Advances in understanding the genetic architecture of antibody response to paratuberculosis in sheep by heritability estimate and LDLA mapping analyses and investigation of candidate regions using sequence-based data.

BACKGROUND: Paratuberculosis is a contagious and incurable disease that is caused by Mycobacterium avium subsp. paratuberculosis (MAP) with significant negative effects on animal welfare and farm profitability. Based on a large naturally infected flock over 12 years, we analyzed repeated enzyme-linked immunosorbent assay tests (ELISA), OvineSNP50 BeadChip genotypes and whole-genome sequences imputed from 56 influential animals. The main goals were to estimate the genetic parameters of proxy traits for resistance to MAP, identify genomic regions associated with the host's immune response against MAP and search for candidate genes and causative mutations through association and functional annotation analyses of polymorphisms identified by sequencing. RESULTS: Two variables were derived from ELISA tests. The first, a binary variable, assessed the infection status of each animal over the entire productive life, while the second considered the level of antibody recorded over time. Very similar results were obtained for both variables. Heritability estimates of about 0.20 were found and a significant region capturing 18% and 13% of the genetic variance was detected on ovine chromosome 20 by linkage disequilibrium and linkage analysis on OvineSNP50 positions. Functional annotation and association analyses on the imputed sequence polymorphisms that were identified in this region were carried out. No significant variants showed a functional effect on the genes that mapped to this region, most of which belong to the major histocompatibility complex class II (MHC II). However, the conditional analysis led to the identification of two significant polymorphisms that can explain the genetic variance associated with the investigated genomic region. CONCLUSIONS: Our results confirm the involvement of the host's genetics in susceptibility to MAP in sheep and suggest that selective breeding may be an option to limit the infection. The estimated heritability is moderate with a relevant portion being due to a highly significant region on ovine chromosome 20. The results of the combined use of sequence-based data and functional analyses suggest several genes belonging to the MHC II as the most likely candidates, although no mutations in their coding regions showed a significant association. Nevertheless, information from genotypes of two highly significant polymorphisms in the region can enhance the efficiency of selective breeding programs.

Atypical outbreak of acute coenurosis by Taenia multiceps in a sheep flock.

Herein, we examined the brain of adult ewes and lambs less than 30 days old which were found affected by neurological signs in a flock located in Sardinia (Italy). Gross anatomo-pathological examination of all brains of the animals revealed multiple linear reddish-yellow foci of necrotic purulent inflammation due to oncosphere migration. Histologically, we confirmed a multifocal pyo-granulomatous meningo-encephalitis both in ewes and in lambs, confirming acute coenurosis. Morphological examination and DNA sequencing identified the Taenia multiceps we isolated as Tm1 strain. This report describes for the first time a natural acute coenurosis infection in suckling lambs under 30 days of age.

Whole-Genome Sequencing of Two Canine Herpesvirus 1 (CaHV-1) Isolates and Clinicopathological Outcomes of Infection in French Bulldog Puppies.

Canine herpesvirus 1 (CaHV-1) infects dogs, causing neonatal death and ocular, neurological, respiratory, and reproductive problems in adults. Although CaHV-1 is widespread in canine populations, only four studies have focused on the CaHV-1 whole genome. In such context, two CaHV-1 strains from both the kidney and spleen of 20-day-old deceased French Bulldog puppies were recently isolated in Sardinia, Italy. The extracted viral DNA underwent whole-genome sequencing using the Illumina MiSeq platform. The Italian CaHV-1 genomes were nearly identical (>99%), shared the same tree branch, and clustered near the ELAL-1 (MW353125) and BTU-1 (KX828242) strains, enlarging the completely separated clade discussed by Lewin et al., in 2020. This study aims to provide new insights on the evolution of the CaHV-1, based on high-resolution whole-genome phylogenetic analysis, and on its clinicopathological characterization during a fatal outbreak in puppies.

Sheep with scrapie and mastitis transmit infectious prions through the milk.

Prions are misfolded proteins that are infectious and naturally transmitted, causing a fatal neurological disease in humans and animals. Prion shedding routes have been shown to be modified by inflammation in excretory organs, such as the kidney. Here, we show that sheep with scrapie and lentiviral mastitis secrete prions into the milk and infect nearly 90% of naïve suckling lambs. Thus, lentiviruses may enhance prion transmission, conceivably sustaining prion infections in flocks for generations. This study also indicates a risk of prion spread to sheep and potentially to other animals through dietary exposure to pooled sheep milk or milk products.

Malignant Catarrhal Fever in Sardinia (Italy): A Case Report.

Using a multidisciplinary approach, this report describes a clinical case of malignant catarrhal fever (MCF) occurring in a calf, which shared the pasture with sheep on a farm located in the island of Sardinia (Italy). We confirmed the conventional clinico-histopathological features of MCF, as well was the presence of Ovine herpesvirus type 2 (OvHV-2) DNA in several tissues, employing histological and virological investigations. The phylogenetic analysis revealed that this Sardinian OvHV-2 strain is genetically similar to all the other Italian strains. By Real Time PCR examinations of blood samples collected across Sardinia's sheep population, which is considered the most important reservoir species, we discovered an OvHV-2 prevalence ranging from 20 to 30 percent. Despite the high prevalence of OvHV-2 in the Sardinian sheep population, clinical disease in bovine remains sporadic; further investigations are needed to understand the risk factors that regulate this epidemiological aspect.

The Italian Network of Laboratories for Veterinary Oncology (NILOV) 2.0: Improving Knowledge on Canine Tumours.

Advances in tumour research are crucial, and comparative oncology can improve the knowledge in several ways. Dogs are not only models of specific naturally occurring tumours but can also be sentinels of environmental exposures to carcinogens, as they share the same environment with their owners. The purpose of this work was to describe the data collected by The Italian Network of Laboratories for Veterinary Oncology in the first 9 years of activity (2013-2021) and to evaluate their potential epidemiological significance. Frequencies of tumour topographies and main morphologies in dogs were described, analysed and compared, calculating age-adjusted proportional morbidity ratios and considering several risk factors (breed, sex, period and region of residence). These observations allowed us to highlight differences not only in morphology and topography of some tumours but also to formulate hypotheses on the potential role of some risk factors, e.g., neutering/spaying or geographical location. In our opinion, the results of this case series confirm the importance of initiating and consolidating animal cancer registration initiatives that would facilitate the possibility of conducting multicentric collaborative studies to deepen the knowledge of the epidemiology of tumours in dogs from a comparative perspective.

Association of N176K and L141F dimorphisms of the PRNP gene with lack of pathological prion protein deposition in placentas of naturally and experimentally scrapie-affected ARQ/ARQ sheep.

The placenta is important in the horizontal transmission of the aetiological agent in scrapie-affected sheep. It has been demonstrated that the placentas of fetuses carrying the dimorphism Q171R of the PRNP gene is resistant to pathological prion protein (PrP(Sc)) accumulation in the placenta. To test whether other PRNP polymorphisms are associated with a lack of placental PrP(Sc) deposition, we carried out a study on 26 naturally and 11 experimentally scrapie-affected ewes with or without clinical signs. PrP(Sc) was detected in the placenta of ARQ/ARQ(wild type) fetuses by Western blot and immunohistochemical analysis, but not in ARQN(176)/ARQK(176) or, as expected, ARQ/ARR samples. Furthermore, three of four AL(141)RQ/AF(141)RQ placentas were also PrP(Sc) negative, suggesting that the dimorphism at codon 141 may also mediate placental deposition of PrP(Sc). This finding demonstrates for the first time that fetal PRNP polymorphisms, other than those at codon 171, are associated with the lack of placental deposition of PrP(Sc).

Bayesian Analysis of Three Methods for Diagnosis of Cystic Echinococcosis in Sheep.

Diagnosis of cystic echinococcosis (CE) in sheep is essentially based on necropsy findings. Clinical symptoms can be easily overlooked, while the use of immunological tests is still not recommended for an intra vitam diagnosis. This study assessed the performances of three post-mortem laboratory methods in the diagnosis of ovine CE. In the absence of a single and accurate test as a gold standard, the results of multiple analytical tests can be combined to estimate diagnostic performance based on a Bayesian statistical approach. For this purpose, livers (n = 77), and lungs (n = 79) were sampled from adult sheep and examined using gross pathology, histopathology and molecular analyses. Data from the three diagnostic methods were analyzed using a Bayesian latent class analysis model to evaluate their diagnostic accuracy in terms of sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV). The gross pathology examination revealed excellent diagnostic capabilities in diagnosing ovine CE with an Se of 99.7 (96.7-99.8), Sp of 97.5 (90.3-99.8), PPV of 97.6 (90.5-100), and NPV of 99.7 (96.5-100). The experimental design used in this work could be implemented as a validation protocol in a quality assurance system.

Pathological findings in a Dachshund-cross dog with neuroaxonal dystrophy.

BACKGROUND: Neuroaxonal dystrophy (NAD) is a neurodegenerative condition affecting humans and animals characterized by the widespread presence of swollen axons (spheroids). CASE PRESENTATION: Herein, we report the pathological findings in a case of neuroaxonal dystrophy in a Dachshund-cross puppy, which was euthanized because of a proprioceptive positioning deficits and irreversible ataxia of the hind limbs. Histologically, there was a bilaterally symmetric neuroaxonal dystrophy with eosinophilic axonal spheroids exclusively localized at the level of the ventral posterior lateral nucleus of the thalamus, medial lemniscus, gracilis nucleus, medial cuneatus nucleus in the brain as well as the gracilis and cuneatus fasciculi throughout the spinal cord. CONCLUSION: To the authors' knowledge, this is the first report of canine neuroaxonal dystrophy with this exclusive and specific localization only in the neuronal circuit implicated in the transmission of conscious proprioceptive information.

Glioblastoma with oligodendroglioma component in a ewe.

Herein we describe a glioblastoma partially occupying the telencephalic portion of the left cerebral hemisphere of a Sardinian (syn. Sarda) breed ewe. Microscopically, the mass consisted of a pleomorphic spindle-shaped cell component organized as bundles and numerous small areas of round cells displaying an oligodendroglioma-like aspect. A high number of mitotic figures, large areas of necrosis surrounded by pseudopalisading glial cells, and multiple foci of dystrophic mineralization were also observed. The neoplasm was highly vascularized with glomerular vascular proliferation. Immunohistochemically, neoplastic cells proved to be strongly positive for nestin, vimentin, and olig-2, whereas they were invariably negative for synaptophysin. Few neoplastic cells and reactive astrocytes, mainly located at the edge of necrotic foci, proved to be positive for glial fibrillary acidic protein, whereas glomerular vascular proliferation was clearly positive for factor VIII and vascular endothelial growth factor. Gene sequencing analysis demonstrated homozygous p53 tumor suppressor gene (TP53) point mutations in the DNA-binding domain located in exon 8. The presence of round cells immunoreactive for olig-2 demonstrated that this tumor is a glioblastoma with oligodendroglioma component. Our pathologic, immunohistochemical, and molecular findings largely overlap those previously reported in humans and dogs.

Genetic and pathological characteristics of Cryptococcus gattii and Cryptococcus neoformans var. neoformans from meningoencephalitis in autochthonous goats and mouflons, Sardinia, Italy.

In this study, we examined in Sardinia the brain of 555 autochthonous sheep, 50 goats, and 4 mouflons which were found affected by neurological signs. We found 6 goats and one mouflon with meningoencephalitis caused by Cryptococcus sp. There was no evidence of cryptococcal infections in any of the examined sheep. MLST genotyping on Cryptococcus sp. isolates identified Cryptococcus gatti genotype AFLP4/VGI and Cryptococcus neoformans var. neoformans genotype AFLP2/VNIV. Phylogenetically, all Cryptococcus gattii isolates fell within the autochthonous animal, human and environmental Mediterranean isolate cluster, forming a distinct branch along with environmental strains from Alicante, in the southern Mediterranean coast of Spain.

A lympho-follicular microenvironment is required for pathological prion protein deposition in chronically inflamed tissues from scrapie-affected sheep.

In sheep scrapie, pathological prion protein (PrP(Sc)) deposition occurs in the lymphoreticular and central nervous systems. We investigated PrP(Sc) distribution in scrapie-affected sheep showing simultaneous evidence of chronic lymphofollicular, lymphoproliferative/non-lymphofollicular, and/or granulomatous inflammations in their mammary gland, lung, and ileum. To do this, PrP(Sc) detection was carried out via immunohistochemistry and Western Blotting techniques, as well as through inflammatory cell immunophenotyping. Expression studies of gene coding for biological factors modulating the host's inflammatory response were also carried out. We demonstrated that ectopic PrP(Sc) deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells. On the contrary, no PrP(Sc) deposition was detected in granulomas, even when they were closely located to newly formed lymphoid follicles. A significantly more consistent expression of lymphotoxin α and ß mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and ß signaling new lymphoid follicles' formation and, likely, the occurrence of ectopic PrP(Sc) deposition inside them. Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent's replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.

Enteroglial and neuronal involvement without apparent neuron loss in ileal enteric nervous system plexuses from scrapie-affected sheep.

The enteric nervous system (ENS) probably plays a dominant role in sheep scrapie pathogenesis, but little is known about the cell types involved. We investigated the ileal myenteric and submucosal plexuses of four naturally and four orally experimentally scrapie-affected ARQ/ARQ Sarda sheep, as well as those of 12 healthy-control Sarda sheep carrying different PrP genotypes. All scrapie-affected animals, euthanized at clinical-disease end stage, showed PrPd deposition within enteric glial cells (EGCs) and calbindin-immunoreactive (CALB-IR) and neuronal nitric oxide synthase (nNOS)-IR neurons. Whole-mount investigations revealed no significant differences between the densities of total, CALB-IR and nNOS-IR neurons in scrapie-affected versus healthy sheep, irrespective of PrP genotype. Our results suggest that EGCs and CALB-IR and nNOS-IR neurons are probably involved in the pathogenesis of natural and oral experimental sheep scrapie. Furthermore, the infectious agent may be less pathogenic towards ENS neurons than it is towards central nervous system neurons.