Differences in experimental virulence of bovine viral diarrhoea viral strains isolated from haemorrhagic syndromes

Pathogenicity assessment of a bovine viral diarrhea virus type 1l (BVDV-1l) strain in experimentally infected calves

Bovine viral diarrhea is a widespread and economically important viral disease for livestock which can cause clinically diverse manifestations. The number of established BVDV subgenotypes has increased, not only the serological relationships of recently described subgenotypes but virulence and pathogenic characteristics have not yet been mostly elaborated. The dominant BVDV subgenotype in Turkiye was elaborated to be BVDV-1l, that involves more than half of field strains and there is no scientific data to identify the pathogenicity of this strain so far. This study investigated the pathogenicity of a selected field strain (TR-72) from subgenotype BVDV-1l. Experimental infection was implemented by intranasal inoculation of the strain TR-72 (10 ×105.5) to four young calves which were previously not vaccinated and were free both for BVDV antibodies and antigens. Clinical changes as well as blood parameters, body temperature, and viremia were monitored for 14 days. Only mild clinical signs associated with respiratory signs of BVDV infection were observed. Detected clinical signs included nasal discharge, conjunctivitis, cough, fatigue, high rectal temperature reaching 40.7 ℃, and white blood cell counts depression started from the 2nd day and 40.4% decreased between the 12th and 14th days post-infection (poi). The presence of viremia was investigated by virus isolation, RT-PCR, and real-time RT-PCR from blood samples. The efficiency of experimental infection was established not only by observed clinical signs but also by virus isolation from blood leukocytes between the 5th and 8th days poi., virus detection was obtained by real-time PCR between the 3rd - 13th days poi. Besides, the recorded mild clinical signs, high fever, long duration of viremia , and high decrease in blood parameters obtained in this study, it was shown that the noncytopathogenic BVDV-1l strain TR-72 has a moderate virulence in naïve cattle.

In Vitro and In Vivo Characterization of a Typical and a High Pathogenic Bovine Viral Diarrhea Virus Type II Strains

Non-cytopathic (ncp) type 2 bovine viral diarrhea virus (BVDV-2) is widely prevalent in Argentina causing high mortality rates in cattle herds. In this study, we characterized an Argentinean ncp BVDV-2 field isolate (98-124) compared to a high-virulence reference strain (NY-93), using in silico analysis, in vitro assays, and in vivo infections of colostrum-deprived calves (CDC) to compare pathogenic characters and virulence. In vitro infection of bovine peripheral blood mononuclear cells (PBMC) with BVDV 98-124 induced necrosis shortly after infection while NY-93 strain increased the apoptotic rate in infected cells. Experimental infection of CDC (n = 4 each) with these strains caused an enteric syndrome. High pyrexia was detected in both groups. Viremia and shedding were more prolonged in the CDC infected with the NY-93 strain. In addition, NY-93 infection elicited a severe lymphopenia that lasted for 14 days, whereas 98-124 strain reduced the leukocyte counts for 5 days. All infected animals had a diminished lymphoproliferation activity in response to a mitogen. Neutralizing and anti-NS3 antibodies were detected 3 weeks after infection in all infected calves. Virulence was associated with a more severe clinical score, prolonged immune-suppression, and a greater window for transmission. Studies of apoptosis/necrosis performed after in vitro PBMC infection also revealed differences between both strains that might be correlated to the in vivo pathogenesis. Our results identified 98-124 as a low-virulence strain.

Noncytopathic bovine viral diarrhea virus 2 impairs virus control in a mouse model

Bovine viral diarrhea virus (BVDV) is an economically important pathogen that causes development of mild to severe clinical signs in wild and domesticated ruminants. We previously showed that mice could be infected by BVDV. In the present study, we infected mice intraperitoneally with non-cytopathic (ncp) BVDV1 or ncp BVDV2, harvested the blood and organs of the infected mice at days 4, 7, 10 and 14 postinfection (pi), and performed immunohistochemical analyses to confirm BVDV infection. Viral antigens were detected in the spleens of all infected mice from days 4 through 14 and were also found in the mesenteric lymph nodes, gut-associated lymphoid tissue (GALT), heart, kidney, intestine, and bronchus-associated lymphoid tissue (BALT) of some infected mice. In ncp BVDV2-infected mice, flow cytometric analysis revealed markedly fewer CD4(+) and CD8(+) T lymphocytes and lower expression of costimulatory molecules CD80 (B7-1) and CD86 (B7-2) and major histocompatibility complex (MHC) class II (I-A/I-E) than those in ncp BVDV1-infected mice. Production of the cytokines interleukin (IL)-6 and monocyte chemotactic protein (MCP)-1 was higher in the plasma of ncp BVDV2-infected mice than that in that of ncp BVDV1-infected mice. Our results demonstrate that ncp BVDV1 and ncp BVDV2 interact differently with the host innate immune response in vivo. These findings highlight an important distinction between ncp BVDV1 and ncp BVDV2 and suggest that ncp BVDV2 impairs the host's ability to control the infection and enhances virus dissemination.

A bovine viral diarrhea virus type 1a strain in China: isolation, identification, and experimental infection in calves

Background

Bovine viral diarrhea virus (BVDV) is one of the most important pathogens in cattle. Previously, BVDV sub-genotypes of 1b, 1c, 1d, and 1 m were detected in China. However, isolation of BVDV type 1a from cattle has not been reported in China. In 2010, twenty nasal swabs and blood samples were collected from the cattle suspected BVDV infection in Henan province, China. A BVDV isolate was isolated using cell culture, and the pathogenesis of the virus isolate was studied.

Methods

Virus isolation was performed on MDBK cells. The virus identification was conducted by RT-PCR, neutralization test and immunofluorescence assay. In order to determine the genotype of the newly isolated virus, the 5′ un-translated region (5′UTR) of the virus isolate was cloned, sequenced and phylogenetically analyzed. To evaluate the virulence of the virus isolate, four BVDV sero-negative calves were intranasally inoculated with the virus suspension. Rectal temperatures and clinical signs were recorded daily. Blood samples were analyzed for changes in white blood cell counts, and tissue samples were taken for histopathology analysis.

Results

A new isolate of bovine viral diarrhea virus (BVDV), named HN01, was isolated from the nasal swabs using MDBK cell culture. The HN01 strain caused cytopathic effect (CPE) in MDBK cell cultures after two passages. The virus specifically reacted to BVDV1-specific monoclonal antibody in an immunofluorescence assay. A fragment of 288 bp of genome from this isolate was amplified by the RT-PCR. Phylogenetic analysis of 5′UTR indicated that the virus was BVDV 1a. In the pathogenesis study, four calves experimentally infected with the BVDV strain developed depression, cough and other clinical signs. Calves showed high temperature over 40°C, and white blood cell counts dropped more than 40%.

Conclusions

A new subgenotype 1a strain of BVDV was firstly isolated from dairy cattle in China. The experimental infection showed that the virus was moderate pathogenic to cattle and can be used as a BVDV challenge virus to evaluate the efficacy of BVDV vaccines in the target animals.

Experimental infection of cattle, sheep and pigs with 'Hobi'-like pestivirus

To date, limited information is available on the ability of 'Hobi'-like pestiviruses (putative bovine viral diarrhoea 3) to infect and cause disease in animal species traditionally affected by pestiviruses. In order to obtain new insights into host range and pathogenic potential of this atypical pestivirus, BVDV-seronegative calves (n=5), lambs (n=5) and piglets (n=5) were experimentally infected with the European 'Hobi'-like strain Italy-1/10-1, whereas two animals per species served as uninfected controls. Appearance of clinical signs, leukopenia, viremia, viral shedding and seroconversion were monitored for 28 days post-infection. Calves and lambs were successfully infected, displaying respiratory signs (nasal discharge), moderate hyperthermia and leukopenia, viremia and viral shedding through the nasal and faecal routes. Antibody responses were observed in both animal species by ELISA and virus neutralisation assays. In contrast, inoculated piglets did not display any clinical signs nor leukopenia and viral RNA was not detected in any biological samples. Nevertheless, the presence of detectable antibodies by virus neutralisation accounted for a successful, albeit limited infection of these animals.

Haemorrhagic diathesis in neonatal calves: an emerging syndrome in Europe

In 2008 and 2009 a large number of cases of haemorrhagic diathesis (HD) in neonatal calves were reported in different European countries. In Flanders, 84 cases of neonatal HD in 30 herds were reported in this period. The disease typically affects calves younger than 1 month old from different breed and gender. Prominent clinical signs are cutaneous bleeding, petechiae on all mucosae, melena and often high fever. Early in the disease, the mental state of the animals is uncompromised. The typical haematological finding is pancytopenia, with severe to complete thrombocytopenia being the cause of the increased susceptibility to bleeding. In seven of the affected herds blood samples of calves of the same age group as the clinical case were collected and on six of those farms at least one subclinical case could be identified. Necropsy findings were generalized petechiae, ecchymoses or haemorrhages and variable lymphadenopathy. Histopathology of haemorrhagic lesions revealed multifocal extravasation of red blood cells (haemorrhage) with preservation of tissue architecture and absence of other abnormalities. Total bone marrow aplasia and depletion of all lymphoid tissue was the most prominent finding on histology. Activated macrophages and haemophagocytosis were seen on bone marrow cytology from two live calves. Polymerase chain reaction for bovine viral diarrhoea virus, bluetongue and epizootic haemorrhagic disease virus was negative. Several attempts to isolate a viral agent were unsuccessful.

An Outbreak of Late-Term Abortions, Premature Births, and Congenital Deformities Associated with a Bovine Viral Diarrhea Virus 1 Subtype b that Induces Thrombocytopenia

Bovine viral diarrhea virus 1 (BVDV-1) subtype b was isolated from premature Holstein calves from a dairy herd that experienced an outbreak of premature births, late-term abortions, brachygnathism, growth retardation, malformations of the brain and cranium, and rare extracranial skeletal malformations in calves born to first-calf heifers. Experimental inoculation of 3 colostrum-deprived calves aged 2–4 months old with this BVDV isolate resulted in thrombocytopenia, lymphopenia, and leukopenia. Outbreaks of brachygnathism are rarely associated with BVDV, and thrombocytopenia is rarely associated with BVDV-1 strains.

Sequence-optimised E2 constructs from BVDV-1b and BVDV-2 for DNA immunisation in cattle

We report DNA immunisation experiments in cattle using plasmid constructs that encoded glycoprotein E2 from bovine viral diarrhoea virus (BVDV)-1 (E2.1) and BVDV-2 (E2.2). The coding sequences were optimised for efficient expression in mammalian cells. A modified leader peptide sequence from protein gD of BoHV1 was inserted upstream of the E2 coding sequences for efficient membrane export of the proteins. Recombinant E2 were efficiently expressed in COS7 cells and they presented the native viral epitopes as judged by differential recognition by antisera from cattle infected with BVDV-1 or BVDV-2. Inoculation of pooled plasmid DNA in young cattle elicited antibodies capable of neutralising viral strains representing the major circulating BVDV genotypes.

Risk assessment of transmission of bovine viral diarrhea virus (BVDV) in abattoir-derived in vitro produced embryos

Bovine virus diarrhea virus (BVDV) is a pathogen of the bovine reproductive system causing reduced conception rates, abortions and persistently infected calves. Most if not all strains of BVDV are transmissible by natural mating and AI. For international trade, it is recommended that in vitro fertilized embryos be washed according to the IETS Manual. However, BVDV may not be entirely washed out, resulting in possible transmission risks to recipients. Donor cows, donor bulls and biological agents are all possible sources of contamination. The process for producing in vitro produced (IVP) embryos is complex and non-standard, and some procedures can contribute to spread of BVDV to uninfected embryos. The structure of the zone pellucida (ZP) of IVP embryos permits adherence of BVDV to the ZP. To estimate the risk of producing infected recipients and persistently infected calves from abattoir-derived IVP embryos, a quantitative risk assessment model using Microsoft Excel and Palisade @Risk was developed. Assumptions simplified some of the complexities of the IVP process. Uncertainties due to incomplete or variable data were addressed by incorporating probability distributions in the model. Model variables included: disease prevalence; the number of donor cows slaughtered for ovaries; the number of oocytes collected, selected and cultured; the BVDV status of ovaries, semen, biological compounds and its behavior in the IVP embryo process. The model used the Monte Carlo method to simulate the IVP process. When co-culture cells derived from donor cows of unknown health status were used for in vitro culture (IVC), the probability of a recipient cow at risk of infection to BVDV per oocyte selected for IVP processing averaged 0.0006. However, when co-culture free from BVDV was used, the probability was 1.2 x 10(-5). Thus, for safe international trade in bovine IVP embryos (i.e. negligible risks of transmission of BVDV), co-culture cells, if used during IVC for producing IVP embryos, should be disease-free.

Origination and consequences of bovine viral diarrhea virus diversity

The potential consequences of BVDV genetic and antigenic diversity are far ranging. The complexity of clinical presentations associated with BVDV likely arises from factors encoded by the virus genome. More importantly,prevention and control of BVDV may be complicated by diagnostic and immunization failure resulting from virus diversity. Evolutionary pressures will continue to drive further diversity, making control of BVDV challenging. Current and the potential for future BVDV strain diversity should be considered when designing BVDV control programs both at the individual farm and national herd level.

Bovine viral diarrhea virus genomic associations in mucosal disease, enteritis and generalized dermatitis outbreaks in Argentina

The objective of the present work is the description outbreaks caused by bovine viral diarrhea virus (BVDV) in commercial beef cattle ranches in Argentina. Genetic affiliation and their association with the clinical manifestation were carried out with five BVDV isolates from an outbreak of mucosal disease (MD) (Outbreak #1), acute enteritis (Outbreaks #2 and #3) and generalized dermatitis (Outbreaks #4 and #5). Upon genetic analysis CP BVDV isolate of Outbreak #1 clustered to closely to BVDV Oregon (Genotype 1). BVDV isolates from the outbreaks of generalized dermatitis (Outbreaks #4 and #5) were located close to BVDV Osloss within Genotype 1. The identification by immunohistochemistry of BVDV in exudative dermatitis indicates the epithelial cell tropism of the virus. Phylogenic characterization of BVDV from Outbreaks #2 and #3 locate them as BVDV-2. 5'UTR sequence of these viruses revealed a homology of 88 and 90% to BVDV-890 (Genotype 2) and a 77 and 75% to BVDV-SD1 (Genotype 1), respectively. The association of BVDV-2 with severe disease indicates the presence of highly virulent strains. Data from natural outbreaks where BVDV-1 and BVDV-2 were isolated revealed that pathology overlaps and not clearly allows the differentiation between genotypes based on gross or microscopic lesions. Thus, for a definitive diagnosis, further virology and molecular studies are necessary. Additionally, the results of this work focused on the origin and consequences of genetic variations of BVDV with regard to pathogenesis and suggest the association between genotype and a defined clinical syndrome.

Assessment of the clinical and virological protection provided by a commercial inactivated bovine viral diarrhoea virus genotype 1 vaccine against a BVDV genotype 2 challenge

A new genotype of bovine viral diarrhoea virus (BVDV), designated BVDV-2, has emerged in the last decade and in recent years the prevalence of BVDV-2 strains has increased. A vaccination-challenge study was carried out to determine the cross-protective efficacy of a commercial inactivated vaccine containing a BVDV-1 strain. A group of five BVDV-free calves was vaccinated twice and a second group of five calves served as negative controls. Two months after the first vaccination, all the calves were challenged intranasally with BVDV-2 strain BVD890. The clinical signs of disease, the changes in haematological variables and the level of viraemia were significantly less in the vaccinated group.

Distribution of viral antigen and development of lesions after experimental infection of calves with a BVDV 2 strain of low virulence

To examine the virus-host interaction in subclinical bovine viral diarrhea virus (BVDV) infections, the spread of a BVDV 2 strain of low virulence to different organs and the development of lesions were investigated. Eight colostrum-deprived, clinically healthy, 2-3-month-old calves were intranasally inoculated with 10(6) tissue culture infective dose of the naturally occurring BVDV 2 strain 28508-5 of low virulence, and 2 served as controls. Two calves each were euthanized at days 3, 6, 9, and 13 postinoculation (pi). Representative tissues were processed for histology and immunohistology. Signs of overt clinical disease were absent. However, a mild temperature elevation at days 7 or 8 pi and a moderate decrease of circulating lymphocytes occurred in all inoculated calves. The BVDV antigen was detected at day 3 pi in several lymphoid tissues. At day 6 pi, BVDV antigen was found widespread in lymphoid tissues and multifocally in intestinal epithelial cells but was associated with no or subtle lesions only. At day 9 pi, much less BVDV antigen was detectable, but there was severe depletion of lymphoid tissues. At day 13 pi, BVDV antigen had been cleared from most lymphoid tissues that were at variable phases of depletion and recovery. In conclusion, the BVDV strain of low virulence spread to lymphoid tissues and intestinal epithelial cells but was rapidly eliminated. Transient depletion of lymphoid tissues was followed by recovery.

Genetic diversity of ruminant pestiviruses from Spain

The genetic diversity of ruminant pestiviruses from Spain was investigated by sequencing analysis of the 5' non-coding region (5'NCR) from 10 ovine and 41 bovine samples collected along 4 years (1999-2002) from different farms. The 5'NCR amplicons generated by a one-tube RT-PCR using primers 324/326 were sequenced and phylogenetically analyzed. When compared with strains from GenBank database, Spanish viruses clustered into three genotypes: BVDV 1, BDV and CSFV. No BVDV 2 strains were identified. The 41 bovine samples were all BVDV 1 genotype, but they were further subdivided into subgroups 1b (35) and 1e (6). There was no apparent association between the genotype and clinical symptoms, or the geographic area of origin. However, subgroup 1e has been recently described for isolates from France and, interestingly, subgroup 1e viruses were collected from areas close to the French border. Nine of the ten ovine samples formed a tight cluster within BDV type but clearly differed from BDV subgroups A and B sustaining the need to define a new subgroup as BDV-C in which these ovine strains would be included. Finally, although further studies are needed, the grouping of an ovine sample with CSFV strains would be the first description of a CSFV genotype for ovine pestiviruses.

Distribution of viral antigen and development of lesions after experimental infection with highly virulent bovine viral diarrhea virus type 2 in calves

OBJECTIVE

To correlate tissue distribution with development of lesions after experimental infection with a virulent strain of noncytopathic bovine viral diarrhea virus (BVDV) type 2 in calves.

ANIMALS

Ten 14-day-old and two 2-month-old colostrum-deprived calves.

PROCEDURE

Calves were intranasally inoculated with BVDV type-2 strain 1373 from an outbreak of clinically severe bovine viral diarrhea (BVD). Two 14-day-old calves served as noninfected controls. Two calves each were euthanatized on postinoculation days 3, 6, and 12, and 1 each on days 8, 9, 13, and 14. Tissues were collected for immunohistologic and histologic examination.

RESULTS

Inoculated calves developed nonspecific clinical signs characterized by high fever and decreased numbers of leukocytes and thrombocytes. Viral antigen was detected focally in lymphoid tissues on day 3. On days 6, 8, 9, 12, and 14, viral antigen became increasingly widespread throughout organs and tissues. Viral antigen in lymphoid tissues was associated with severe depletion of all compartments. Lesions in other tissues were not well correlated with distribution of viral antigen. Depletion of lymphoid tissues was observed in a calf on day 13, but viral antigen had been cleared from most tissues and was detected in vascular walls only.

CONCLUSIONS AND CLINICAL RELEVANCE

Infection with a virulent BVDV strain resulted in wide dissemination of viral antigen in host tissues. Severe lymphoid depletion developed in lymphoid tissues, whereas viral antigen was generally not associated with lesions in other tissues. Findings suggest that development of lesions in acute BVD is not solely a function of viral replication and is also attributable to host reaction to infection.

Recovery of virulent and RNase-negative attenuated type 2 bovine viral diarrhea viruses from infectious cDNA clones

Cloned cDNA derived from the genome of the virulent type 2 bovine viral diarrhea virus (BVDV) strain NY'93/C was sequenced and served for establishment of the infectious cDNA clone pKANE40A. Virus recovered from pKANE40A exhibited growth characteristics similar to those of wild-type BVDV NY'93/C and proved to be clinically indistinguishable from the wild-type virus in animal experiments. A virus mutant in which the RNase residing in the viral glycoprotein E(rns) was inactivated, revealed an attenuated phenotype. The plasmid pKANE40A represents the first infectious cDNA clone established for a type 2 BVDV and offers a variety of new approaches to analyze the mechanisms of BVDV-induced disease in cattle.

Genetic and antigenic variability in bovine viral diarrhea virus (BVDV) isolates from Belgium

This report describes the genetic and antigenic variability of bovine viral diarrhea virus strains isolated in Belgium. Part of the 5' untranslated region and the 5' end of the gp53 (E2) coding sequence were amplified by PCR and sequenced. Phylogenetic analysis showed that most field isolates segregated into genotypes Ib or II. Only one out of 28 field isolates belonged to genotype Ia. Interestingly, some type I strains were equally divergent from types Ia and Ib strains and clustered into additional subtypes within genotype I. Immune sera from young calves experimentally inoculated with field isolates first identified on the basis of their sequences were used in two-way neutralisation experiments. The results clearly differentiated type I from type II strains although some degree of cross-neutralisation was observed. Within type I, the new clusters could not be antigenically differentiated from the more prevalent type Ib strains or from type Ia strain NADL, suggesting that BVDV genotype I is antigenically homogeneous. The isolation of BVDV types I and II strains from cell lines and from a bovine vaccine suggest that molecular epidemiology surveillance is warranted for BVDV.

Phylogenetic analysis of the 5'-untranslated region of german BVDV type II isolates

On the basis of genetic differences, bovine viral diarrhoea viruses (BVDV) are subclassified into two distinct genotypes, BVDV type I and BVDV type II. We selected German BVDV type II isolates using the BVDV type I-specific monoclonal antibody WB160 and flow cytometric analysis for further characterization. For molecular characterization, a 288-bp fragment of the 5'-untranslated region (5'-UTR) of the selected isolates was investigated by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing. Sequence comparisons of the partial 5'-UTR sequences and their phylogenetic analyses demonstrated that the 18 German BVDV type II isolates all belong to either subtype IIa (10 isolates) or subtype IIc (eight isolates). Nevertheless, the German BVDV type II isolates were genetically different (89.9-94.3% sequence identity) from the standard BVDV type II strain 890 from North America, which was recently classified as BVDV type IIa. Furthermore, a clear subdivision of the German BVDV type II isolates into two distinct subtypes (BVDV IIa Germany and BVDV IIc Germany) is shown. Viruses of both subgroups differed in the analysed 5'-UTR fragment from each other (91.6-95.2% sequence identity), but were highly conserved within the same German subtype (97.2-100% sequence identity). These findings are discussed in the context of BVDV type II origin, possible introduction into Germany, its epidemiology and impact for vaccine development.

Virus neutralising antibodies against 22 bovine viral diarrhoea virus isolates in vaccinated calves

Seven of nine colostrum deprived calves, free from bovine viral diarrhoea virus (BVDV), were vaccinated with a commercially available vaccine containing two inactivated strains of BVDV, an inactivated strain of bovine herpesvirus-1 and modified-live strains of bovine respiratory syncytial virus and para-influenza-3 virus. The two other calves were kept as controls. The virus neutralising (VN) antibodies induced by vaccination were tested against 22 antigenically diverse BVDV isolates, including reference strains and field isolates, both cytopathic and non-cytopathic, as well as genotypes I and II. The strains were isolated in Belgium, France, Germany, the United Kingdom and the USA. While there were variations in the VN titres of the individual calves against all the strains, serum from the seven animals neutralised 20 or more of the strains tested. From the results, it can be concluded that the vaccine can stimulate the production of VN antibodies capable of neutralising a wide range of European and American isolates of BVDV, including genotypes I and II.

Prevalence of genotypes 1 and 2 of bovine viral diarrhea virus in Lower Saxony, Germany

The aim of this study was to find whether an antigenic drift had occurred in Lower Saxony in the past 40 years. For this, the genetic diversity of bovine viral diarrhea virus (BVDV) isolates mainly from Lower Saxony was estimated by RT-PCR and sequencing of a 420 bp fragment of the E2 glycoprotein gene. Sixty-one field virus isolates collected during routine diagnostics between 1960 and 2000 in Lower Saxony, Northern Germany, were analyzed. Phylogenetic analysis allowed discrimination of genotypes BVDV 1 and 2. Excepting two isolates, which were of BVDV type 2, most of the isolates were classified as BVDV type 1. This group could be further subdivided into four subgroups and one disparate isolate. Independent of the year of isolation and geographical localization, 54 isolates clustered in two subtypes (BVDV subtypes 1b and 1d). Only one isolate was classified as BVDV type 1a, thus being similar to the North American NADL strain, and to the vaccine strain Oregon C24V, which was extensively used for vaccination in Germany. The remaining isolates belonged to new clusters tentatively designated as BVDV subtypes 1g and 1f. To compare the cluster designation with that of other studies, phylogenetic analysis of representatives of each of the subgroups based on the 5' untranslated region (5'UTR) was performed. It grouped the viruses similarly. The results indicate that the BVDV population seems to be relatively stable over 40 years in Lower Saxony.