with SBV at 45 or 60 days of gestation (dg).Methodology“Mourerous” breed ewes were randomly separated in three groups: eight and nine ewes were subcutaneously inoculated with 1 ml of SBV infectious serum at 45 and 60 dg, respectively (G45 and G60). Six other ewes were inoculated subcutaneously with sterile phosphate buffer saline as control group. All SBV inoculated ewes showed RNAemia consistent with previously published studies, they seroconverted and no clinical sign was reported. Lambs were born at term via caesarian-section, and right after birth they were blood sampled and clinically examined. Then both lambs and ewes were euthanatized and necropsied.Principal Findings/SignificanceNo lambs showed any malformation suggestive of SBV infection and none of them had RNAemia or anti-SBV antibodies prior to colostrum uptake. Positive SBV RNA detection in organs was rare in both G45 and G60 lambs (2/11 and 1/10, respectively). Nevertheless most of the lambs in G45 (9/11) and G60 (9/10) had at least one extraembryonic structure SBV positive by RTqPCR. The number of positive extraembryonic structures was significantly higher in G60 lambs. Time of inoculation (45 or 60 dg) had no impact on the placental colonization success rate but affected the frequency of detecting the virus in the offspring extraembryonic structures by the time of lambing. SBV readily colonized the placenta when ewes were infected at 45 or 60 dg but infection of the fetuses was limited and did not lead to congenital malformations.

Characterization of one sheep border disease virus in China.

BackgroundBorder disease virus (BDV) causes border disease (BD) affecting mainly sheep and goats worldwide. BDV in goat herds suffering diarrhea was recently reported in China, however, infection in sheep was undetermined. Here, BDV infections of sheep herds in Jiangsu, China were screened; a BDV strain was isolated and identified from the sheep flocks in China. The genomic characteristics and pathogenesis of this new isolate were studied.ResultsIn 2012, samples from 160 animals in 5 regions of Jiangsu province of China were screened for the presence of BDV genomic RNA and antibody by RT-PCR and ELISA, respectively. 44.4% of the sera were detected positively, and one slowly grown sheep was analyzed to be pestivirus RNA positive and antibody-negative. The sheep kept virus positive and antibody negative in the next 6 months of whole fattening period, and was defined as persistent infection (PI). The virus was isolated in MDBK cells without cytopathic effect (CPE) and named as JSLS12-01. Near-full-length genome sequenced was 12,227 nucleotides (nt). Phylogenetic analysis based on 5'-UTR and Npro fragments showed that the strain belonged to genotype 3, and shared varied homology with the other 3 BDV strains previously isolated from Chinese goats. The genome sequence of JSLS12-01 also had the highest homology with genotype BDV-3 (the strain Gifhorn). Experimental infections of sheep had mild clinical signs as depression and short-period mild fever (5 days). Viremia was detected in 1–7 days post-infection (dpi), and seroconversion began after 14 dpi.ConclusionsThis study reported the genomic and pathogenesis characterizations of one sheep BDV strain, which confirmed the occurrence of BDV infection in Chinese sheep. This sheep derived BDV strain was classified as BDV-3, together with the goat derived strains in China. These results might be helpful for further understanding of BDV infection in China and useful for prevention and control of BDV infections in the future.

Experimental infection of sheep with ovine and bovine Dichelobacter nodosus isolates

The aim of this study was, under experimental conditions, to investigate infection of Norwegian White sheep with ovine and bovine isolates of Dichelobacter nodosus of varying virulence. In addition, the efficacy of gamithromycin as a treatment for the experimentally induced infections was examined. The study was performed as a single foot inoculation using a boot. Four groups, each with six lambs, were inoculated with four different challenge strains (Group 1: benign bovine strain; Group 2: virulent bovine strain; Group 3: benign ovine strain; Group 4: virulent ovine strain). The main criterion to determine that infection was transferred was that D. nodosus isolate was obtained by culture. After the trial all lambs were treated with gamithromycin. Clinical symptoms of footrot developed in all groups, and when removing the boots two weeks after challenge, D. nodosus was isolated from 5 of 24 experimental lambs. All lambs tested negative for D. nodosus by PCR within six weeks after treatment with gamithromycin. This study strongly indicates that D. nodosus isolates from both sheep and cattle can be transferred to sheep under experimental conditions. The study also indicates that gamithromycin may be effective against D. nodosus.

Experimental infection of sheep and goats with a recent isolate of peste des petits ruminants virus from Kurdistan

Peste des petits ruminants (PPR) is a contagious viral disease of sheep and goats common in Africa and Asia. Its high morbidity and mortality has a devastating impact on agriculture in developing countries. As an example, an Asian lineage IV strain of PPRV was responsible for mass fatalities among wild goats in Kurdistan in 2010/2011.In separate experiments, three sheep and three goats of German domestic breeds were subcutaneously inoculated with the Kurdish virus isolate; three uninfected sheep and goats were housed together with the inoculated animals. All inoculated animals, all in-contact goats and two in-contact sheep developed high fever (up to 41.7°C), depression, severe diarrhea, ocular and nasal discharge as well as ulcerative stomatitis and pharyngitis. Infected animals seroconverted within a few days of the first detection of viral genome. Clinical signs were more pronounced in goats; four out of six goats had to be euthanized. Necropsy revealed characteristic lesions in the alimentary tract. Peste des petits ruminants virus (PPRV) RNA was detected in blood as well as nasal, oral and fecal swabs and tissues.The 2011 Kurdish strain of PPRV is highly virulent in European goats and spreads easily to in-contact animals, while disease severity and contagiosity in sheep are slightly lower. PPRV strains like the tested recent isolate can have a high impact on small ruminants in the European Union, and therefore, both early detection methods and intervention strategies have to be improved and updated regularly.

Peste des Petits Ruminants Virus Tissue Tropism and Pathogenesis in Sheep and Goats following Experimental Infection

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of virus replication. The results presented in this study provide models for the comparative evaluation of PPRV pathogenesis and tissue tropism in both sheep and goats. These models are suitable for the establishment of experimental parameters necessary for the evaluation of vaccines, as well as further studies into PPRV-host interactions.