Therapeutic equine hyperimmune antibodies with high and broad-spectrum neutralizing activity protect rodents against SARS-CoV-2 infection

Abstract

The emergence of SARS-CoV-2 variants stresses the continued need for broad-spectrum therapeutic antibodies. Several therapeutic monoclonal antibodies or cocktails have been introduced for clinical use. However, unremitting emerging SARS-CoV-2 variants showed reduced neutralizing efficacy by vaccine induced polyclonal antibodies or therapeutic monoclonal antibodies. In our study, polyclonal antibodies and F(ab’)2 fragments with strong affinity produced after equine immunization with RBD proteins produced strong affinity. Notably, specific equine IgG and F(ab’)2 have broad and high neutralizing activity against parental virus, all SARS-CoV-2 variants of concern (VOCs), including B.1.1,7, B.1.351, B.1.617.2, P.1, B.1.1.529 and BA.2, and all variants of interest (VOIs) including B.1.429, P.2, B.1.525, P.3, B.1.526, B.1.617.1, C.37 and B.1.621. Although some variants weaken the neutralizing ability of equine IgG and F(ab’)2 fragments, they still exhibited superior neutralization ability against mutants compared to some reported monoclonal antibodies. Furthermore, we tested the pre-exposure and post-exposure protective efficacy of the equine immunoglobulin IgG and F(ab’)2 fragments in lethal mouse and susceptible golden hamster models. Equine immunoglobulin IgG and F(ab’)2 fragments effectively neutralized SARS-CoV-2 in vitro, fully protected BALB/c mice from the lethal challenge, and reduced golden hamster’s lung pathological change. Therefore, equine pAbs are an adequate, broad coverage, affordable and scalable potential clinical immunotherapy for COVID-19, particularly for SARS-CoV-2 VOCs or VOIs.

Development, Histological, and Ultrastructural Evaluation of Sheep Hyperimmune Serum Therapy for COVID-19

“…In previous studies, horses have been utilized to generate hyperimmune serum against various viral infections (Zylberman et al, 2020;Moreira-Soto et al, 2021;Botosso et al, 2022). However, horses are expensive to acquire and challenging to handle.…”

“…While antiviral drugs, vaccines and monoclonal antibodies have been extensively studied, their production on a large scale remains challenging and expensive (Haghighi et al, 2022). An alternative approach utilizing hyperimmune serum derived from horses, rich in neutralizing antibodies, has shown promise as a potential therapeutic intervention Leon et al, 2021;Li et al, 2023). A hyperimmune serum formula can be 150 times more potent than convalescent plasma (da Costa et al, 2021).…”

Development and preclinical evaluation of equine-derived hyperimmune serum against SARS-CoV-2 infection in K-18 hACE2 transgenic (Tg) mice

“…Studies on treatments for COVID-19 have focused mainly on antiviral drugs such as remdesivir, ASC09, lopinavir/ritonavir, arbidol, interferon-alpha, and thymosin alpha-1. The use of these drugs in COVID-19 treatment is still being investigated and further research is ongoing to determine their effectiveness and safety (Zhang et al 2020, De Vito et al 2023, Li et al 2023.…”

“…Several hyperimmune serum formulations have been created from horses' plasma that was immunized with S1 protein, inactivated SARS-CoV-2 whole virus, or recombinant proteins (S1, N, and SEM) of the virus. These hyperimmune serum have demonstrated high neutralizing antibody levels in vitro in many global studies (Luis Eduardo Cunha et al 2020, Pan et al 2020, Botosso et al 2022, Li et al 2023. Equine hyperimmune serum is a well-known and easily scalable technology for producing high titers of neutralizing antibodies against specific pathogens such as rabies, tetanus, diphtheria and MERS-CoV (Moreira-Soto et al 2021, Li et al 2023.…”

“…These hyperimmune serum have demonstrated high neutralizing antibody levels in vitro in many global studies (Luis Eduardo Cunha et al 2020, Pan et al 2020, Botosso et al 2022, Li et al 2023. Equine hyperimmune serum is a well-known and easily scalable technology for producing high titers of neutralizing antibodies against specific pathogens such as rabies, tetanus, diphtheria and MERS-CoV (Moreira-Soto et al 2021, Li et al 2023. The specific antibodies against SARS-CoV-2 can neutralize the virus before it enters the host cells (Pan et al 2020, Botosso et al 2022.…”