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.

Lack of Fetal Protection against Bovine Viral Diarrhea Virus in a Vaccinated Heifer.

The aim of the report was to present the circulation of BVDV (bovine viral diarrhea virus) in the cattle population and determine the cause of the failure of vaccination failure leading to the birth of the PI (persistently infected) calf. The case study was carried out at the BVDV-free animal breeding center and cattle farm, where the vaccination program against BVDV was implemented in 2012, and each newly introduced animal was serologically and virologically tested for BVDV. In this case, a blood sample was taken from a 9-month-old breeding bull. Positive RT-PCR and negative ELISA serology results were obtained. The tests were repeated at 2-week intervals, and the results confirmed the presence of the virus and the absence of specific antibodies, i.e., persistent infection. Additionally, sequencing and phylogenetic analysis were performed, and the BVDV-1d subgenotype was detected. The results of this study showed that pregnant heifers and cows that are vaccinated multiple times with the killed vaccine containing BVDV-1a may not be fully protected against infection with other subgenotypes of BVDV, including their fetuses, which can become PI calves.

Different impact of bovine complement regulatory protein 46 (CD46bov) as a cellular receptor for members of the species Pestivirus H and Pestivirus G.

The genus Pestivirus within the family Flaviviridae comprises highly relevant animal pathogens such as bovine viral diarrhoea virus 1 and 2 (BVDV-1 and -2) classified into the two species Pestivirus A and Pestivirus B, respectively. First described in 2004, HoBi-like pestiviruses (HoBiPeV) represent emerging bovine pathogens that belong to a separate species (Pestivirus H), but share many similarities with BVDV-1 and -2. Additionally, two giraffe pestivirus (GPeV) strains both originating from Kenya represent another distinct species (Pestivirus G), whose members replicate very efficiently in bovine cells. In this study, we investigated the role of bovine complement regulatory protein 46 (CD46bov), the receptor of BVDV-1 and -2, in the entry of HoBiPeV and GPeV. For this purpose, bovine CD46-knockout and CD46-rescue cell lines were generated by CRISPR/Cas9 technology and subsequent trans-complementation, respectively. Our results provide strong evidence that the impact of CD46bov differs between viruses belonging to Pestivirus H and viruses representing Pestivirus G: CD46bov revealed to be a major cellular entry factor for HoBiPeV strain HaVi-20. In contrast, GPeV strain PG-2 presented as largely independent of CD46bov, suggesting a different entry mechanism involving other molecular determinants which remain to be identified. In addition, we demonstrated that, similar to BVDV-1 and -2, virus isolates of both Pestivirus H and Pestivirus G are able to adapt to cell culture conditions by using heparan sulfate to enter the host cell. In conclusion, our findings show that different bovine pestiviruses use diverse mechanisms of host cell entry.

Sequence analysis of the DA domain of glycoprotein E2 of pestiviruses isolated from beef cattle in Southern Brazil.

The envelope glycoprotein E2 of pestiviruses is a major target for neutralizing antibodies. In this study, we analyzed the E2 DA domain of 43 pestiviruses from Southern Brazil. The isolates were identified as Bovine viral diarrhea virus (BVDV) subtypes 1a and 1b or BVDV-2b. Compared to reference strains, the BVDV-1 and -2 isolates had four and two mutations in the DA domain, respectively. All BVDV-2 isolates had a deletion of residues 724 and 725. All mutated amino acids in the BVDV isolates had the same aa substitution, and all were in previously identified antibody binding sites. It is possible that an immunity-mediated selection is acting on the pestiviruses circulating in Southern Brazil.

Failure in dry period vaccination strategy for bovine viral diarrhea virus.

Bovine viral diarrhea is a common disease of cattle and has significant impact on animal welfare worldwide. There are fundamental approaches i.e. elimination of persistently infected animals, vaccination and biosecurity measures for effective control and eradication of BVD virus (BVDV). By this study, the presence of persistent infection with divergent BVDV subgenotype in the calves in a dairy herd having regular vaccination program was investigated. In the herd, vaccinated with a killed whole virion trivalent vaccine (composed of BVDV-1a) during the dry period of the cows, abortion cases were existed in the late autumn 2019. During herd screening by BVDV antigen-ELISA, 2 out of 300 dams were detected positive. Following, by ear notch-based BVDV antigen-ELISA, 30 calves were detected positive. Confirmation of persistent BVDV infection was performed 3 weeks later by testing with antigen-ELISA, where 8 of 9 selected newborn calves were positive for the second time. The entire antigen-ELISA positive samples were subjected to virus isolation on MDBK cell culture and identified as non-cytopathogenic pestiviruses by indirect immunoperoxidase assay. Presence of pestivirus RNA was detected in the 8 isolates by panpestivirus RT-PCR. Analysis of the 5'UTR regions revealed that BVDV-1 r circulate in the herd. Results of this study lead to questioning the efficiency of dry period vaccination strategy against BVDV. But otherwise, vaccination with BVDV-1a can be inefficient for complete protection against BVDV-1 r. Therefore, serological relationship between mentioned subgenotypes or protection by current vaccines against latest field isolates needs to be investigated before development of new BVDV vaccine candidates.

Fetal Lymphoid Organ Immune Responses to Transient and Persistent Infection with Bovine Viral Diarrhea Virus.

Bovine Viral Diarrhea Virus (BVDV) fetal infections occur in two forms; persistent infection (PI) or transient infection (TI), depending on what stage of gestation the fetus is infected. Examination of lymphoid organs from both PI and TI fetuses reveals drastically different fetal responses, dependent upon the developmental stage of the fetal immune system. Total RNA was extracted from the thymuses and spleens of uninfected control, PI, and TI fetuses collected on day 190 of gestation to test the hypothesis that BVDV infection impairs the innate and adaptive immune response in the fetal thymus and spleen of both infection types. Transcripts of genes representing the innate immune response and adaptive immune response genes were assayed by Reverse Transcription quatitative PCR (RT-qPCR) (2-ΔΔCq; fold change). Genes of the innate immune response, interferon (IFN) inducible genes, antigen presentation to lymphocytes, and activation of B cells were downregulated in day 190 fetal PI thymuses compared to controls. In contrast, innate immune response genes were upregulated in TI fetal thymuses compared to controls and tended to be upregulated in TI fetal spleens. Genes associated with the innate immune system were not different in PI fetal spleens; however, adaptive immune system genes were downregulated, indicating that PI fetal BVDV infection has profound inhibitory effects on the expression of genes involved in the innate and adaptive immune response. The downregulation of these genes in lymphocytes and antigen-presenting cells in the developing thymus and spleen may explain the incomplete clearance of BVDV and the persistence of the virus in PI animals while the upregulation of the TI innate immune response indicates a more mature immune system, able to clear the virus.

Detection methods and characterization of bovine viral diarrhea virus in aborted fetuses and neonatal calves over a 22-year period.

Detection of bovine viral diarrhea virus (BVDV) in aborted fetus samples is often difficult due to tissue autolysis and inappropriate sampling. Studies assessing different methods for BVDV identification in fetal specimens are scarce. The present study evaluated the agreement between different diagnostic techniques to detect BVDV infections in specimens from a large number of bovine aborted fetuses and neonatal deaths over a period of 22 years. Additionally, genetic, serological, and pathological analyses were conducted in order to characterize BVDV strains of fetal origin. Samples from 95 selected cases from 1997 to 2018 were analyzed by antigen-capture ELISA (AgELISA), nested RT-PCR (RT-nPCR), and real-time RT-PCR (RT-qPCR). In addition, amplification and sequencing of the 5'UTR region were performed for phylogenetic purposes. Virus neutralization tests against the BVDV-1a, BVDV-1b, and BVDV-2b subtypes were conducted on 60 fetal fluids of the selected cases. Furthermore, the frequency and severity of histopathological lesions were evaluated in BVDV-positive cases. This study demonstrated that RT-nPCR and RT-qPCR were more suitable than AgELISA for BVDV detection in fetal specimens. However, the agreement between the two RT-PCR methods was moderate. The BVDV-1b subtype was more frequently detected than the BVDV-1a and BVDV-2b subtypes. Neutralizing antibodies to any of the three subtypes evaluated were present in 94% of the fetal fluids. Microscopically, half of the BVDV-positive cases showed a mild non-suppurative inflammatory response. These results emphasize the need to consider different methods for a diagnostic approach of BVDV associated to reproductive losses.

Prevalence and genetic diversity of bovine viral diarrhea virus in dairy herds of China.

To determine the nationwide prevalence and genetic diversity of bovine viral diarrhea virus (BVDV) in China, 92 dairy farms with more than 500 animals in 19 provinces of China were surveyed in 2017. At each farm, ear notch samples from calves less than six months old and bulk tank milk (BTM) samples were collected. A total of 901 ear notch samples and 329 BTM samples from 183 tanks were sampled. A total of 20 (20/901, 2.22 %) ear notch samples from 10 (10/92, 10.86 %) farms tested positive for BVDV by IDEXX Antigen Point-of-Care (POC) Test kit and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, 80 of 183 (80/183, 43.7 %) BTM samples from 43 (43/92, 46.7 %) farms were identified as positive by qRT-PCR. The RNA of positive and suspect samples identified by qRT-PCR was subjected to 5'- untranslated region (UTR) amplification by nested RT-PCR and then sequenced. A total of 119 sequences were obtained and phylogenetic analysis of these 5'-UTR sequences revealed the presence of eight different subgenotypes of BVDV-1 including 1a (n = 37, 31.09 %), 1b (n = 5, 4.20 %), 1c (n = 34, 28.57 %), 1d (n = 2, 1.68 %), 1m (n = 25, 21.01 %), 1q (n = 6, 5.04 %), and two unknown subgenotypes which were tentatively typed as "BVDV-1v" (n = 8, 6.72 %) and "BVDV-1w" (n = 2, 1.68 %), respectively. BVDV-1a, 1c, and 1m were the dominant strains, collectively accounting for 80.67 % (96/119) of all sequences. Phylogenetic analysis based on selected N-terminal autoprotease (Npro) sequences confirmed the classification of the 5'-UTR sequences. In conclusion, the prevalence of BVDV persistent infection in dairy cattle was high and genetic diversity was high and increasing, revealing a serious threat to the health of cattle in China and highlighting the need for BVDV control.

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/Npro, Npro 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.

HoBi-like pestivirus infection in an outbreak of bovine respiratory disease.

HoBi-like is an emerging pestivirus of the family Flaviviridae detected in cattle herds and biological products of bovine origin in many parts of the world, causing disease similar to that observed in bovine viral diarrhea virus (BVDV) infections. In this study we reported the detection of HoBi-like pestivirus in an outbreak of respiratory disease in calves from Brazil, seropositive for viruses of the bovine respiratory disease complex (BRDC). Thus, serum samples and nasal swabs were collected from calves up to one year old, presenting or not clinical signs of respiratory disease. Serum samples were submitted to virus neutralization test (VNT) for BVDV-1, BVDV-2, bovine herpesvirus-1 (BoHV-1), bovine respiratory syncytial virus (BRSV) and bovine parainfluenza-3 (BPIV-3). These samples were also tested for the presence of pestiviruses (BVDV-1, BVDV-2 and HoBi-like) and BoHV-1 by RT-PCR and PCR, respectively. Nasal swabs were analyzed by RT-PCR for pestiviruses, BRSV and BPIV-3. VNT results showed high serological prevalence and a wide range of antibodies titers, for all viruses studied, in calves of different age groups. The RT-PCR amplified the 5'UTR and E2 regions of pestiviruses of four calves, from both nasal swabs and serum samples, which sequencing identified the HoBi-like pestivirus. This is the first detection of HoBi-like in nasal secretions of calves in an outbreak of respiratory disease in Brazil, along with the serological detection of other respiratory viruses. We concluded that HoBi-like pestivirus should be considered as part of the BRDC, as a differential diagnosis, to take correct measures of control and prophylaxis.

Pathological and virological features of skin lesions caused by BVDV in cattle.

Dermatitis might occur in mucosal disease (MD) caused by bovine viral diarrhea virus (BVDV). This study describes the pathological and virological features of skin lesions associated with BVDV infection in four persistently infected (PI) cattle. Skin samples were reprocessed for histopathology and IHC. BVDV isolates were obtained and were genetically characterized. In addition to upper alimentary system ulcerative lesions, all cattle (one outbreak and three individual cases) presented focal crusty and ulcerative lesions affecting the mucocutaneous and skin-horn junctions, interdigital clefts, pastern, and areas surrounding the dewclaws and diffuse thickened skin within 7-20 days of infection. Microscopic analysis revealed parakeratotic hyperkeratosis and single-cell keratinocyte death, accompanied by ballooning degeneration and spongiosis in the epidermis, as well as intraepithelial and subcorneal pustules. IHC showed BVDV antigen in the cytoplasm of keratinocytes undergoing individual cell death. Phylogenetic analysis revealed that the isolates from cattle #1, #2, and #4 belonged to BVDV-1a, whereas that from cattle #3 belonged to BVDV-1d. Cytopathic BVDV was isolated from cattle #2 and #3 (MD), and non-cytopathic BVDV was isolated from cattle #1 and #4. Thus, BVDV infection might cause acute disease, characterized by skin and upper alimentary system ulcerative lesions, in both MD and PI cattle.

High prevalence of persistently infected animals from bovine viral diarrhea in Colombian cattle.

BACKGROUND: Bovine Viral Diarrhea Virus (BVDV) is associated with gastrointestinal, respiratory and reproductive diseases of livestock across the world that causes continuous economic losses in the cattle industry. This virus can establish a persistent infection (PI) in calves after the fetal infection, making BVDV positive catle carriers and primary reservoirs which will constantly transmit the virus to healthy and new-born animals. For this reason, the detection of the PI animals in herds is the first line of prevention of the viral infection. RESULTS: In this study, PI animals were detected in five different regions of Colombia through RT-PCR techniques and confirmed by sequencing. BVDV genotypes were determined using one fragment of the 5'UTR. It was found a 7% BVDV prevalence in animals and 22% in farms; and genotype 1 was identified as a single genotype for all of the samples. All samples were BVDV 1a. CONCLUSION: This is the first report in Colombia with higher prevalence rates compared with other places in the world, turned out to be of great importance for the ranchers, the vaccine producers and animal health control parties.

Respiratory signs, fever and lymphopenia in calves inoculated with Brazilian HoBi-like pestiviruses.

Hobi-like viruses (HobiPeV) comprise a novel, recently classified species of bovine pestiviruses, originally identified in commercial fetal bovine serum of Brazilian origin and, subsequently, isolated from diseased animals in several countries. Although frequently isolated from clinical cases, most HobiPeV isolates failed to reproduce overt disease in cattle upon experimental inoculation. Herein, we describe the outcome of experimental infection of four to six months-old seronegative calves with two Brazilian HobiPeV isolates. Calves inoculated intranasally with isolate SV478/07 developed viremia between days 2 and 9 post-inoculation (pi) and shed virus in nasal secretions up to day 11pi. These animals presented hyperthermia (day 7 to 10-11 pi) and lymphopenia from days 4 to 8pi. Clinically, all four calves developed varied degrees of apathy, anorexia, mild to moderate respiratory signs (nasal secretion, hyperemia), ocular discharge and pasty diarrhea in the days following virus inoculation. In contrast, calves inoculated with isolate SV757/15 presented only hyperthermia (days 3 to 10-11 pi) and lymphopenia (days 4-8 pi), without other apparent clinical signs. In these animals, viremia was detected up to day 9 pi and virus shedding in nasal secretions lasted up to day 12-14 pi. Both groups seroconverted to the inoculated viruses, developing virus neutralizing (VN) titers from 320 to 5120 at day 28pi. These results extend previous findings that experimental infections of calves with HobiPeV are predominantly mild, yet they also indicate that field isolates may differ in their ability to cause disease in susceptible animals.

Complete genome sequences of a cytophatic/noncytophatic pair of bovine viral diarrhea virus subtype 1a viruses.

The complete genome sequences of both biotypes of a pair of bovine viral diarrhea viruses isolated from a bovid affected by mucosal disease were determined by next generation sequencing. The cytopathic virus possessed a 423-base insertion derived from bovine poly ubiquitin in the NS2/3 coding region and one nucleotide change. Both biotypes showed an additional glycosylation site in their N-terminus.

Highlighting priority areas for bovine viral diarrhea control in Italy: A phylogeographic approach.

The prevalence and genetic diversity of bovine viral diarrhea virus (BVDV) in a geographic area are largely influenced by live animal trade and management practices. Despite control and eradication programs currently underway in several European countries, the risk of BVDV spread within and among countries is still present. BVDV-1 is the predominant type circulating in European cattle population. In this study, a phylogeographic analysis was applied to the BVDV-1 highest prevalent subtypes in Italy to reconstruct the origin and spatial-temporal distribution and to trace main viral flows between different locations to highlight priority areas for BVDV control. A comprehensive dataset of BVDV-1b (n = 173) and 1e (n = 172) 5' UTR sequences was analysed, including both novel and published sequences from Italy and from European countries bordering and/or with commercial cattle flows with Italy. A common phylogeographic pattern was observed for BVDV-1b and 1e subtypes: interspersion from multiple Italian areas and European countries was widespread until the end of the last century, whereas significant local clusters were observed starting from 2000. These findings support a continuous viral flow among different areas over long time scales with no evidence of significant geographical structure, while local transmission networks are limited to more recent years. Northern Italy has been confirmed as the area of origin of the main clades of both BVDV subtypes at national level, acting both as a crucial area for introduction and a maintenance source for other areas. Piedmont, Central and Southern Italian regions contributed to limited geographical distribution and local BVDV-1b and 1e persistence. On the whole, priority control measures for BVDV-1b and 1e in Italy should be focused on: i) implementation of BVDV systematic control in all Northern Italian regions to break the viral flow from larger to smaller animal populations; and ii) breaking the dynamics of infections in regions with self-maintenance of BVDV by voluntary control programs.

HoBi-like is the most prevalent ruminant pestivirus in Northeastern Brazil.

The ruminant pestiviral species BVDV-1, BVDV-2 and BDV, along with the putative species HoBi-like, may cause substantial economic losses in cattle, sheep and goats. Brazil's large size, variable biomes and wide range of ruminant animal production within different geographic regions suggest that the presence and prevalence of ruminant pestivirus may differ by regions within Brazil. This study investigated the genetic diversity of ruminant pestiviruses and determined the frequency of active infections within two states of the Northeast Region of Brazil, Maranhão and Rio Grande do Norte. Serum samples from 16,621 cattle and 2,672 small ruminants from 569 different herds residing in this region were tested by RT-PCR followed by DNA sequencing. Seventeen positive cattle were detected (0.1%) from fifteen different herds (2.64%). All isolates were classified as HoBi-like pestiviruses based on phylogenetic analysis. All small ruminant samples tested negative. The findings presented herein suggest that the Northeast Region of Brazil has a uniquely high prevalence of HoBi-like viruses. The increasing reports of HoBi-like viruses detected in cattle in the field suggest that natural infection with these viruses may be more widespread than previously thought. The identification of HoBi-like viruses as the most prevalent type of ruminant pestivirus circulating in the Northeast Region of Brazil indicates the need for both continued monitoring and determination of the extent of economic losses associated with HoBi-like virus infections. In addition, it must be taken into account in the choice of diagnostic tests and in vaccine formulations.

Detection and genetic identification of pestiviruses in Brazilian lots of fetal bovine serum collected from 2006 to 2014 / Detecção e identificação genética de pestivírus em lotes brasileiros de soro fetal bovino coletado de 2006 a 2014

The present study performed a genetic identification of pestiviruses contaminating batches of fetal bovine serum (FBS) produced in Brazil from 2006 to 2014. Seventy-three FBS lots were screened by a RT-PCR targeting the 5'untranslated region (UTR) of the pestivirus genome. Thirty-nine lots (53.4%) were positive for pestivirus RNA and one contained infectious virus. Nucleotide sequencing and phylogenetic analysis of the 5'UTR revealed 34 lots (46.6%) containing RNA of bovine viral diarrhea virus type 1 (BVDV-1), being 23 BVDV-1a (5' UTR identity 90.8-98.7%), eight BVDV-1b (93.9-96.7%) and three BVDV-1d (96.2- 97.6%). Six lots (8.2%) contained BVDV-2 (90.3-100% UTR identity) being two BVDV-2a; three BVDV-2b and one undetermined. Four FBS batches (5.5%) were found contaminated with HoBi-like virus (98.3 to 100%). Five batches (6.8%) contained more than one pestivirus. The high frequency of contamination of FBS with pestivirus RNA reinforce the need for systematic and updated guidelines for monitoring this product to reduce the risk of contamination of biologicals and introduction of contaminating agents into free areas.(AU)

No presente estudo foi realizada a identificação genética de pestivírus contaminantes de lotes de soro fetal bovino (SFB) produzidos no Brasil de 2006 a 2014. Setenta e três lotes de SFB foram testados por RT-PCR para a região 5' não traduzida do genoma dos pestivírus. Trinta e nove lotes (53,4%) foram positivos para RNA de pestivírus e um continha vírus infeccioso. O sequenciamento de nucleotídeos e análise filogenética da região 5'UTR revelou que 34 lotes (46,6%) continham RNA do vírus da diarreia viral bovina tipo 1 (BVDV-1), sendo 23 BVDV-1a (identidade na 5' UTR de 90,8-98,7%), oito BVDV-1b (93,9 a 96,7%) e três BVDV-1d (96,2%-97,6%). Seis lotes (8,2%) continham BVDV-2 (90,3 a 100% de identidade), sendo dois BVDV-2a, três BVDV-2b e um de subgenótipo indeterminado. Quatro lotes de SFB (5,5%) estavam contaminados com o vírus HoBi-like (98,3 a 100%). Cinco lotes (6,8%) continham mais do que um pestivírus. A alta frequência de contaminação de SFB com RNA de pestivírus reforça a necessidade para diretrizes sistemáticas atualizadas para a monitoração deste produto com a finalidade de reduzir a contaminação de produtos biológicos e a introdução de agentes contaminantes em áreas livres.(AU)

Eradication of bovine viral diarrhea virus in Germany-Diversity of subtypes and detection of live-vaccine viruses.

Bovine viral diarrhea (BVD) causes high economic losses in the cattle population worldwide. In Germany, an obligatory control program with detection and removal of persistently infected animals is in force since 2011. For molecular tracing of virus transmission, a comprehensive sequence data base of the currently circulating BVD viruses was established. Partial sequences of 1007 samples collected between 2008 and 2016 were generated. As dominant viruses, subtypes 1b (47.0%) and 1d (26.5%) could be identified with no marked geographic or sampling year effect, a much higher amount of BVDV-2c was detected in 2013 compared to other years, predominantly in Western Germany. In addition, subtypes 1a, 1e, 1f, 1h, 1g, 1k, and 2a were found. Interestingly, besides field-viruses, two different live-vaccine viruses were detected in tissue samples of newborn calves (n=37) whose mothers were immunized during pregnancy.

Evolution of Bovine viral diarrhea virus in Canada from 1997 to 2013.

Bovine viral diarrhea virus (BVDV) is a rapidly evolving, single-stranded RNA virus and a production limiting pathogen of cattle worldwide. 79 viral isolates collected between 1997 and 2013 in Canada were subjected to next-generation sequencing. Bayesian phylogenetics was used to assess the evolution of this virus. A mean substitution rate of 1.4×10-3 substitutions/site/year was found across both BVDV1 and BVDV2. Evolutionary rates in the E2 gene were slightly faster than other regions. We also identified population structures below the sub-genotype level that likely have phenotypic implications. Two distinct clusters within BVDV2a are present and can be differentiated, in part, by a tyrosine to isoleucine mutation at position 963 in the E2 protein, a position implicated in the antigenicity of BVDV1 isolates. Distinct clustering within all sub-genotypes, particularly BVDV2a, is apparent and could lead to new levels of genotypic classification. Continuous monitoring of emerging variants is therefore necessary.

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.