High frequency of bovine viral diarrhea virus type 2 in Southern Brazil

Respiratory illness in young and adult cattle caused by bovine viral diarrhea virus subgenotype 2b in singular and mixed bacterial infection in a BVDV-vaccinated dairy herd

Bovine respiratory disease (BRD) is a common global health problem in dairy cattle. The definitive diagnosis of BRD is complex because its etiology involves several predisposing and determining factors. This report describes the etiology of a BRD outbreak in a dairy herd in the mesoregion of Central Eastern Paraná, which simultaneously affected young (calves and heifers) and adult (cows) Holstein-Friesian cattle. Nine biological samples, consisting of five lung samples from two cows and three suckling calves, and four nasal swab samples from heifers, were used for etiological diagnosis. The nucleic acids extracted from lung fragments and nasal swabs were subjected to PCR and RT-PCR assays for partial amplification of the genes of five viruses [bovine viral diarrhea virus (BVDV), bovine alphaherpesvirus 1 (BoAHV1), bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus 3 (BPIV-3), and bovine coronavirus (BCoV)] and four bacteria (Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni) involved in the etiology of BRD. All nine biological samples from the animals with BRD tested negative for BoAHV1, BRSV, BPIV-3, BCoV, and H. somni. Therefore, the involvement of these microorganisms in the etiology of BRD outbreak can be ruled out. It was possible to identify the presence of BVDV and M. bovis in singular and mixed infections of the lower respiratory tract in cattle. BVDV was also identified in two nasal swabs: one as a single etiological agent and the other in association with two bacteria (P. multocida and M. haemolytica). The phylogenetic analysis conducted in the nucleotide sequence of the 5'UTR region and Npro gene of the BVDV amplicons demonstrated that the BVDV field strains of this BRD outbreak belong to subgenotype 2b. To the best of our knowledge, this is the first report of BVDV-2b involvement in the etiology of BRD in Brazil. Finally, it is necessary to highlight that the cattle were obtained from an open dairy herd with biannual vaccinations for BVDV-1a and - 2a.

Sheep abortions associated with Neospora caninum and Toxoplasma gondii infections in multiple flocks from Southern Brazil

Neosporosis and toxoplasmosis are important parasitic causes of abortions in small ruminants. This study verified the occurrence of these diseases in sheep fetuses from Santa Catarina State, Southern Brazil from 2015 to 2022. Sheep fetuses were necropsied with organ sampling for histopathology, and polymerase chain reaction (PCR) for Neospora caninum and Toxoplasma gondii using the Nc5 and SAG2 targets, respectively, in frozen brain tissue. Microbiological culture and RT-PCR for Pestivirus were conducted to discard other abortion causes. One positive fetus for toxoplasmosis was genotyped using multiplex multilocus nested PCR-RFLP (Mn-PCR-RFLP) with ten genetic markers. Fifty-five sheep fetuses were evaluated, with 10 (18.2%) cases of neosporosis and 7 (12.7%) cases of toxoplasmosis, comprising six and four flocks, respectively. Macroscopically, neosporosis abortions exhibited fetal mummification, maceration, and arthrogryposis. Toxoplasmosis abortions showed fetal mummification and maceration. The neosporosis abortions included lymphoplasmacytic myositis (70%; 7/10) and myocarditis (60%; 6/10), in addition to necrotizing encephalitis and gliosis (50%; 5/10). Toxoplasmosis abortions included lymphoplasmacytic necrotizing encephalitis (71.4%; 5/7), lymphoplasmacytic myositis (42.8%, 3/7), and myocarditis (14.3%; 1/7). Through PCR, N. caninum and T. gondii were detected in 6 (60%) and 5 (71.4%) fetuses, respectively. In one fetus, T. gondii genotyping was conducted, which was characterized as atypical genotype ToxoDB #98. All of the cases were negative for Pestivirus and bacterial agents. This study establishes the occurrence of these diseases as causes of abortions, malformations, mummification, and fetal maceration in sheep, with the characterization of an atypical T. gondii genotype in one of the fetuses.

Outbreak of persistently infected heifer calves with bovine viral diarrhea virus subgenotypes 1b and 1d in a BVDV-vaccinated open dairy herd

Bovine viral diarrhea virus (BVDV) infection has a significant economic impact on beef and dairy industries worldwide. Fetal infection with a non-cytopathic strain may lead to the birth of persistently infected (PI) offspring, which is the main event in the epidemiological chain of BVDV infection. This report describes the birth of 99 BVDV-PI heifer calves within 52 days of birth in a regular BVDV-vaccinated Brazilian dairy cattle herd and the subgenotypes of the infecting field strains. This study was conducted in a high-yielding open dairy cattle herd that frequently acquired heifers from neighboring areas for replacement. The farm monitors the birth of PI calves by screening all calves born using an ELISA (IDEXX) for BVDV antigen detection. All calves aged 1-7 days were evaluated. For positive and suspected results, the ELISA was repeated when the calves were close to one month old. A total of 294 heifer calves were evaluated between February and March 2021. Of these, 99 (33.7 %) had positive ELISA results and were considered PI calves. To evaluate the predominant BVDV species and subgenotypes in this outbreak, whole blood samples were collected from 31 calves born during the study period. All samples were submitted to the RT-PCR assay for the partial amplification of the BVDV 5'-UTR region, and these amplicons were subjected to nucleotide sequencing. Phylogenetic analysis identified BVDV-1b and BVDV-1d in 16 and 13 heifer calves, respectively. In two calves, it was not possible to determine the BVDV-1 subgenotype. Detection of PI animals and monitoring of circulating BVDV subgenotype strains are central to disease control. This study shows that regular BVDV vaccination alone may be insufficient to prevent BVDV infection in high-yielding open dairy cattle herds. Other biosecurity measures must be adopted to avoid the purchase of cattle with acute infections by BVDV or BVDV-PI, which can cause a break in the health profile of the herd and economic losses.

Uncommon bovine viral diarrhea virus subtype 1e associated with abortions in cattle in southern Brazil

We characterized bovine viral diarrhea virus (BVDV)-related abortions in cattle and identified the species and subgenotypes in the state of Santa Catarina, southern Brazil. Our RT-PCR assay was positive for BVDV in 5 fetuses from different farms; however, 3 of the 5 fetuses were also PCR-positive for Neospora caninum. In the 5 BVDV-positive fetuses, gross lesions included fetal mummification (1), hepatomegaly (1), subcutaneous edema (1), and perirenal edema (1). Predominant histologic lesions included epicarditis and mild-to-moderate lymphoplasmacytic myocarditis (5), mild multifocal lymphoplasmacytic interlobular pneumonia (4), nephrosis associated with moderate multifocal interstitial nephritis (1), moderate multifocal lymphoplasmacytic necrotic hepatitis (1), and mild multifocal lymphoplasmacytic meningitis (1). The amplification products from the Pestivirus 5'UTR region of 4 of the 5 fetuses had 96.3-100% similarity between fetal strains and reference strains. The samples were distributed into 2 branches of the phylogenetic tree; strains UDESC:01, UDESC:02, and UDESC:05 clustered in the BVDV-1e branch, uncommon in the Americas, and strain UDESC:04 clustered in the BVDV-2b branch. The three 1e strains had 96.9-97.4% similarity.

HoBi-like Pestivirus Is Highly Prevalent in Cattle Herds in the Amazon Region (Northern Brazil)

Pestiviruses are globally distributed and cause substantial economic losses to the cattle industry. In Brazil, the country with the world's largest cattle population, pestivirus infections are well described in some regions, such as in the south, where a high frequency of BVDV-2 is described and contrasts with the high prevalence of HoBi-like pestivirus (HoBiPeV) in the northeast. However, there is a lack of information about pestiviruses in the Amazon Region, in northern Brazil, with a cattle population estimated at 55.7 million head, which has a significant impact on the international livestock market. Therefore, this study investigated the seroprevalence and genetic variability of ruminant pestiviruses in 944 bovine serum samples from four states in northern Brazil: Pará (PA), Amapá (AP), Roraima (RR), and Amazonas (AM). Our results showed that 45.4% of the samples were seropositive (19.8% for BVDV-1, 14.1% for BVDV-2, and 20.9% for HoBiPeV). All samples were tested by RT-qPCR, and three were positive and classified as HoBiPeV in a phylogenetic analysis. These serological and molecular results contrast with those from other regions of the world, suggesting that the northern Brazilian states have a high prevalence of all bovine pestiviruses including HoBiPeV.

Microcephaly and hydrocephalus in a sheep fetus infected with Neospora caninum in Southern Brazil - Short communication

A case of non-communicating hydrocephalus and microcephaly in a sheep fetus infected with Neospora caninum from Lages, Santa Catarina, Brazil, is reported. Macroscopically, there was moderate flattening and narrowing of the skull, and the portion of the cerebral hemispheres was markedly reduced in size, measuring 3.5 × 3.5 × 0.5 cm, with marked diffuse flattening of the brain gyri and dilation of the lateral ventricles. Cerebrospinal fluid samples were positive to N. caninum detection by PCR. Histologically, there was discrete focal lymphoplasmacytic necrotising encephalitis on the floor of the lateral ventricle, discrete multifocal gliosis and discrete multifocal lymphoplasmacytic myositis. Through the molecular detection of N. caninum in the cerebrospinal fluid, it was possible to report what appears to be the first case of non-communicating hydrocephalus and microcephaly in an ovine fetus infected with N. caninum.

Temporal analysis of bovine pestivirus diversity in Brazil

In this study, phylogenetic and evolutionary analyses of cattle pestiviruses (BVDV-1, 2 and HoBiPeV) originating in Brazil were used to investigate the temporal diversification of subgenotypes in the country. Inferred dated phylogeny and time of the most recent common ancestor (tMRCA) demonstrated that some BVDV subgenotypes (1a, 1b, 1d, 1e, and 2b) and HoBi-like sequences clustered according to the region in which they were collected and that the diversification of subgenotypes appears to have occurred around the introduction of first Bos taurus and then Bos indicus, followed by expansion to form the adapted Brazilian breeds. The present results help to elucidate the temporal facts that led to diversification of ruminant pestiviruses in cattle in Brazil.

Cattle influenza D virus in Brazil is divergent from established lineages

Influenza D virus (IDV) is endemic in cattle on several continents and can also infect a wide range of hosts. IDV was first detected in a bovine respiratory disease outbreak associated with bovine alphaherpesvirus 1 in Brazil. Sequence analysis of partial segments showed that the virus is phylogenetically divergent from previously described IDVs from other continents. As the first molecular description of IDV in South America, this can be a first step toward investigating IDV infections in cattle in Brazil and surrounding countries in which the beef industry is economically important.

Bovine viral diarrhea virus subgenotype 1a in a mummified fetus from a Brazilian dairy cattle herd

We describe the molecular analysis of a wild-type field strain of bovine viral diarrhea virus (BVDV) identified in a mummified fetus from a small Brazilian dairy cattle herd. Nucleic acids extracted from samples of the lung, liver, heart, spleen, and kidney were tested by PCR assays for bovine alphaherpesvirus 1, Neospora caninum, Leptospira spp., Histophilus somni, and Brucella abortus, a nested PCR assay for Mycoplasma bovigenitalium and Ureaplasma diversum, and a RT-PCR assay for BVDV. Amplicons were only obtained in the RT-PCR assay for the partial amplification of the BVDV 5'UTR (288 bp) in kidney and spleen samples and the N^pro (438 bp) gene in the kidney sample. Nucleotide sequencing of the amplified products and phylogenetic analyses based on the 2 BVDV genomic regions enabled the BVDV strain to be classified as subgenotype 1a.

Insights into the origin and diversification of bovine viral diarrhea virus 1 subtypes

In this study, we performed phylogenetic and evolutionary analysis on bovine viral diarrhea virus 1 (BVDV-1) sequences to investigate the origin and temporal diversification of different BVDV-1 subtypes. Dated phylogenies using the complete polyprotein sequence were reconstructed, and the time of the most recent common ancestor (tMRCA) was estimated. The results demonstrated that BVDV-1 subtypes clustered into two phylogenetic clades, where the predominant subtypes worldwide grouped together. In the temporal analysis, the tMRCA of BVDV-1 was 1336, and the diversification into different subtypes appears to have occurred around 363 years ago. The present results help to elucidate the origins of BVDV-1 subtypes and the dynamics of ruminant pestiviruses.

Is contamination of bovine-sourced material with bovine viral diarrhea virus still a problem in countries with ongoing eradication campaigns?

In this report, we describe the detection of bovine viral diarrhea virus (BVDV) contamination in commercial animal-derived sera and vaccines against animal viral pathogens on the market in Poland. Antibodies against BVDV were detected in 4/45 sera samples (8.9%) using an ELISA test. The presence of BVDV antigen was found using ELISA in 3/45 serum samples (6.6%) and 18/172 vaccine samples (10.5%). An RT -PCR was conducted using primers targeting two genome regions, the five prime untranslated region (5’UTR) and N-terminal protease (Npro). BVDV RNA was detected in 33/45 (73.3%) of sera, and 11/172 samples (6.4%) of collected vaccines, of which one vaccine did not declare BVDV strain in its composition. A single serum showed the presence of an infectious virus and only one was contaminated with all 3 species of BVDV. The most frequent species in sera was BVDV-3 (75.5%), whereas in vaccines only BVDV-1 was identified. Sequence analysis showed that the tested commercial sera and one vaccine were contaminated by six genotypes of BVDV: -1a, -1b, -1c, -1d, -2a, and -3. Identification of BVDV and its genetic material in animal-derived products is important due to the possibility of pestivirus transmission as well as the chance of falsifying the results of a diagnostic test. It also demonstrates the necessity of rigorous monitoring of the bioproducts used at the laboratory and industry level.

Bovine Viral Diarrhea Virus: Recent Findings about Its Occurrence in Pigs

Bovine viral diarrhea virus (BVDV) is an important pathogen belonging to the Pestivirus genus, Flaviviridae family, which comprises viral species that causes an economic impact in animal production. Cattle are the natural host of BVDV and the main source of infection for pigs and other animal species. Due to its antigenic and genetic similarity with other important pestiviruses such as Classical Swine Fever Virus (CSFV), several studies have been conducted to elucidate the real role of this virus in piglets, sows, and boars, not only in the field but also in experimental infections, which will be discussed in this paper. Although BVDV does not pose a threat to pigs as it does to ruminants, the occurrence of clinical signs is variable and may depend on several factors. Therefore, this study presents a survey of data on BVDV infection in pigs, comparing information on prevalence in different countries and the results of experimental infections to understand this type of infection in pigs better.

Survey for pestiviruses in backyard pigs in southern Brazil

The Pestivirus genus comprises species that affect animal health and productivity worldwide. Members of the Suidae family are hosts for classical swine fever virus (CSFV), an important pathogen tracked by the World Organization for Animal Health (OIE). However, swine are also susceptible to other pestivirus species that can result in disease or compromise CSFV detection. We searched for pestivirus infection in swine sera collected from 320 backyard pig herds in southern Brazil. We used reverse-transcription PCR primers for Bungowannah virus; atypical porcine pestivirus (APPV); and a panpestivirus pair that detects bovine viral diarrhea virus (BVDV)-1, -2, and HoBi-like pestivirus (HoBiPeV), border disease virus (BDV), and CSFV. Two samples were positive using the panpestivirus primer pair and were classified as BVDV-1d and -2a, respectively. Serum samples were tested for virus neutralization against BVDV-1a, -1b, and -2 strains, resulting in 28 (4.4%) positive samples. Of those, 16 samples had the highest titers against BVDV-1a (2), BVDV-1b (5), and BVDV-2 (9). Our results indicate that Bungowannah virus, APPV, CSFV, BDV, and HoBiPeV have not been circulating in these specific backyard swine populations. However, ruminant pestiviruses were detected and must be considered in future pestivirus control programs conducted in Brazil.

Trueperella pyogenes como causa de aborto em uma vaca - relato de caso

RESUMO Trueperella pyogenes é uma bactéria oportunista que causa mastite, metrite e abortos esporádicos em bovinos. Este trabalho relata um caso incomum de abort em uma vaca por Trueperella pyogenes. Um feto bovino, fêmea, mestiço Brahman, com oito meses de gestação, foi encaminhado para exame anatomopatológico e exames complementares. Na necropsia, evidenciou-se grande quantidade de líquido serossanguinolento e moderada quantidade de fibrina recobrindo a pleura visceral e o saco pericárdico. Os pulmões estavam difusamente avermelhados e consolidados, com áreas firmes esbranquiçadas ao corte de não mais de 1cm. No exame histopatológico, observou-se pneumonia necrossupurativa, pleurite fibrinopurulenta e placentite purulenta. No exame microbiológico, isolou-se T. pyogenes nas amostras de fígado, pulmões, conteúdo abomasal do feto e placenta. O feto foi negativo na PCR para Neospora caninum, Toxoplasma gondii e vírus da diarreia viral bovina (BVDV). Trueperella pyogenes geralmente causa broncopneumonia supurativa com formação de abscessos, porém, no presente feto abortado, observaram-se lesões macro e microscópicas comumente descritas em casos de aborto por Brucella abortus. Este estudo constata, então, a importância dessa bactéria como causa de aborto em bovinos, com lesões semelhantes à brucelose, destacando sua relevância dentro das causas de aborto em bovinos e o potencial zoonótico pouco explorado.

An extensive field study reveals the circulation of new genetic variants of subtype 1a of bovine viral diarrhea virus in Uruguay

Bovine viral diarrhea virus (BVDV) is a major pathogen worldwide, causing significant economic losses to the livestock sector. In Uruguay, BVDV seroprevalence at the farm level is >80%. In this work, 2546 serum, blood or tissue samples collected from animals suspected of being affected by BVD between 2015 and 2017 were analyzed by reverse transcription PCR and sequencing. Analysis of the BVDV genomic regions 5'UTR/N^pro, N^pro and E2 revealed that BVDV-1a, 1i and 2b circulate in the country, with BVDV-1a being the most prevalent subtype. Population dynamics studies revealed that BVDV-1a has been circulating in our herds since ~1990. This subtype began to spread and evolve, accumulating point mutations at a rate of 3.48 × 10^-3 substitutions/site/year, acquiring specific genetic characteristics that gave rise to two local genetic lineages of BVDV-1a. These lineages are divergent from those circulating worldwide, as well as the vaccine strain currently used in Uruguay. The most notable differences between field and vaccine strains were found in the E2 glycoprotein, suggesting that the amino acid substitutions could result in failure of cross-protection/neutralization after vaccination. This is the first study that compares Uruguayan BVDV field and vaccine strains with other BVDV strains from throughout the world. The results obtained in this study will be very useful for developing a suitable immunization program for BVDV in Uruguay by identifying local field strains as candidates for vaccine development.

Diseases associated with bovine viral diarrhea virus subtypes 1a and 2b in beef and dairy cattle in Uruguay

Bovine viral diarrhea virus (BVDV, Pestivirus) causes significant economic losses to the livestock industry worldwide. Although serological surveys show that BVDV exposure is widespread in cattle in Uruguay, BVDV-associated diseases are greatly underreported. The aim of this work is to describe the epidemiological, clinical, pathological, and virological findings from spontaneous outbreaks of BVDV-associated diseases in cattle in Uruguay. Diagnostic investigations were performed during 6 spontaneous disease outbreaks on beef and dairy cattle farms in the departments of Colonia, Rio Negro, and Soriano between November 2016 and April 2018. Carcasses of 8 naturally deceased cattle from these outbreaks were necropsied and subjected to histological examination and immunohistochemistry to detect BVDV antigen in the tissues. Reverse transcription real-time PCR and genomic sequencing were also performed to identify BVDV at the species and subtype levels. Other ancillary diagnostic tests, including bacterial cultures, were performed on a case-by-case basis to rule in/out differential diagnoses based on initial clinicopathological presumptive diagnoses. BVDV-associated conditions that were diagnosed in the 8 cases included mucosal disease, transient postnatal BVDV infections associated with digestive/septicemic salmonellosis by Salmonella serovar typhimurium, Histophilus somni bronchopneumonia, urinary tract coinfections with Escherichia coli and Streptococcus sp., enteric coinfection with coccidia, and transplacental fetal infections and abortions with Neospora caninum coinfection. BVDV-1a and BVDV-2b were each identified in four of the eight cases. We conclude that BVDV-1a and BVDV-2b contribute significantly to disease and mortality in cattle in Uruguay. Future research should estimate the economic impact of BVDV in the Uruguayan livestock sector.

A genetic profile of bovine pestiviruses circulating in Brazil (1998-2018)

The pestiviruses bovine viral diarrhea virus 1 (BVDV-1), 2 (BVDV-2), and HoBi-like (HoBiPeV) are endemic among Brazilian cattle, the world's largest commercial bovine herd. In the last two decades (1998-2018) over 300 bovine pestiviruses have been partially or fully sequenced in Brazil, including viruses from different regions, different epidemiological backgrounds, and associated with diverse clinical presentations. Phylogenetic analysis of these viruses demonstrated a predominance of BVDV-1 (54.4%), with subgenotypes -1a (33.9% of total) and -1b (16.3%) being more frequent and subgenotypes -1d, -1e, and -1i at very low frequencies. The overall BVDV-2 frequency was 25.7% but it varied largely by region, reaching up to 48% in Southern states. BVDV-2b was the predominant subgenotype (84.8% of BVDV-2), followed by BVDV-2a (8.86%). HoBiPeV accounted for 19.9% (61/307) of the genotyped viruses and were detected at high frequency in cattle from Northeastern states. These findings demonstrate a unique mix of pestivirus species and subgenotypes, unlike that seen in Europe or North America. The design of effective diagnostic tools, vaccines, and control programs for limiting bovine pestivirus infections in Brazil must take into consideration this unique mix of viruses. This article provides a critical review of two decades of genetic identification of pestiviruses in Brazil.

Genetic identification of pestiviruses from beef cattle in Southern Brazil

Bovine pestiviruses, e.g., bovine viral diarrhea virus types 1 (BVDV-1 or Pestivirus A), BVDV-2 (Pestivirus B), and HoBi-like pestiviruses (HoBiPeV or Pestivirus H), have been shown to circulate in Brazilian cattle in varied proportions. In this study, we identified genetically pestiviruses circulating in beef cattle in Rio Grande do Sul, the southern most Brazilian state. Screening of serum of 15.584 beef calves destined to be export by an antigen capture ELISA and, subsequently, by reverse-transcription polymerase chain reaction (RT-PCR), revealed 135 containing pestivirus RNA. Genetic typing of these viruses based on nucleotide sequencing and phylogenetic analysis of the 5' untranslated region (5' UTR) of the viral genome allowed for the identification of 90 different viruses, being 38 BVDV-1 (42.2%), 31 BVDV-2 (34.4%), and 21 HoBiPeV (23.4%). Among BVDV-1, only subtypes BVDV-1a (n = 28, 31.1%) and BVDV-1b (n = 10, 11.1%) were identified. All 31 BVDV-2 isolates belonged to BVDV-2b subtype and the 21 HoBiPeV viruses clustered to subgroup 3a. Thus, this study provides an approximate genetic profile of pestiviruses circulating in beef cattle in a traditional Brazilian beef cattle-raising state.

Molecular detection and phylogeny of bovine viral diarrhea virus 1 among cattle herds from Northeast, Southeast, and Midwest regions, Brazil

We examined the circulating BVDV species and genotypes among cattle herds from Northeast, Southeast, and Midwest regions in Brazil. A total of 77 animals tested positive through standard PCR. Phylogenetic analyses revealed the presence of BVDV-1a, highlighting the need for better surveillance strategies to prevent BVDV spread in the country.

Genetic Diversity of Bovine Viral Diarrhea Virus Infection in Goats in Southwestern China

Bovine viral diarrhea virus (BVDV) affects cows, pigs, sheep, goats, and other ruminants, as well as some wild animals. BVDV causes considerable economic losses every year and many countries have developed programs aimed at the eradication of this disease. The genetic diversity of BVDV in diseased goats has never been described in southwestern China. Thus, in this study, we applied antigen-capture ELISA and RT-PCR to survey the infection rate of BVDV in diseased goats in this region. Our results demonstrated that the average BVDV infection rate in goats was 17.51%, with all positive samples indicating infection by BVDV-1 and not BVDV-2, BVDV-3, or Border disease virus. The molecular characteristics of the 5′-untranslated region (5′-UTR) of BVDV-1 were recognized as belonging predominantly to the BVDV-1a, 1b, 1c, 1m, and 1p subtypes. BVDV-1b and 1m were the most abundant subtypes identified in this region, similar to the BVDV epidemics in cattle in other regions of China. This is the first study that describes the genetic characterization of BVDV in sick goats from southwestern China and is important for future studies and control programs.

Evaluation of the serum virome in calves persistently infected with Pestivirus A, presenting or not presenting mucosal disease

Bovine viral diarrhea virus 1, reclassified as Pestivirus A, causes an economically important cattle disease that is distributed worldwide. Pestivirus A may cause persistent infection in that calves excrete the virus throughout their lives, spreading the infection in the herd. Many persistently infected (PI) calves die in the first 2 years of life from mucosal disease (MD) or secondary infections, probably as a consequence of virus-induced immune depression. Here, high-throughput sequencing (HTS) was applied for evaluation of the total virome in sera of (i) PI calves displaying clinically apparent MD (n = 8); (ii) PI calves with no signs of MD (n = 8); and (iii) control, Pestivirus A-free calves (n = 8). All the groups were collected at the same time and from the same herd. Serum samples from calves in each of the groups were pooled, submitted to viral RNA/DNA enrichment, and sequenced by HTS. Viral genomes of Pestivirus A, Ungulate erythroparvovirus 1, bosavirus (BosV), and hypothetical circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses were identified. Specific real-time PCR assays were developed to determine the frequency of occurrence of such viruses in each of the groups. The absolute number of distinct viral genomes detected in both PI calf groups was higher than in the control group, as revealed by higher number of reads, contigs, and genomes, representing a wider range of taxons. Genomes representing members of the family Parvoviridae, such as U. erythroparvovirus 1 and BosV, were most frequently detected in all the three groups of calves. Only in MD-affected PI calves, we found two previously unreported Hypothetical single-stranded DNA genomes clustered along with CRESS-DNA viruses. These findings reveal that parvoviruses were the most frequently detected viral genomes in cattle serum; its frequency of detection bears no statistical correlation with the status of calves in relation to Pestivirus A infection, since clinically normal or MD-affected/non-affected PI calves were infected with similar U. erythroparvovirus 1 genome loads. Moreover, MD-affected PI calves were shown to support viremia of CRESS-DNA viral genomes; however, the meaning of such correlation remains to be established.

Experimental inoculation of gilts with bovine viral diarrhea virus 2 (BVDV-2) does not induce transplacental infection

Bovine viral diarrhea virus (BVDV) belongs to the genus Pestivirus and can cause reproductive problems in cattle. However, there is still a lack of research to clarify its pathogenicity in different gestational periods of sows and its effects in neonates. In this study, 12 gilts divided into groups (G) were experimentally inoculated with the strain BVDV-2 (SV-253) oronasally at a dose of 10⁶·⁸⁵ TCID50; one group was inoculated 30 days before insemination (G0; n = 2), three groups were inoculated during gestation (first (G1; n = 2), second (G2; n = 3), third (G3; n = 3)), and a fourth was the control group (G4; n = 2). Samples of blood and nasal swabs from the gilts were collected every three days until delivery for a virus neutralization (VN) test, qRT-PCR, and blood count. On the day of delivery, 40% of the neonates were euthanized to obtain tissue and blood samples at necropsy for histopathology and qRT-PCR. The sows were seroconverted between 12 and 33 days after inoculation, and the virus was detected in the blood between 3 and 12 days and on the nasal swab between 6 and 24 days in the G0, G1, G2 and G3 sows but was not detected in piglet tissues, and no significant alterations were found through histopathology. The mean and standard deviation of the mean cycles (Cq) from blood (Cq = 34.87 ± 0.60) and nasal swab (Cq = 34.61 ± 0.87) samples were between 107 and 490 TCID50/ml. Transient infection was demonstrated with a low viral load, but transplacental infection was not possible in gilts.

Mucosal disease-like lesions caused by HoBi-like pestivirus in Brazilian calves in 2010-2011: Clinical, pathological, immunohistochemical, and virological characterization

A HoBi-like pestivirus was first described in 2004 in a Brazilian fetal bovine serum that was exported to Germany. Nevertheless, it is believed that the virus had been present since the 1990's, when it was detected in buffalos of Brazilian origin. Reproductive and respiratory diseases have been reported since 2001 in cattle, and more recently, diseases accompanied by a clinical presentation of mucosal disease-like (MD-like lesions have been reported as well. In the present study, the authors reported the oldest case of MD--like in cattle, associated with a HoBi-like pestivirus infection. Diarrhea, anorexia, nasal discharge, hypersalivation, and weakness were observed in 20 calves. For two of the animals, clinical follow-ups were performed. Following their death, necropsy was performed on these two calves. The main gross alterations observed were ulcers and erosions in the upper and lower digestive tract and interdigital dermatitis. Clinical history, gross findings, histopathological examination, immunohistochemistry, RT-PCR, and virus isolation were determined as suitable tools for the diagnosis of a MD-like outbreak, caused by a HoBi-like pestivirus.

Spatial analysis for bovine viral diarrhea virus and bovine herpesvirus type 1 infections in the state of Paraíba, northeastern Brazil

BACKGROUND

Bovine Viral Diarrhea Virus (BVDV) and Bovine Herpesvirus type 1 (BoHV-1) cause reproductive problems in cattle and restrictions on international trade in animals worldwide. Both infections were detected in cattle herds in the Paraíba state, Northeastern Brazil, however, the spatial distribution and geographic identification of positive herds for these viruses has never been examined. Therefore, the aim of this study was to describe the spatial pattern of apparent prevalence estimate and to identify spatial clustering of positive herds of BVDV and BoHV-1 infections in cattle herds from the state of Paraíba, Northeastern Brazil.

RESULTS

The herd-level prevalence for BVDV and BoHV-1 infections in Paraíba were, respectively, 65.5% (95% CI: 61.1-69.7) and 87.8% (95% CI: 84.5-90.5). The average apparent within-herd prevalence of BVDV was 31.8% and of BoHV-1 was 62.4%. The predicted prevalence was highest (0.42-0.75) for BVDV in the west, north and eastern part of Sertão and in the central and eastern part of Agreste/Zona da Mata. For BoHV-1, the highest predicted prevalence (0.74-0.97) was in some local areas across Sertão and throughout the eastern part of Agreste/Zona da Mata. Six significant clusters were detected for BVDV, a primary cluster covering the eastern Sertão region, with 11 herds, radius of 24.10 km and risk relative (RR) of 2.21 (P <  0.001) and five smaller significant clusters, involving one or two herds in Agreste/Zona da Mata region with a high RR. A significant clustering of BoHV-1 positive herds (P <  0.001) was detected in Agreste/Zona da Mata region with a radius of 77.17 km and a RR of 1.27, with 103 cases. Consistency was found between kriging and SatScan results for identification of risk areas for BVDV and BoHV-1 infections.

CONCLUSIONS

The clusters detected contemplated different areas of the state, with BVDV cluster located in the Sertão and BoHV-1 in Agreste/Zona da Mata stratum. Through the risk mapping, it was possible to identify the areas in which the risk is significantly elevated, coincided with areas where there are borders with other states and in which there is a high movement of animals.

Variability and Global Distribution of Subgenotypes of Bovine Viral Diarrhea Virus

Bovine viral diarrhea virus (BVDV) is a globally-distributed agent responsible for numerous clinical syndromes that lead to major economic losses. Two species, BVDV-1 and BVDV-2, discriminated on the basis of genetic and antigenic differences, are classified in the genus Pestivirus within the Flaviviridae family and distributed on all of the continents. BVDV-1 can be segregated into at least twenty-one subgenotypes (1a–1u), while four subgenotypes have been described for BVDV-2 (2a–2d). With respect to published sequences, the number of virus isolates described for BVDV-1 (88.2%) is considerably higher than for BVDV-2 (11.8%). The most frequently-reported BVDV-1 subgenotype are 1b, followed by 1a and 1c. The highest number of various BVDV subgenotypes has been documented in European countries, indicating greater genetic diversity of the virus on this continent. Current segregation of BVDV field isolates and the designation of subgenotypes are not harmonized. While the species BVDV-1 and BVDV-2 can be clearly differentiated independently from the portion of the genome being compared, analysis of different genomic regions can result in inconsistent assignment of some BVDV isolates to defined subgenotypes. To avoid non-conformities the authors recommend the development of a harmonized system for subdivision of BVDV isolates into defined subgenotypes.

Effects of oocytes exposure to bovine diarrhea viruses BVDV-1, BVDV-2 and Hobi-like virus on in vitro-produced bovine embryo development and viral infection

As production of in vitro (IVP) bovine embryos steadily increases, the sanitary risk associated with IVP embryos remains a concern. One of the greatest concerns is how BVDV may be transmitted through IVP embryos. The objective of this study was to evaluate the effects caused by BVDV-1, BVDV-2 and Hobi-like virus exposure during in vitro maturation on embryo development and viral infection. Abittior-derived oocytes were randomly assigned for in vitro maturation with serial concentrations of BVDV-1 (3.12 × 10² - 2.50 × 10³ TCID₅₀/100 μL), BVDV-2 (6.25 × 10¹ - 5.20 × 10² TCID₅₀/100 μL) or Hobi-like virus (1.90 × 10² - 1.58 × 10³ TCID₅₀/100 μL) for 22-24 h. After maturation, oocytes were fertilized and embryo cultured following standard in vitro procedures. Embryo development was evaluated and percentage of respective, positive BVDV degenerated and viable embryos were evaluated by RT-qPCR. No concentration of BVDV-1 altered embryo development as measured by cleavage and blastocyst rates, compared to negative control group. However 100% of degenerated embryos and 50-100% of viable embryos tested positive for BVDV-1, depending on the viral concentration. BVDV-2 exposed oocytes had higher cleavage rates than the negative control group (60.2-64.1% vs 49.8%; P = 0.003-0.032). However, no difference was detected for blastocyst rates. In aadition, 100% of degenerated embryos and 20-50% of viable embryos tested positive for BVDV-2. Hobi-like virus treated oocytes had reduced cleavage rates for the three highest viral concentrations (33.3-38.0% vs 49.8% for negative controls; P ≤ 0.001-0.014). Blastocyst rates were only reduced in the 7.9 × 10² Hobi-like virus concentration (6.9 ± 0.9% vs 15.1 ± 1.6%; P = 0.009), when calculated by oocyte number. 50-80% of degenerated embryos tested positive for Hobi-like virus. No viable embryos from the Hobi-like virus treated oocytes tested positive. These results suggest that IVP embryos from BVDV-1 and -2 infected oocytes develop normally, but carry the virus. However, Hobi-like virus infected oocytes had reduced cleavage and cause pre-implantation embryo loss, but viable embryos did not carry the virus.

Genetic typing of bovine viral diarrhoea virus in cattle on Irish farms

The aim was to carry out a phylogenetic study of bovine viral diarrhoea viruses (BVDV) circulating in Irish cattle herds from 2011 to 2014. Three hundred and twenty five viruses from 267 herds were subtyped by nucleotide sequence analysis of the 5'UTR and/or the N^pro regions. All viruses investigated in this study belonged to species BVDV-1 with BVDV-1a as the prominent subtype (97%). Subtypes BVDV-1b, BVDV-1d and BVDV-1e were also identified for the first time in Ireland. Pairwise alignments of 225 viruses with complete sequences for the 5'UTR and the N^pro regions were performed to determine a low conflict threshold for virus strain demarcation. One hundred and seventy seven unique virus strains were identified. The study revealed significant levels of herd specific clustering of strains but no geographical or temporal clustering. Similar virus strains were identified in different counties, provinces and years indicating the potential to investigate the epidemiology of the disease by combining sequence analysis with animal movement data.

Natural Outbreak of BVDV-1d-Induced Mucosal Disease Lacking Intestinal Lesions

Bovine viral diarrhea virus (BVDV) belongs to the Pestivirus genus, which is further divided into subgenotypes (1a-1u and 2a-c). When persistent infection occurs, the calf will be immunotolerant to BVDV and possibly develop mucosal disease. This study describes an outbreak of BVDV-1d-induced mucosal disease lacking intestinal lesions. Eleven calves presented with anorexia, sialorrhea, lameness, recumbency, and death. Three calves were necropsied, showing ulceration of the interdigital skin and the oral and nasal mucosa; linear ulcers in the tongue, esophagus, and rumen; and rounded ulcers in the abomasum. Microscopically, mucosa and skin had superficial necrosis, with single-cell necrosis and vacuolation in epithelial cells, and severe parakeratosis. Immunohistochemistry (IHC) showed BVDV antigen in the cytoplasm of epithelial cells in skin and mucosa. All 11 dead calves were positive upon reverse transcription-polymerase chain reaction (RT-PCR) for the detection of Pestivirus along with another 11 live calves from the herd, which were positive again by RT-PCR and IHC after a 4-week interval. Sequencing of the 5' untranslated region and N-terminal protease showed that viruses from these 22 calves were homologous and of subgenotype BVDV-1d. Cytopathic BVDV was isolated from 8 of 11 dead calves, but only noncytopathic BVDV was isolated from the 11 live animals. The findings indicate that this was an outbreak of mucosal disease caused by BVDV-1d, with high morbidity, and lesions restricted to the upper alimentary system and skin and absent from intestine. Thus, the epidemiological and pathological features in this form of mucosal disease may be similar to vesicular diseases, including foot and mouth disease.

Molecular diversity of bovine viral diarrhea virus in uruguay

Bovine viral diarrhea (BVD) affects bovine production and reproduction causing significant economic losses all over the world. Two viral species has been recognized: BVDV-1 and BVDV-2, both distributed worldwide. Recently, novel specie of BVDV named HoBi-like pestivirus was discovered. The presence of BVDV was confirmed in 1996 in Uruguay, however, does not exist until today a schedule of compulsory vaccination along the country. Serological studies with samples from all Uruguayan herds were performed during 2000 and 2001 demonstrating that all of them were seropositive to BVDV with a mean prevalence of 69%. In addition, there have been no new studies done since those previously described and it is important to mention that the genetic diversity of BVD has never been described in Uruguay. Nowadays, there is strongly suspect that BVDV is one of the most important causes of reproductive failures in our herds. The aim of this study was to describe for the first time in Uruguay the genetic diversity of BVDV with samples collected from different regions along the country. Serological status of 390 non-vaccinated animals against BVDV with reproductive problems from farms of Rivera, Tacuarembó and Florida departments of Uruguay were studied. All herds were seropositive to BVDV and high proportion of animals were positive (298/390), while 4.1% (16/390) of the animals were positive to Antigen Capture ELISA test and Real Time PCR. Phylogenetic analysis performed with concatenated sequences from the 5'UTR and Npro genomic regions revealed that BVDV-1 and BVDV-2 are infecting our herds, being BVDV-1 the most frequently found. The major subtype was BVDV-1a, followed by BVDV-1i and BVDV-2b. This is the first study that describes the genetic diversity of BVDV in Uruguay and it will contribute to the elaboration of sanitization programs.