Histidine at codon 154 of the prion protein gene is a risk factor for Nor98 scrapie in goats

Prion protein gene (PRNP) polymorphisms are involved in modulating the appearance of atypical/Nor98 scrapie in sheep, with the alleles AHQ and AF141RQ strongly associated with occurrence of the disease. The presence of histidine at codon 154 has also been detected in Nor98-affected goats, but statistical analysis of the association between Nor98 and goat PRNP polymorphisms has not been reported previously. Here, a case-control study was carried out on eight Nor98-positive goats and 246 negative herdmates belonging to eight Italian Nor98 scrapie outbreaks. The results revealed that histidine at codon 154 is also strongly associated with the disease in goats.

Genetic variability of the PRNP gene in goat breeds from Northern and Southern Italy

AIMS

To determine the variability of the prion protein gene (PRNP) in goats from Northern and Southern Italy.

METHODS AND RESULTS

Genomic DNA isolated from goat blood was polymerase chain reaction (PCR)-amplified for the coding region of the PRNP gene and then sequenced. In total, 13 polymorphic sites were identified: G37V, T110P, G127S, M137I, I142M, I142T, H143R, R154H, P168Q, T194P, R211Q, Q222K and S240P (substitutions I142T and T194P are novel) giving rise to 14 haplotypes. Clear frequency differences between Northern and Southern breeds were found and confirmed by genetic distance analysis.

CONCLUSIONS

Differences in allele distribution were found between Northern and Southern goats, in particular regarding the M142 and K222 alleles, possibly associated to scrapie resistance; philogeographical analysis supported the idea that Northern and Southern breeds may be considered as separate clusters.

SIGNIFICANCE AND IMPACT OF THE STUDY

In Italy only limited studies have been carried out on caprine PRNP genotype distribution; this study is important to fill this lack of information. Moreover the finding of significant differences among allele distributions in Northern and Southern goats, especially if involved in modulating resistance/susceptibility, need to be carefully considered for the feasibility of selection plans for resistance to scrapie.

Evaluation of internal reference genes for quantitative expression analysis by real-time PCR in ovine whole blood

The use of reference genes is commonly accepted as the most reliable approach to normalize qRT-PCR and to reduce possible errors in the quantification of gene expression. The most suitable reference genes in sheep have been identified for a restricted range of tissues, but no specific data on whole blood are available. The aim of this study was to identify a set of reference genes for normalizing qRT-PCR from ovine whole blood. We designed 11 PCR assays for commonly employed reference genes belonging to various functional classes and then determined their expression stability in whole blood samples from control and disease-stressed sheep. SDHA and YWHAZ were considered the most suitable internal controls as they were stably expressed regardless of disease status according to both geNorm and NormFinder software; furthermore, geNorm indicated SDHA/HPRT, YWHAZ/GAPDH and SDHA/YWHAZ as the best reference gene combinations in control, disease-stressed and combined sheep groups, respectively. Our study provides a validated panel of optimal control genes which may be useful for the identification of genes differentially expressed by qRT-PCR in a readily accessible tissue, with potential for discovering new physiological and disease markers and as a tool to improve production traits (e.g., by identifying expression Quantitative Trait Loci). An additional outcome of the study is a set of intron-spanning primer sequences suitable for gene expression experiments employing SYBR Green chemistry on other ovine tissues and cells.

Is HCRTR2 a genetic risk factor for Alzheimer's disease?

BACKGROUNDS/AIMS

Alzheimer's disease (AD) is one of the main types of dementia affecting about 50-55% of all demented patients. Sleep disturbances in AD patients are associated with the severity of dementia and are often the primary reason for institutionalization. These sleep problems partly resemble the core symptoms of narcolepsy, a sleep disorder caused by a general loss of the neurotransmitter hypocretin. The aim of our study was to investigate whether genetic variants in the hypocretin (HCRT) and in the hypocretin receptors 1 and 2 (HCRTR1, HCRTR2) genes could modify the occurrence and the clinical features of AD and to examine if these possible variants influence the role of the protein in sleep regulation.

METHODS

Using a case-control strategy, we genotyped 388 AD patients and 272 controls for 10 SNPs in the HCRT, HCRTR1 and HCRTR2 genes. In order to evaluate which residues belong to the HCRTR2 binding site, we built a molecular model.

RESULTS

The genotypic and allelic frequencies of the rs2653349 polymorphism were different (χ(2) = 5.77, p = 0.016; χ(2) = 6.728, p = 0.035) between AD patients and controls. The carriage of the G allele was associated with an increased AD risk (OR 2.53; 95% CI 1.10-5.80). No significant differences were found in the distribution of either genotypic or allelic frequencies between cases and controls in the HCRTR1 polymorphisms rs2271933, rs10914456 and rs4949449 and in the HCRTR2 polymorphism rs3122156.

CONCLUSION

Our data support the hypothesis that the HCRTR2 gene is likely to be a risk factor for AD. The increased risk inferred is quite small, but in the context of a multi-factorial disease, the presence of this polymorphism may significantly contribute to influencing the susceptibility for AD by interacting with other unknown genetic or environmental factors in sleep regulation.

Identification of single nucleotide polymorphisms in Toll-like receptor candidate genes associated with tuberculosis infection in water buffalo (Bubalus bubalis)

Background

Toll-like receptors play a key role in innate immunity by recognizing pathogens and activating appropriate responses. Pathogens express several signal molecules (pathogen-associated molecular patterns, PAMPs) essential for survival and pathogenicity. Recognition of PAMPs triggers an array of anti-microbial immune responses through the induction of various inflammatory cytokines. The objective of this work was to perform a case-control study to characterize the distribution of polymorphisms in three candidate genes (toll-like receptor 2, toll-like receptor 4, toll-like receptor 9) and to test their role as potential risk factors for tuberculosis infection in water buffalo (Bubalus bubalis).

Results

The case-control study included 184 subjects, 59 of which resulted positive to both intradermal TB test and Mycobacterium bovis isolation (cases) and 125 resulted negative to at least three consecutive intradermal TB tests. The statistical analysis indicated that two polymorphisms exhibited significant differences in allelic frequencies between cases and controls. Indeed, the TT genotype at TLR9 2340 C > T locus resulted significantly associated with susceptibility to bovine tuberculosis (P = 0.030, OR = 3.31, 95% CI = 1.05-10.40). One polymorphism resulted significantly associated with resistance to the disease, and included the CC genotype, at the TLR4 672 A > C locus (P = 0.01, OR = 0.26, 95% CI = 0.08-0.80). Haplotype reconstruction of the TLR2 gene revealed one haplotype (CTTACCAGCGGCCAGTCCC) associated with disease resistance (P = 0.04, OR = 0.51, 95% CI = 0.27–0.96), including the allelic variant associated with disease resistance.

Conclusions

The work describes novel mutations in bubaline TLR2, TLR4 and TLR9 genes and presents their association with M. bovis infection. These results will enhance our ability to determine the risk of developing the disease by improving the knowledge of the immune mechanisms involved in host response to mycobacterial infection, and will allow the creation of multiple layers of disease resistance in herds by selective breeding.

A single nucleotide variant in the promoter region of the CCR5 gene increases susceptibility to arthritis encephalitis virus in goats

Background

The small ruminant lentiviruses (SRLVs) are a heterogeneous group of viruses that includes caprine arthritis encephalitis virus (CAEV) and Maedi-Visna virus (MVV). SRLVs affect the production and welfare of sheep and goats worldwide. There is currently no effective treatment. Their high mutation rate precludes vaccine development, making innovative control measures necessary.

A variant of the chemokine (C-C motif) receptor 5 (CCR5) gene is reportedly involved in resistance to human immunodeficiency (HIV) infection in humans and to SRLV in sheep. The aim of this study was to analyse the genetic structure and variability of the CCR5 gene in goats and to carry out a cross-sectional study to investigate the role of CCR5 genetic variants in controlling susceptibility/resistance to CAEV.

Results

The variant g.1059 T located in the promoter region revealed an interesting association with high proviral loads (a 2.8-fold increased risk). A possible explanation could be an alteration of the transcriptional level. Overexpression of the CCR5 receptor on the cell surface may increase virus internalization and proviral load as a consequence.

Conclusions

Our findings could be advantageously used to reduce the susceptibility of goat herds to CAEV by negatively selecting animals carrying the g.1059 T mutation. Eliminating animals predisposed to high proviral loads could also limit the development of clinical signs and the spread of the virus, since these animals are also highly efficient in shedding the virus.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1979-5) contains supplementary material, which is available to authorized users.

Absence of TARDBP gene mutations in an italian series of patients with frontotemporal lobar degeneration

BACKGROUND/AIM

Recent studies showed that TAR DNA-binding protein 43 (TDP-43), encoded by the TARDBP gene, is a major pathological protein in both sporadic and familial frontotemporal lobar degeneration (FTLD). The aim of this study was to search for mutations of the TARDBP gene in the disease.

METHODS

We sequenced the TARDBP gene in 172 unrelated FTLD patients recruited from 2 Italian memory clinics.

RESULTS

We identified 3 different variants of the TARDBP gene in 12 FTLD patients. Three patients showed a silent variant, Ala66Ala (c.332T --> C) in exon 2. A novel heterozygous mutation was found in intron 4 (c.543 + 51A --> G) in 1 patient, which is not located at the splicing site. Finally, a c.208C --> T variant in the 3' untranslated region was detected in 8 probands. None of the aforementioned variants were predicted to affect TDP-43. Hence, pathogenic mutations were not identified in any of the FTLD cases.

CONCLUSION

Our study, in accord with previous studies in different populations, found no evidence for a major genetic role of the TARDBP gene in FTLD.

Resistant and susceptible rainbow trout (Oncorhynchus mykiss) lines show distinctive immune response to Lactococcus garvieae

Lactococcosis is one of the main bacterial diseases affecting rainbow trout (Oncorhynchus mykiss), with significant economic and sanitary repercussion. Vaccination and antibiotic treatments are commonly used to prevent and control the infection outbreaks; however, these strategies have some drawbacks including limited coverage, handling costs, induction of antibiotic resistance and chemical residues in the environment. Selective breeding programs represent a promising complementary approach for increasing fish disease resistance in commercial farms and some immunological parameters may be tentatively used as indirect indicators for this purpose. The present study investigated for the first time some innate and adaptive immune responses in two groups of rainbow trout derived from selected lines (susceptible and resistant) showing a different "in field" phenotypical resistance to Yersinia ruckeri, Flavobacterium branchiophilum, F. psychrophilum, and Ichthyophthirius multifiliis, after an immersion-dilution based exposure to Lactococcus garvieae carried out in controlled experimental conditions. Twenty-six resistant and twenty-six susceptible female rainbow trout (mean body weight 80 g, 9 months aged, F5 generation) were obtained from an intensive farm considered L. garvieae free and were exposed to the pathogen. Moreover, 10 resistant and 10 susceptible fish were used as uninfected controls. After 5 days, blood and tissue samples were collected for immunological analyses. A significantly higher serum and mucus lysozyme activity was recorded in resistant rainbow trout compared to susceptible fish (P ≤ 0.05), both before and after exposure to L. garvieae. Similarly, respiratory burst activity of head kidney leukocytes resulted more intense in resistant fish (P ≤ 0.05), suggesting that phagocytes could more quickly activate their microbicidal mechanisms to counteract the bacterial spread. Resistant group displayed also an up-regulation of immunoglobulins M (IgM), major histocompatibility complex II (MHC-II) and interleukin 8 (IL-8) gene expression (P ≤ 0.05) and a significantly higher blood lymphocytes count (P ≤ 0.05), highlighting their potential better ability to trigger the recruitment of defensive cells and the initiation of specific immune processes such as antigen presentation to CD4⁺ T lymphocytes and IgM synthesis. The results herein presented might be useful for the identification of immunological markers to be used as indirect indicators in rainbow trout selective breeding programs.

Association of a specific major histocompatibility complex class IIβ single nucleotide polymorphism with resistance to lactococcosis in rainbow trout, Oncorhynchus mykiss (Walbaum)

Major histocompatibility complex (MHC) loci encode glycoproteins that bind to foreign peptides and initiate immune responses through their interaction with T cells. MHC class II molecules are heterodimers consisting of α and β chains encoded by extremely variable genes; variation in exon 2 is responsible for the majority of observed polymorphisms, mostly concentrated in the codons specifying the peptide-binding region. Lactococcus garvieae is the causative agent of lactococcosis, a warm-water bacterial infection pathogenic for cultured freshwater and marine fish. It causes considerable economic losses, limiting the profitability and development of fish industries in general and the intensive production of rainbow trout, Oncorhynchus mykiss (Walbaum), in particular. The disease is currently controlled with vaccines and antibiotics; however, vaccines have short-term efficacy, and increasing concerns regarding antibiotic residues have called for alternative strategies. To explore the involvement of the MHC class II β-1 domain as a candidate gene for resistance to lactococcosis, we exposed 400 rainbow trout to naturally contaminated water. One single nucleotide polymorphism (SNP) and one haplotype were associated with resistance (P < 0.01). These results are promising for using MHC class IIβ as a molecular marker in breeding rainbow trout resistant to lactococcosis.

Evaluation of a molecular method for hepatitis E virus (HEV) detection in pancreatin of porcine origin

Pancreatin is a combination of enzymes, principally amylase, lipase, and protease, used in the treatment of pancreatic endocrine insufficiency in humans. Pancreatin manufactured from imported porcine pancreas carries the risk of hepatitis E virus (HEV) contamination. About 1 % of the starting material for pancreatin manufacture is invariably constituted of the small intestine, which is known to be a major extrahepatic site of HEV replication in pigs. The aim of this study was to evaluate a method to detect and quantify HEV in pancreatin of porcine origin. Because HEV cannot be easily grown by conventional cell culture, an approach based on an established quantitative RT-PCR (RT-qPCR) was selected. This entailed the use of a non-HEV internal control to monitor RNA extraction efficacy and the production of HEV synthetic RNA as a reference to account for the efficacy of reverse-transcription. The method was evaluated by experiments in which HEV (from naturally infected pigs) was spiked in both the starting material (i.e., porcine pancreas homogenate for industrial production) and in the pancreatin itself. A laboratory protocol matching the industrial production workflow was set up and RT-qPCR experiments were carried out to evaluate the method's ability to detect HEV in pancreatin made from HEV-contaminated porcine tissues. The results showed that the method may be employed in two different strategies: to test the porcine pancreas homogenate (quantitative performance) or directly on pancreatin (qualitative assay). While the risk of HEV contamination in pancreatin may be low, it cannot be completely ruled out. Testing for HEV based on the precautionary principle ought to be the guiding rule.

Herpesvirus surveillance in stranded striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) from Italy with emphasis on neuropathological characterization

Herpesvirus (HV) is widely distributed among cetacean populations, with the highest prevalence reported in the Mediterranean Sea. In this study, a comprehensive analysis was conducted, including epidemiological, phylogenetic, and pathological aspects, with particular emphasis on neuropathology, to better understand the impact of HV in these animals. Our results show a higher presence of HV in males compared to females, with males exhibiting a greater number of positive tissues. Additionally, adults were more frequently affected by HV infection than juveniles, with no infections detected in calves or neonates. The affected species were striped (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus). The highest positivity rates were observed in the genital system, cerebrum, and skin tissues. Phylogenetic analysis indicated a higher occurrence of Gammaherpesvirus (GHV) sequences but increased genetic diversity within Alphaherpesvirus (AHV). Key neuropathological features included astro-microgliosis (n = 4) and meningitis with minimal to mild perivascular cuffing (n = 2). The presence of concurrent infections with other pathogens, particularly cetacean morbillivirus (CeMV), underscores the complex nature of infectious diseases in cetaceans. However, the presence of lesions at the Central Nervous System (CNS) with molecular positivity for GHV, excluding the involvement of other potential neurotropic agents, would confirm the potential of this HV subfamily to induce neurological damage. Pathological examination identified lesions in other organs that could potentially be associated with HV, characterized by lymphoid depletion and tissue inflammation. These findings enhance our understanding of HV in odontocetes and highlight the need for ongoing research into the factors driving these infections and their broader implications.