Evaluating the impact of mAbs scaffold in binding and neutralization activity of Rotavirus-specific mAbs

Rotaviruses are the major causative agent for severe dehydrating diarrhea in infants and young children worldwide. Currently several oral rotavirus vaccines are available and have shown reduced effectiveness and more rapid waning of antibodies in low- and middle-income countries (LMICs) compared to high-income countries (HICs). Neutralizing and non-neutralizing antibodies against the major viral proteins are detected after infection, and higher titers are associated with protection from disease. Antibodies (Abs) are heterodimeric proteins produced by B-cells. They belong to the immunoglobulin super-family and are composed of two heavy (H) and two light (L) chains (κ or λ). Heavy chains are linked by a disulfide bridge and can be IgA, IgD, IgE, IgG and IgM isotypes, each with different functions in the adaptive immune system. IgA can be found either in their monomeric, dimeric, or tetrameric form (when two dimeric IgAs are linked by the secretory component), which exert their function in the mucosae. Historically, isolated Rotavirus-specific monoclonal Abs (mAbs) are produced in IgG1 scaffold, regardless of whether their native scaffold was IgG or IgA. To understand the impact of antibodies scaffolds in the immune response against rotavirus, we produced mAbs targeting VP8* and VP7 viral proteins, starting from published sequences, expressing them in IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2 scaffolds and as dimeric IgA. mAbs were fully characterized for their binding to the viral target and their functionality was assessed in neutralization assays with 3 different Rotavirus strains (G1P[8], G2P[4], G9P[8]). We found that monoclonal antibodies (mAbs) targeting the same epitope when expressed in different scaffold induced differential neutralization activity. These generated mAbs serve as tools to dissect in vitro the response to rotavirus and to extend our understanding of the polyclonal antibody response generated during either natural infection or following vaccination.