Characterization of ovine gammaherpesvirus 2 in a goat by nanoplate digital PCR and other diagnostic methods

The Macavirus, ovine gammaherpesvirus 2 (OvGHV2), is the cause of sheep-associated malignant catarrhal fever (SA-MCF). Although SA-MCF occurs in a wide range of mammalian hosts, there are few descriptions of this disease and/or infection in goats. This report describes the findings observed in a goat that was infected by OvGHV2 and adds to the rare description of this infection in this animal species. A 6.5-year-old, female, Anglo Nubian goat, with a neurological syndrome, that was euthanized after severe esophageal obstruction was investigated to determine the cause of the brain disease. Histopathology revealed cerebral cortical edema, hemorrhagic rhombencephalitis, severe hepatic necrosis, and atrophic enteritis. An immunohistochemical (IHC) assay identified intracytoplasmic antigens of a malignant catarrhal fever virus (MCFV) within epithelial cells of the intestine, liver, lungs, and kidneys. A semi-nested PCR assay amplified the partial fragment of the OvGHV2 tegument protein gene from the intestine, confirming that the MCFV identified by IHC was OvGHV2. A qPCR assay that targeted the OvGHV2 polymerase gene revealed an elevated quantification cycle (Cq), while nanoplate-based digital PCR (dPCR) detected low viral copy load within the OvGHV2 DNA. Furthermore, the nucleic acids of several disease pathogens associated with diseases in ruminants were not amplified. However, the exact cause of the neurological syndrome remained obscure since nucleic acids of neurological disease pathogens such as bovine viral diarrhea virus, bovine alphaherpesvirus 1 and 5, Histophilus somni, and OvGHV2 were not detected from the brain. Collectively, the results of the Cq and dPCR confirmed that this goat was infected with a low viral load of OvGHV2, which probably was insufficient to induce the typical histopathological alterations and subsequent clinical manifestations associated with SA-MCF and/or infections by OvGHV2. Therefore, elevated viral loads of OvGHV2 would have been required for the development of histological lesions and/or clinical manifestations of SA-MCF in this goat. Furthermore, the dPCR methodology can be used for the efficient detection and quantification of OvGHV2 DNA in animals with or without clinical and/or histopathological evidence of SA-MCF. Additionally, since previous cases of OvGHV2 infections in goats did not have the typical clinical manifestations of SA-MCF, one wonders if this Macavirus can induce SA-MCF in goats.

The Role of Mycoplasma bovirhinis in the Development of Singular and Concomitant Respiratory Infections in Dairy Calves from Southern Brazil

The role of Mycoplasma bovirhinis in the development of pulmonary disease in cattle is controversial and was never evaluated in cattle from Latin America. This study investigated the respiratory infection dynamics associated with M. bovirhinis in suckling calves from 15 dairy cattle herds in Southern Brazil. Nasal swabs were obtained from asymptomatic (n = 102) and calves with clinical manifestations (n = 103) of bovine respiratory disease (BRD) and used in molecular assays to identify the specific genes of viral and bacterial disease pathogens of BRD. Only M. bovirhinis, bovine coronavirus (BCoV), ovine gammaherpesvirus 2 (OvGHV2), Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica were detected. M. bovirhinis was the most frequently diagnosed pathogen in diseased (57.8%; 59/102) and asymptomatic (55.3%; 57/103) calves at all farms. BCoV-related infections were diagnosed in diseased (52%; 53/102) and asymptomatic (51.4%; 53/103) calves and occurred in 93.3% (14/15) of all farms. Similarly, infectious due to OvGHV2 occurred in diseased (37.2%; 38/102) and asymptomatic (27.2%; /28/103) calves and were diagnosed in 80% (12/15) of all farms investigated. Significant statistical differences were not identified when the two groups of calves were compared at most farms, except for infections due to OvGHV2 that affected five calves at one farm. These results demonstrated that the respiratory infection dynamics of M. bovirhinis identified in Southern Brazil are similar to those observed worldwide, suggesting that there is not enough sufficient collected data to consider M. bovirhinis as a pathogen of respiratory infections in cattle. Additionally, the possible roles of BCoV and OvGHV2 in the development of BRD are discussed.

Association of ovine gammaherpesvirus 2 with an outbreak of acute respiratory disease in dairy cattle

This study investigated the cause of an outbreak of an acute respiratory disease syndrome followed by episodes of diarrhea in a dairy cattle herd from Southern Brazil. Deep nasal swabs (DNS) from asymptomatic calves, calves with pulmonary discomfort, and diarrheic calves after episodes of respiratory distress were used in molecular assays designed to detect the principal pathogens associated with bovine respiratory disease (BRD). Fecal samples were used for the molecular detection of bovine enteric disease agents. Pulmonary tissues from three calves and a cow that died were evaluated by molecular assays to identify 11 agents associated with the development of BRD. The intestinal and pulmonary fragments of one calf and the cow revealed atrophic enteritis and interstitial pneumonia by histopathology, respectively. Immunohistochemistry (IHC) identified intralesional antigens of a malignant catarrhal fever virus, genus Macavirus, within epithelial cells of the lungs and intestines. Molecular assays amplified ovine gammaherpesvirus 2 (OvGHV2) from most of the DNS, and the pulmonary and intestinal fragments from the animals that died, confirming that the Macavirus identified by IHC was OvGHV2. Concomitant pulmonary infections of OvGHV2 with bovine gammaherpesvirus 6 and bovine coronavirus were identified. Additionally, bovine viral diarrhea virus 1b and Aichivirus B were detected in the fecal samples. These findings demonstrated that OvGHV2, a Macavirus, was the disease agent most frequently (81.2%; 13/16) associated with singular pulmonary infections during this outbreak of BRD, suggesting that this virus may be another potential agent of respiratory disease of cattle.

Possible Association of Bovine Gammaherpesvirus 6 with Pulmonary Disease in a Cow

Bovine gammaherpesvirus 6 (BoGHV6), previously known as bovine lymphotropic virus, is a member of the Macavirus genus, subfamily Gammaherpesvirinae. Other members of the genus Macavirus include viruses that produce malignant catarrhal fever (MCF) in mammalian hosts, collectively referred to as the MCF virus (MCFV) complex, and the porcine lymphotropic herpesvirus (PLHV). However, the current role of BoGHV6 in the development of diseases and/or disease syndromes remains uncertain and controversial. This paper investigated the participation of BoGHV6 in the development of pulmonary disease in a cow with interstitial pneumonia by histopathology and molecular testing. Tissue antigens of common viral agents of respiratory diseases and Mycoplasma bovis were not identified by immunohistochemistry. Additionally, molecular assays designed to amplify common bacterial and viral pathogens of pulmonary disease did not amplify the nucleic acids of these agents. However, a pan-PCR assay amplified the DNA of the herpesvirus polymerase gene, while the specific BoGHV6 nested-PCR assay amplified the partial fragment of the BoGHV6 polymerase gene derived from the pulmonary tissue with interstitial pneumonia. Phylogenetic analysis revealed that the BoGHV6 strain herein identified had 99.8% nucleotide (nt) sequence identity with reference strains of BoGHV6, but only 72.2-73.5% and 67.9-68.6% nt identity with reference strains of MCFV and PLHV, respectively. Consequently, these results suggest that BoGHV6 was associated with the pulmonary disease observed in this cow.

Case report: Mixed infection of bovine papillomaviruses associated with squamous papilloma of the upper alimentary tract in a dairy cow

Bovine papillomavirus (BPV) infection can induce neoplastic lesions in both cutaneous and mucosal epithelia in cattle. This study describes the BPV types associated with proliferative lesions with diverse histopathological features present in the upper alimentary tract of a dairy cow suffering from chronic diarrhea from Midwestern Brazil. At autopsy, warts and plaques composed of multiple spherical nodules were observed in the esophageal mucosa, the areas surrounding and constricting the opening of the cardia, and the rumen pillars. One esophageal papillomatous proliferative lesion and a smooth-surfaced proliferative lesion located at the rumen entrance were evaluated by histopathological and molecular analyses. PCR amplification of partial fragments of the BPV L1 and E1 genes was performed followed by sequencing of the obtained amplicons. Upon histopathological evaluation, the esophageal lesion was classified as a squamous papilloma, whereas the other ruminal proliferative lesion consisted of a fibropapilloma. Direct sequencing of PCR products obtained from ruminal fibropapilloma DNA revealed the presence of BPV2. Sequencing of inserts from selected clones containing partial fragments of the BPV L1 and E1 genes revealed a mixed infection of BPV types 2 and 4 in the esophageal squamous papilloma. The findings reported in our investigation reinforce the association of BPV with benign lesions of the bovine alimentary tract in both single and mixed infections, as previously demonstrated to occur in a buffalo. In addition, this report represents the documentation of the occurrence of massive alimentary papillomatosis associated with BPV types 2 and 4 in cattle raised on lands without infestation by bracken fern in Midwestern Brazil.

Ovine gammaherpesvirus 2 infections in cattle without typical manifestations of sheep-associated malignant catarrhal fever and concomitantly infected with bovine coronavirus

Sheep-associated malignant catarrhal fever (SA-MCF) is a severe, frequently fatal, lymphoproliferative disease that affects a wide variety of ruminants and is caused by ovine gammaherpesvirus 2 (OvHV-2), a member of the MCF virus (MCFV) complex. The typical clinical manifestations of SA-MCF are well known and easily recognized by veterinarians, resulting in clinical diagnosis of MCF when characteristic clinical signs are present. This article describes the findings observed in cattle infected with OvHV-2 but without typical clinical manifestations of SA-MCF. Three calves with episodes of diarrhea before death and a yearling that died suddenly were investigated. Gross alterations were not suggestive of SA-MCF. Histopathology revealed a combination of proliferating vascular lesions (PVLs) and necrotizing vasculitis in three animals (two calves and the yearling); with PVLs being identified only at the carotid rete mirabile of two calves infected with OvHV-2. Additional significant histopathologic lesions included atrophic enteritis, portal lymphocytic hepatitis, interstitial pneumonia, suppurative bacterial bronchopneumonia, and pulmonary hemorrhage. An immunohistochemical assay designed to identify only antigens of MCFV revealed, positive, intralesional, intracytoplasmic immunoreactivity within epithelial cells of multiple tissues of all animals with PVLs. PCR assays amplified OvHV-2 DNA from multiple tissues of the animals that contained MCFV proteins, confirming the MCFV identified as OvHV-2. Additionally, bovine coronavirus (BCoV) nucleic acids were amplified from tissues of all animals, including the animal not infected by OvHV-2. Collectively, these findings confirmed the participation of OvHV-2 in the development of the disease patterns observed in these animals that were concomitantly infected by BCoV and provide additional confirmation that cattle can be subclinically infected with OvHV-2. Consequently, the real occurrence of OvHV-2-related disease may be more elevated than reported, since asymptomatic or subclinically infected animals are not likely to be investigated for OvHV-2. Furthermore, PVLs should be included as possible histologic indicators of OvHV-2-related diseases in ruminants.

Seneca Valley virus induces immunodepressionin suckling piglets by selective apoptosis of B lymphocytes

Seneca Valley virus (SVV) is the causative agent of an emerging infectious vesicular disease in swine that is clinically indistinguishable from other vesicular diseases of swine. This study utilized healthy suckling piglets (control) and SVV-naturally infected suckling piglets to determine the effects of SVV on lymphoid tissues and determined the SVV RNA load by quantitative RT-PCR (qRT-PCR). Furthermore, immunohistochemistry (IHC) analyses were performed to quantify the expression of T and B cell lymphocytes, natural killer cells, cleaved caspase 3, and ki-67. The main histopathologic finding in the infected group was severe lymphoid depletion. The highest average of SVV RNA load by qRT-PCR (Log¹⁰ genomic copies/g of tissue) occurred at the spleen (8.54 ± 0.8), followed by the tonsils (8.04 ± 1.42), and mesenteric lymph nodes (6.90 ± 1.42). The IHC analyses revealed that there was an increased in cellular apoptosis with concomitant reduction in the proliferation of B cells. The results from this study have demonstrated that SVV-infected piglets exhibited decreased lymphocyte density probably due to lymphoid apoptosis, affecting particularly B-cells lymphocytes.

Detection and Quantification of the E6 Oncogene in Bovine Papillomavirus Types 2 and 13 From Urinary Bladder Lesions of Cattle

Bovine papillomavirus types 2 and 13 can induce tumors in both the cutaneous and mucosal epithelia of cattle. These viral types are associated with the development of benign cutaneous papillomas and malignant lesions in the urinary bladders of cattle, with the latter being known as bovine enzootic hematuria. Among the viral oncoproteins encoded by Deltapapillomavirus DNA, the E6 oncoprotein has an important role in cell proliferation and might be related to cancer initiation and promotion. The aim of this study was to present a standardized SYBR Green-based quantitative PCR for detection and quantification of the bovine papillomavirus 2 and 13 E6 oncogenes in urinary bladder samples from cattle. Twenty-four urinary bladders from cattle displaying tumors (n = 12) and normal bladder mucosa (n = 12) were tested by quantitative PCR. Of the 12 urinary bladders with tumors, six presented bovine papillomavirus 2 DNA concentrations ranging from 1.05 × 10⁴ to 9.53 × 10³ copies/μL, while two had bovine papillomavirus 13 DNA amplified at concentrations of 1.30 × 10⁴ to 1.23 × 10⁴ copies/μL. The healthy bladder mucosa samples were negative for both bovine papillomaviruses. Once the results were confirmed by conventional PCR and direct sequencing, the quantitative PCR assay developed in this study was shown to be a sensitive and specific tool for detecting and quantifying the E6 ORF of bovine papillomavirus 2 and 13 in a variety of clinical samples. Our findings of identification of bovine papillomavirus 2 and 13 DNA in urothelial tumors from cattle suffering from bovine enzootic hematuria agree with data from previous studies, representing the first detection of bovine papillomavirus 13 DNA in malignant bladder lesions of cattle from Brazil.

Porcine rotavirus B as primary causative agent of diarrhea outbreaks in newborn piglets

Rotavirus (RV) is considered a major cause of acute viral gastroenteritis in young animals. RV is classified into nine species, five of which have been identified in pigs. Most studies worldwide have highlighted diarrhoea outbreaks caused by RVA, which is considered the most important RV species. In the present study, we described the detection and characterization of porcine RVB as a primary causative agent of diarrhoea outbreaks in pig herds in Brazil. The study showed a high frequency (64/90; 71.1%) of RVB diagnosis in newborn piglets associated with marked histopathological lesions in the small intestines. Phylogenetic analysis of the VP7 gene of wild-type RVB strains revealed a high diversity of G genotypes circulating in one geographic region of Brazil. Our findings suggest that RVB may be considered an important primary enteric pathogen in piglets and should be included in the routine differential diagnosis of enteric diseases in piglets.

Molecular characterization of Brazilian wild-type strains of bovine respiratory syncytial virus reveals genetic diversity and a putative new subgroup of the virus

Background

Bovine orthopneumovirus, formerly known as bovine respiratory syncytial virus (BRSV), is frequently associated with bovine respiratory disease (BRD).

Aim

To perform the molecular characterization of the G and F proteins of Brazilian wild-type BRSV strains derived from bovine respiratory infections in both beef and dairy cattle.

Materials and Methods

Ten BRSV strains derived from a dairy heifer rearing unit (n = 3) in 2011 and steers of three other feedlots (n = 7) in 2014 and 2015 were analyzed. For the BRSV G and F partial gene amplifications, RT-nested-PCR assays were performed with sequencing in both directions with forward and reverse primers used.

Results

The G gene-based analysis revealed that two strains were highly similar to the BRSV sequences representative of subgroup III, including the Bayovac vaccine strain. However, the remaining seven Brazilian BRSV strains were diverse when compared with strains representative of the BRSV I to VIII subgroups. The central hydrophobic region of the Brazilian BRSV G gene showed the replacement of conserved cysteines and other residues of importance to antibody reactivity. The deduced F gene amino acid sequences from the Brazilian BRSV strains showed changes that were absent in the representative sequences of the known subgroups. Viral isolation on the nasopharyngeal swab suspensions failed to isolate BRSV.

Conclusion

Results suggest that these strains represent a putative new subgroup of BRSV with mutations observed in the immunodominant region of the G protein. However, further studies on these Brazilian BRSV strains should be performed to establish their pathogenic potential.

Sanitary program to reduce embryonic mortality associated with infectious diseases in cattle

Among reproductive disorders in dairy and beef cattle worldwide, embryonic mortalities stand out as one of the most frequent. Because of the multifactorial etiology, the clinical and laboratory diagnoses of embryonic mortality causes in cattle are quite complex. Often, infectious causes may account for up to 50% of bovine embryonic mortality rates after 30 days of conception. This review will address the main causes of early and late embryonic mortality, with emphasis on infectious causes and, particularly, those more frequent in the Brazilian cattle herds. In addition, we will discuss ways of controlling and prophylaxis including those related to reproductive and sanitary management, with emphasis on immunoprophylaxis of the three most frequent reproductive infectious diseases in Brazilian dairy and beef cattle herds.

Detection of Equid gammaherpesvirus 2 and 5 DNA in the upper respiratory tract of asymptomatic horses from Southern Brazil

Equid gammaherpesvirus 2 (EHV-2) and 5 (EHV-5) are members of the Herpesviridae family and have been reported in horse populations worldwide. This study aimed to evaluate the presence of herpesvirus DNA in the upper respiratory tract of horses. Twenty-six nasal swabs were collected from asymptomatic adult horses of two different horse farms (A, n = 18; B, n = 8), both located in Southern Brazil. The EHV-1, EHV-2, EHV-4, and EHV-5 DNA analyses were performed using nested PCR assays targeting the glycoprotein B gene. Four (15.3%) and 12 (46.1%) of the 26 nasal swab samples were positive for the EHV-2 and EHV-5, respectively. Four (15.3%) horses were detected with both viruses simultaneously. DNA of EHV-2 and EHV-5 in both single and mixed infections was identified in horses from both herds. All swab samples were negative for EHV-1 and EHV-4. This study reports the first detection of EHV-2 and EHV-5 in the upper respiratory tracts of horses in Brazil. The high detection rate of EHV-2 and EHV-5 in asymptomatic adult horses demonstrates that these gammaherpesviruses are circulating in Brazil.

Seneca Valley virus RNA detection in pig feed and feed ingredients in Brazil

We investigated Seneca Valley virus (SVV) contamination in pig feed and feed ingredients. Twenty-seven samples were collected from two Brazilian feed mills and subjected to conventional RT-nested-PCR and qRT-PCR assays. Seven samples were SVV-positive with viral loads of 3.94-4.33 log₁₀ genomic copies/g of feed. The study reveals SVV feed and feed ingredient contamination under natural conditions in Brazil.