A potent neutralizing IgM mAb targeting the N218 epitope on E2 protein protects against Chikungunya virus pathogenesis

Abstract

Keywords: envelope 2 protein, epitope, monoclonal antibody, virus pathogenesis Chikungunya virus (CHIKV) is a medically important human viral pathogen that causes Chikungunya fever accompanied with debilitating and persistent joint pain. Host-elicited or passively-transferred monoclonal antibodies (mAb) are essential mediators of CHIKV clearance. Therefore, this study aimed to generate and characterize a panel of mAbs for their neutralization efficacy against CHIKV infection in a cell-based and murine model.To evaluate their antigenicity and neutralization profile, indirect enzyme-linked immunosorbent assay (ELISA), an immunofluorescence assay (IFA) and a plaque reduction neutralization test were performed on mAbs of IgM isotype. CHIKV escape mutants against mAb 3E7b neutralization were generated, and reverse genetics techniques were then used to create an infectious CHIKV clone with a single mutation. 3E7b was also administered to neonate mice prior or after CHIKV infection. The survival rate, CHIKV burden in tissues and histopathology of the limb muscles were evaluated. Both IgM 3E7b and 8A2c bind strongly to native CHIKV surface and potently neutralize CHIKV replication. Further analyses of 3E7b binding and neutralization of CHIKV single-mutant clones revealed that N218 of CHIKV E2 protein is a potent neutralizing epitope. In a pre-binding neutralization assay, 3E7b blocks CHIKV attachment to permissive cells, possibly by binding to the surface-accessible E2-N218 residue. Prophylactic administration of 3E7b to neonate mice markedly reduced viremia and protected against CHIKV pathogenesis in various mice tissues. Given therapeutically at 4 h post-infection, 3E7b conferred 100% survival rate and similarly reduced CHIKV load in most mice tissues except the limb muscles. Collectively, these findings highlight the usefulness of 3E7b for future prophylactic or epitope-based vaccine design.

Chikungunya virus: epidemiology, replication, disease mechanisms, and prospective intervention strategies

“…An IgG response can be detected approximately 7-10 days after onset of illness, often after viremia has been cleared (37,(154)(155)(156). Many mouse and human IgM and IgG antibodies broadly and potently neutralize CHIKV (157)(158)(159)(160)(161)(162). The most potently neutralizing antibodies target domains A and B of the E2 glycoprotein, with those targeting domain B often displaying broad neutralization against multiple strains of CHIKV and other related alphaviruses (157,(159)(160)(161).…”

“…Many mouse and human IgM and IgG antibodies broadly and potently neutralize CHIKV (157)(158)(159)(160)(161)(162). The most potently neutralizing antibodies target domains A and B of the E2 glycoprotein, with those targeting domain B often displaying broad neutralization against multiple strains of CHIKV and other related alphaviruses (157,(159)(160)(161). In B cell-deficient (μMT) mice, persistent, steady-state viremia occurs following CHIKV infection (147,150), further highlighting the importance of neutralizing antibodies in mitigating CHIKV disease.…”

Prediction of MAYV peptide antigens for immunodiagnostic tests by immunoinformatics and molecular dynamics simulations

“…The p_MAYV4 peptide is more likely to be recognized by neutralizing antibodies produced during MAYV infection because domain A of the E2 glycoprotein has greater solvent exposure than domain C 17,35 . It is known that the neutralizing antibodies against Alphavirus are directed mainly to targets present in domains A and B of the E2 glycoprotein 21,26,28,35,36 . Therefore, due to the location of the p_MAYV4a peptide in domain A of the E2 glycoprotein, close to the cellular receptor binding site (THR58) 38,39 , we hypothesize that antibody binding in this region is associated with inhibited cell recognition.…”

“…Cryogenic electron microscopy (cryo-EM) images of CHIKV 21,22 , Venezuelan Equine Encephalitis virus (VEEV) 23 , Barmah Forest virus (BFV) 24 and Sindbis virus (SINV) 25 show that E1/E2 glycoproteins form dimeric spicules on the membrane surface with regions exposed to the extracellular medium 24 . Exposure of E1/E2 glycoprotein residues to the extracellular environment enables their interaction with neutralizing antibodies, making them interesting targets for therapeutic and diagnostic studies 19,26–29 .…”

Arbovirus en Latinoamérica

“…Esta profilaxis podría incluso recomendarse a neonatos nacidos de madres virémicas, y que están en riesgo de desarrollo de infección severa. 44,47,53 Similar al dengue, la fiebre chikungunya se encuentra en el mismo escenario con sólo dos vacunas candidatas, las cuales recientemente se aprobaron para entrar a ensayos clínicos de fase II. Una versión con partículas virales similares llamada VRC 311 y una vacuna recombinante con virus de sarampión vivos atenuados.…”