Antibodies are capable of having an impact on organisms in the absence of effector cells or effector molecules such as complements. In vivo, it is conventional to distinguish phenomenologically between two types of antibody antiviral activity. One is the ability of antibodies to protect against infection when it is present before or immediately following infection. The other is the ability of antibodies to interfere with an established infection.
Fig.1 Natural antibodies and pathogen-specific immune antibodies. (Maddur, 2020)
Natural antibodies (nAbs) have been defined as preimmune antibodies generated in the absence of exogenous antigenic stimulation, which are broadly reactive, low affinity, germline-like antibodies selected in the presence of endogenous antigen. NAbs are formed from the subpopulation of B lymphocytes, mainly B1 lymphocytes and B lymphocytes of the marginal zone. NAbs, belonging to isotypes IgM, IgG3 and IgA, are the first line of defense against infections before the creation of germinal centers in which adaptive antibodies are formed. NAbs specific for infectious pathogens are found at low titer in the serum of healthy, non-immunized, individuals. Their important physiological role for enhancing the survival of the host seems to be in early resistance against infections. NAbs provide a link between the innate and adaptive immune system. NAbs restrict viral dissemination by direct neutralization, complement activation, and targeting the virus to the splenic marginal zone that contributes to the induction of early T-independent antibody responses.
Fig.2 Natural antibodies link innate and adaptive immunity. (Matter, 2008)
In contrast to Nabs, the immune system cells produce adaptive antibodies in a specific response to viral infection. In general, virus-specific antibodies are considered antiviral and play an important role in the control of virus infections in a number of ways. Antibodies can exert their protective functions via a multitude of mechanisms, such as neutralization, activation of complement, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). In general, the ability of antibodies to protect in vivo correlates with their neutralizing activity. However, this correlation is not absolute. Unlike antiviral activity of antibodies in vitro, non-neutralizing antibodies can similarly bind to viral proteins expressed on infected cells to produce antiviral activity.
ViroAntibody refers to the antibody, especially for virology researches. Creative Biolabs has devoted to the field of ViroAntibody services and provide a myriad of ViroAntibodies. In addition, we have a myriad of viruses and models available to provide optional approaches for testing antiviral activity. Please feel free to contact us for further information.