A genetic predisposition for bovine neonatal pancytopenia is not due to mutations in coagulation factor XI

Three cases of alloimmune mediated pancytopenia in calves resembling bovine neonatal pancytopenia

Background

Between 2007 and 2011 several thousands of calves died from bovine neonatal pancytopenia (BNP), a bleeding syndrome triggered by vaccine induced alloantibodies from the dams. Following withdrawal of the involved bovine viral diarrhoea virus (BVDv) vaccine, the incidence of this condition rapidly decreased, with no reported cases in the last 5 years. Here, we report a recent immune-mediated pancytopenia in three calves from two different suckler herds, clinically indistinguishable from BNP.

Case presentation

Three Belgian Blue suckler calves from two different farms, aged around two weeks, showed multiple bleedings disseminated on the skin and petechiae and ecchymoses on the mucosae. Blood examination confirmed anaemia, leukopenia and thrombocytopenia. BVDv infection was excluded. Despite blood transfusion and cortisone therapy, all three animals died. Necropsy and histology confirmed bone marrow depletion. Binding of IgG from the dams on leukocytes of the calves was demonstrated by flow cytometry. Two calves, originating from the same farm, received colostrum from the same dam. None of the calves were given colostrum replacers or colostrum supplements. No link with the BNP causing BVDv vaccine could be evidenced. However, dams had been vaccinated against bovine herpesvirus 1, parainfluenza-3 virus, bovine respiratory syncytial virus and bluetongue virus serotype 8.

Conclusions

Alloimmune mediated pancytopenia was evidenced in three animals, clinically and pathologically indistinguishable from BNP. Whether this disease is again vaccine mediated remains to be determined.

A Functionally Different Immune Phenotype in Cattle Is Associated With Higher Mastitis Incidence

A novel vaccine against bovine viral diarrhea (BVD) induced pathogenic antibody production in 5-10% of BVD-vaccinated cows. Transfer of these antibodies via colostrum caused Bovine neonatal pancytopenia (BNP) in calves, with a lethality rate of 90%. The exact immunological mechanisms behind the onset of BNP are not fully understood to date. To gain further insight into these mechanisms, we analyzed the immune proteome from alloreactive antibody producers (BNP cows) and non-responders. After in vitro stimulation of peripheral blood derived lymphocytes (PBL), we detected distinctly deviant expression levels of several master regulators of immune responses in BNP cells, pointing to a changed immune phenotype with severe dysregulation of immune response in BNP cows. Interestingly, we also found this response pattern in 22% of non-BVD-vaccinated cows, indicating a genetic predisposition of this immune deviant (ID) phenotype in cattle. We additionally analyzed the functional correlation of the ID phenotype with 10 health parameters and 6 diseases in a retrospective study over 38 months. The significantly increased prevalence of mastitis among ID cows emphasizes the clinical relevance of this deviant immune response and its potential impact on the ability to fight infections.

A novel RNAseq-assisted method for MHC class I genotyping in a non-model species applied to a lethal vaccination-induced alloimmune disease

Background

MHC class I genotyping is essential for a wide range of biomedical, immunological and biodiversity applications. Whereas in human a comprehensive MHC class I allele catalogue is available, respective data in non-model species is scarce in spite of decades of research.

Results

Taking advantage of the new high-throughput RNA sequencing technology (RNAseq), we developed a novel RNAseq-assisted method (RAMHCIT) for MHC class I typing at nucleotide level. RAMHCIT is performed on white blood cells, which highly express MHC class I molecules enabling reliable discovery of new alleles and discrimination of closely related alleles due to the high coverage of alleles with reads. RAMHCIT is more comprehensive than previous methods, because no targeted PCR pre-amplification of MHC loci is necessary, which avoids preselection of alleles as usually encountered, when amplification with MHC class I primers is performed prior to sequencing. In addition to allele identification, RAMHCIT also enables quantification of MHC class I expression at allele level, which was remarkably consistent across individuals.

Conclusions

Successful application of RAMHCIT is demonstrated on a data set from cattle with different phenotype regarding a lethal, vaccination-induced alloimmune disease (bovine neonatal pancytopenia), for which MHC class I alleles had been postulated as causal agents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2688-0) contains supplementary material, which is available to authorized users.

Bovine neonatal pancytopenia (BNP): novel insights into the incidence, vaccination-associated epidemiological factors and a potential genetic predisposition for clinical and subclinical cases

Bovine neonatal pancytopenia (BNP) is a haemorrhagic disease of newborn calves elicited by colostrum from specific cows. Two studies have indicated that BNP-inducing colostrum might be associated with alloantibodies directed against MHC class I in response to vaccination with a distinct inactivated viral vaccine. However, the proportion of alloantibody-producing individuals by far exceeds the proportion of clinical BNP cases in the vaccinated population. This raises the question about the incidence of subclinical, unrecognised cases and also suggests further factors involved in BNP pathogenesis, e.g., genetic predisposition. Our results on neonatal calves from a closely monitored resource population confirmed the hypothesis of a genetic predisposition for clinical BNP and suggest that the predisposition is also involved in subclinical BNP-cases. No indication was obtained for a higher frequency of subclinical BNP-cases compared with clinical cases. Neither time point nor frequency of vaccination was a relevant factor for BNP in our resource population.

Calf-level factors associated with bovine neonatal pancytopenia--a multi-country case-control study

Bovine neonatal pancytopenia (BNP), a high fatality condition causing haemorrhages in calves aged less than 4 weeks, was first reported in 2007 in Germany and subsequently observed at low incidence in other European countries and New Zealand. A multi-country matched case-control study was conducted in 2011 to identify calf-level risk factors for BNP. 405 BNP cases were recruited from 330 farms in Belgium, France, Germany and the Netherlands by laboratory confirmation of farmer-reported cases. Up to four calves of similar age from the same farm were selected as controls (1154 calves). Risk factor data were collected by questionnaire. Multivariable modelling using conditional logistic regression indicated that PregSure®BVD (PregSure, Pfizer Animal Health) vaccination of the dam was strongly associated with BNP cases (adjusted matched Odds Ratio - amOR 17.8 first lactation dams; 95% confidence interval – ci 2.4, 134.4; p = 0.005), and second or more lactation PregSure-vaccinated dams were more likely to have a case than first lactation vaccinated dams (amOR 2.2 second lactation; ci 1.1, 4.3; p = 0.024; amOR 5.3 third or more lactation; ci 2.9, 9.8; p = <0.001). Feeding colostrum from other cows was strongly associated with BNP if the dam was not PregSure-vaccinated (amOR 30.5; ci 2.1, 440.5; p = 0.012), but the effect was less if the dam was PregSure-vaccinated (amOR 2.1; ci 1.1, 4.0; p = 0.024). Feeding exclusively dam’s milk was a higher risk than other types of milk (amOR 3.4; ci 1.6, 7.5; p = 0.002). The population attributable fractions were 0.84 (ci 0.68, 0.92) for PregSure vaccination, 0.13 (ci 0.06, 0.19) for feeding other cows’ colostrum, and 0.15 (ci 0.08, 0.22) for feeding dam’s milk. No other calf-level factors were identified, suggesting that there are other important factors that are outside the scope of this study, such as genetics, which explain why BNP develops in some PregSure-colostrum-exposed calves but not in others.

Reproduction of bovine neonatal pancytopenia (BNP) by feeding pooled colostrum reveals variable alloantibody damage to different haematopoietic lineages

Bovine neonatal pancytopenia (BNP) is a recently described haemorrhagic disease of calves characterised by thrombocytopenia, leucopenia and bone marrow depletion. Feeding colostrum from cows that have previously produced a BNP affected calf has been shown to induce the disease in some calves, leading to the hypothesis that alloantibodies in colostrum from dams of affected calves mediate destruction of blood and bone marrow cells in the recipient calves. The aims of the current experimental study were first to confirm the role of colostrum-derived antibody in mediating the disease and second to investigate the haematopoietic cell lineages and maturation stages depleted by the causative antibodies. Clinical, haematological and pathological changes were examined in 5 calves given a standardised pool of colostrum from known BNP dams, and 5 control calves given an equivalent pool of colostrum from non-BNP dams. All calves fed challenge colostrum showed progressive depletion of bone marrow haematopoietic cells and haematological changes consistent with the development of BNP. Administration of a standardised dose of the same colostrum pool to each calf resulted in a consistent response within the groups, allowing detailed interpretation of the cellular changes not previously described. Analyses of blood and serial bone marrow changes revealed evidence of differential effects on different blood cell lineages. Peripheral blood cell depletion was confined to leucocytes and platelets, while bone marrow damage occurred to the primitive precursors and lineage committed cells of the thrombocyte, lymphocyte and monocyte lineages, but only to the more primitive precursors in the neutrophil, erythrocyte and eosinophil lineages. Such differences between lineages may reflect cell type-dependent differences in levels of expression or conformational nature of the target antigens.

Demonstration of early functional compromise of bone marrow derived hematopoietic progenitor cells during bovine neonatal pancytopenia through in vitro culture of bone marrow biopsies

Background

Bovine neonatal pancytopenia (BNP) is a syndrome characterised by thrombocytopenia associated with marked bone marrow destruction in calves, widely reported since 2007 in several European countries and since 2011 in New Zealand. The disease is epidemiologically associated with the use of an inactivated bovine virus diarrhoea (BVD) vaccine and is currently considered to be caused by absorption of colostral antibody produced by some vaccinated cows (“BNP dams”). Alloantibodies capable of binding to the leukocyte surface have been detected in BNP dams and antibodies recognising bovine MHC class I and β-2-microglobulin have been detected in vaccinated cattle. In this study, calves were challenged with pooled colostrum collected from BNP dams or from non-BNP dams and their bone marrow hematopoietic progenitor cells (HPC) cultured in vitro from sternal biopsies taken at 24 hours and 6 days post-challenge.

Results

Clonogenic assay demonstrated that CFU-GEMM (colony forming unit-granulocyte/erythroid/macrophage/megakaryocyte; pluripotential progenitor cell) colony development was compromised from HPCs harvested as early as 24 hour post-challenge. By 6 days post challenge, HPCs harvested from challenged calves failed to develop CFU-E (erythroid) colonies and the development of both CFU-GEMM and CFU-GM (granulocyte/macrophage) was markedly reduced.

Conclusion

This study suggests that the bone marrow pathology and clinical signs associated with BNP are related to an insult which compromises the pluripotential progenitor cell within the first 24 hours of life but that this does not initially include all cell types.

Factors associated with bovine neonatal pancytopenia (BNP) in calves: a case-control study

Bovine neonatal pancytopenia (BNP; previously known as idiopathic haemorrhagic diathesis and commonly known as bleeding calf syndrome) is a novel haemorrhagic disease of young calves which has emerged in a number of European countries during recent years. Data were retrospectively collected during June to November 2010 for 56 case calves diagnosed with BNP between 17 March and 7 June of the same year. These were compared with 58 control calves randomly recruited from herds with no history of BNP. Multivariable logistic regression analysis showed that increased odds of a calf being a BNP case were associated with its dam having received PregSure® BVD (Pfizer Animal Health) vaccination prior to the birth of the calf (odds ratio (OR) 40.78, p<0.001) and its herd of origin being located in Scotland (OR 9.71, p = 0.006). Decreased odds of a calf being a BNP case were associated with the calf having been kept outside (OR 0.11, p = 0.006). The longer that a cattle herd had been established on the farm was also associated with decreased odds of a calf in that herd being a BNP case (OR 0.97, p = 0.011).

Vaccine-induced antibodies linked to bovine neonatal pancytopenia (BNP) recognize cattle major histocompatibility complex class I (MHC I)

A mysterious disease affecting calves, named bovine neonatal pancytopenia (BNP), emerged in 2007 in several European countries. Epidemiological studies revealed a connection between BNP and vaccination with an inactivated vaccine against bovine virus diarrhea (BVD). Alloantibodies reacting with blood leukocytes of calves were detected in serum and colostrum of dams, which have given birth to calves affected by BNP. To understand the linkage between vaccination and the development of alloantibodies, we determined the antigens reacting with these alloantibodies. Immunoprecipitation of surface proteins from bovine leukocytes and kidney cells using sera from dams with a confirmed case of BNP in their gestation history reacted with two dominant protein species of 44 and 12 kDa. These proteins were not detected by sera from dams, free of BVDV and not vaccinated against BVD, and from sera of animals vaccinated with a different inactivated BVD vaccine. The 44 kDa protein was identified by mass spectrometry analysis as MHC I, the other as β-2-microglobulin. The presence of major histocompatibility complex class I (MHC I) in the vaccine was confirmed by Western blot using a MHC I specific monoclonal antibody. A model of BNP pathogenesis is proposed.