Anti-idiotypic antibodies mimic bovine viral diarrhea virus antigen

Arrhythmias after COVID-19 Vaccination: Have We Left All Stones Unturned?

SARS-CoV-2 vaccination offered the opportunity to emerge from the pandemic and, thereby, worldwide health, social, and economic disasters. However, in addition to efficacy, safety is an important issue for any vaccine. The mRNA-based vaccine platform is considered to be safe, but side effects are being reported more frequently as more and more people around the world become treated. Myopericarditis is the major, but not the only cardiovascular complication of this vaccine; hence it is important not to underestimate other side effects. We report a case series of patients affected by cardiac arrhythmias post-mRNA vaccine from our clinical practice and the literature. Reviewing the official vigilance database, we found that heart rhythm disorders after COVID vaccination are not uncommon and deserve more clinical and scientific attention. Since the COVID vaccine is the only vaccination related to this side effect, questions arose about whether these vaccines could affect heart conduction. Although the risk-benefit ratio is clearly in favor of vaccination, heart rhythm disorders are not a negligible issue, and there are red flags in the literature about the risk of post-vaccination malignant arrhythmias in some predisposed patients. In light of these findings, we reviewed the potential molecular pathways for the COVID vaccine to impact cardiac electrophysiology and cause heart rhythm disorders.

CD46 is a cellular receptor for bovine viral diarrhea virus

Various monoclonal antibodies (MAbs) that recognize cell surface proteins on bovine cells were previously shown to efficiently block infection with bovine viral diarrhea virus (BVDV) (C. Schelp, I. Greiser-Wilke, G. Wolf, M. Beer, V. Moennig, and B. Liess, Arch. Virol. 140:1997-2009, 1995). With one of these MAbs, a 50- to 58-kDa protein was purified from calf thymus by immunoaffinity chromatography. Microchemical analysis of two internal peptides revealed significant sequence homology to porcine and human CD46. The cDNA of bovine CD46 (CD46(bov)) was cloned and further characterized. Heterologously expressed CD46(bov) was detected by the MAb used for purification. A putative function of CD46(bov) as a BVDV receptor was studied with respect to virus binding and susceptibility of nonpermissive cells. While the expression of CD46(bov) correlated well with the binding of [(3)H]uridine-labeled BVDV, the susceptibility of cells nonpermissive for BVDV was not observed. However, the expression of CD46(bov) resulted in a significant increase in the susceptibility of porcine cells to BVDV. These results provide strong evidence that CD46(bov) serves as a cellular receptor for BVDV.

Characterization of a putative receptor protein for bovine viral diarrhea virus

In a previous communication, we reported a 50-kDa cell surface protein from Madin-Darby bovine kidney (MDBK) cells as a putative receptor for bovine viral diarrhea virus (BVDV). The present study delineates further characterization of the receptor protein. Protease treatment of cultured MDBK cells adversely affected the receptor, thus abolishing the binding of anti-D89 (BVDV anti-idiotypes) to the cells. However, pretreatment of the cells with either phospholipases or glycosidases did not significantly change the anti-D89 binding to the cells. Additionally, pretreatment of cell monolayers with proteases decreased BVDV attachment and replication in the cells. These results suggested that the receptor for BVDV is a protein in nature, and glycosylation and phosphorylation may not play a direct role in BVDV attachment to cells. The BVDV receptor gradually regenerated on the cell surface after the protease-treated cells were cultured in normal growth medium. Regeneration of the BVDV receptor to a normal level took about 4 h as indicated by flow cytometric analysis and this process was inhibited in the presence of cycloheximide, a protein synthesis inhibitor. The 50-kDa receptor protein purified by electro-elution inhibited BVDV infection in a plaque reduction assay. It also inhibited anti-D89 binding to cells as analyzed by flow cytometry. These data demonstrated the nature of the 50-kDa protein as a specific receptor for BVDV.

A 50 kDa membrane protein from bovine kidney cells is a putative receptor for bovine viral diarrhea virus (BVDV)

A 50 kDa cell surface protein from MDBK cells has been identified as a putative receptor for bovine viral diarrhea virus (BVDV) by using a BVDV specific anti-idiotypic antibody (Anti-D89). This study delineates further characterization of the receptor protein. Protease treatment of cultured MDBK cells adversely affected the receptor thus abolishing the binding of anti-D89 to the cells. However, pretreatment of the cells with either phospholipases or glycosidases did not signficantly alter the extent of anti-D89 binding. Additionally, pretreatment of cell monolayers with proteases decreased BVDV attachment and replication in the cells. These results suggested that the receptor for BVDV is a protein in nature, and glycosylation and phosphorylation of the receptor protein may not play a direct role in BVDV attachment to cells. The BVDV receptor protein gradually regenerated on cells when they were maintained in culture following protease treatment. The purified 50 kDa receptor protein also significantly inhibited BVDV infection in a plaque reduction assay.

Anti-idiotypic antibodies mimicking glycoprotein D of herpes simplex virus identify a cellular protein required for virus spread from cell to cell and virus-induced polykaryocytosis

Glycoprotein D (gD) of herpes simplex virus 1 (HSV-1) is required for stable attachment and penetration of the virus into susceptible cells after initial binding. We derived anti-idiotypic antibodies to the neutralizing monoclonal antibody HD1 to gD of HSV-1. These antibodies have the properties expected of antibodies against a gD receptor. Specifically, they bind to the surface of HEp-2, Vero, and HeLa cells susceptible to HSV infection and specifically react with a Mr 62,000 protein in these and other (143TK- and BHK) cell lines. They neutralize virion infectivity, drastically decrease plaque formation by impairing cell-to-cell spread of virions, and reduce polykaryocytosis induced by strain HFEM, which carries a syncytial (syn-) mutation. They do not affect HSV growth in a single-step cycle and plaque formation by an unrelated virus, indicating that they specifically affect the interaction of HSV gD) with a cell surface receptor. We conclude that the Mr 62,000 cell surface protein interacts with gD to enable spread of HSV-1 from cell to cell and virus-induced polykaryocytosis.

Identification of bovine viral diarrhea virus receptor in different cell types

Anti-idiotypic antibodies (anti-ids) have been used successfully in studies on bovine viral diarrhea virus (BVDV) receptor(s) in our laboratory. The anti-ids specifically bound to cultured cells and identified a 50 kDa cellular membrane protein, which is thought to be a specific receptor for BVDV. In this study, flow cytometric analyses demonstrated that the anti-ids also specifically bound to different cell types, namely MDBK, EBK, BT, PK15, MA1O4, and Vero. Experiments on virus attachment and replication showed that BVDV adsorbed to all cells and replicated in them except monkey kidney cells MA 104 and Vero (non-permissive). Results from plaque reduction assays indicated that cellular membrane proteins from all cell lines competitively inhibited BVDV attachment to cultured MDBK cells, suggesting the presence of BVDV receptor on all cells. Immunoblotting of cell membrane proteins with the anti-ids revealed a 50 kDa protein in both permissive and nonpermissive cells. Subcloned or synchronized MDBK cells demonstrated no significant difference of binding with anti-ids as compared to normal cultured cells.

Control of bovine viral diarrhea infection by use of vaccination

Vaccination with either inactivated or modified live virus vaccines is beneficial for control of BVD in cattle. The advantages and/or disadvantages of each type of vaccine often influence vaccine selection. The frequency of vaccination depends on the herd management system, regional prevalence of BVDV, and required duration of protection. Vaccines for BVD likely will change in content as knowledge of BVDV increases and as new technologies are adapted for vaccine production.

Antigenic differences between a field isolate and vaccine strains of bovine viral diarrhea virus

Antigenic diversity among the bovine viral diarrhea virus (BVDV) cytopathic strains 87-2552 (field isolate) and NADL and Singer (prototype strains) was demonstrated with monoclonal antibodies (MAbs) in enzyme-linked immunosorbent, immunofluorescence, virus neutralization, and immunoprecipitation assays. Two MAbs against BVDV strain 87-2552, designated D11 and B7, strongly neutralized this field strain and were specific for the 48-kDa glycoprotein of the virus. These two MAbs have different subisotypes, immunoglobulin G1 for D11 and immunoglobulin G3 for B7. MAbs against BVDV strains 87-2552 and NADL were specific for their respective strains in virus neutralization assays. The results indicated significant antigenic differences between BVDV strain 87-2552 and the NADL and Singer strains.

Immune response to bovine viral diarrhea virus induced by anti-idiotypic antibodies

We have previously prepared rabbit anti-idiotypic antibodies (anti-Ids) against the neutralizing monoclonal antibodies (MAbs) specific for the gp53 of bovine viral diarrhea virus (BVDV). The anti-Ids, purified by sequential immunoaffinity chromatography, inhibited the immunizing MAb from binding to the original antigens and blocked BVDV infection of cell cultures. This study evaluated immune responses in mice to the purified anti-Id reagents. BVDV-specific neutralizing antibodies were induced by the anti-Ids. The antisera (Ab3) induced by the anti-Ids immunoprecipitated gp53 from BVDV-infected Madin-Darby bovine kidney (MDBK) cell lysates. However, lymphocyte-proliferative responses were specific only for the respective immunizing antigens. These results suggest that the anti-Ids may bear an internal image of the gp53 to stimulate production of antibody but not to stimulate a virus-specific cellular immune response in mice.

Monoclonal anti-idiotypes induce neutralizing antibodies to enterovirus 70 conformational epitopes

Monoclonal antibodies (MAbs) directed against the prototype enterovirus 70 (EV-70) strain J670/71 were generated and characterized in order to produce anti-idiotypic MAbs (MAb2s) for use as surrogate immunogens. Western immunoblot and radioimmunoprecipitation assays suggested that all the MAbs recognize conformational epitopes on the virion surface. An EV-70-neutralizing antibody, MAb/ev-12 (MAb1), was selected for the production of MAb2s. Five MAb2s were selected for their capacities to inhibit the interaction of MAb/ev-12 with EV-70 in dot immunobinding inhibition and immunofluorescence assays. In addition, these five MAb2s inhibited virus neutralization mediated by MAb/ev-12, suggesting that they recognize paratope-associated idiotopes. In competition enzyme immunosorbent assays, none of the five MAb2s recognized other neutralizing and nonneutralizing EV-70-specific MAbs, demonstrating that the MAb2s were specific for private idiotopes. Immunization with each of the MAb2s was carried out for the production of anti-anti-idiotypic antibodies (Ab3). All five MAb2s induced an immune response. Moreover, results suggested that they share idiotopes, since MAb2-MAb/ev-12 binding could be inhibited by homologous as well as heterologous Ab3s. Ab3 sera were shown to possess antibodies capable of immunoprecipitating 35S-labeled viral proteins in the same manner as MAb/ev-12. Nine of 15 mice immunized with MAb2s demonstrated Ab3 neutralizing activity specific for the prototype EV-70 strain, J670/71. The potential application of MAb2s to serve as surrogate immunogens for conformational epitopes is substantiated by the results presented in this report.

Bovine viral diarrhea virus-specific neutralizing antibodies induced by anti-idiotypic antibodies

Two murine neutralizing monoclonal antibodies (MAbs), 4D8 and 6D11, recognizing epitopes on gp53, a surface glycoprotein of bovine viral diarrhea virus (BVDV), were used to generate anti-idiotypic antibodies (anti-ids) in a calf. The polyclonal anti-ids were isolated from serum by affinity chromatography on their respective Ab-1-Sepharose columns, followed by repeated adsorption on isotype-matched antibody-Sepharose columns. The anti-ids reacted specifically with their respective Ab-1, but not with isotype-matched controls. They also inhibited the binding of their Ab-1 to BVDV in a concentration-dependent manner. Mice immunized with the two anti-id preparations developed antibodies to BVDV, which neutralized the virus in vitro.