The Potential of O’nyong-nyong Virus Strain SG650 Murine Monoclonal Antibodies for Detection of O’nyong-nyong and Chikungunya Viruses

O’nyong-nyong virus (ONNV) and Chikungunya virus (CHIKV) are antigenically related alphaviruses responsible for febrile illnesses common to the tropics and associated with relatively high morbidity and mortality. Murine monoclonal antibodies (mAbs) targeting alphaviruses like Chikungunya have been developed and used to make commercially available kits. However, few studies have been conducted to develop antibodies specific to ONNV and no commercial kits are available for use in endemic regions where outbreak potential is high. We demonstrate the potential of in-house generated monoclonal antibodies against ONNV to detect both ONNV and CHIKV. The objective of this study was to generate mAbs using hybridoma technology, characterize the developed mAbs, determine their specificity against selected alphaviruses and check their diagnostic potential using an indirect IgG enzyme-linked immunosorbent assay (ELISA) and focus neutralization assay (FRNT50). BALB/c mice were immunized with ONNV purified proteins from ONNV infectious culture fluid. After four rounds of booster injections, the mice were sacrificed, spleen cells harvested and fused with parental myeloma cells then cultured in selective media and the successful hybrid clones with antibody-producing ability purified to yield the desired mAbs. Five monoclonal antibodies targeting the ONNV E1 protein of isotypes IgG2a/kappa, IgG2b/kappa and IgM/kappa (P1B12, P1E9, P1G11, P1B4 and P1G6) demonstrated a potential to detect both ONNV and CHIKV isolates by indirect IgG ELISA but no potential for neutralization of the viruses by FRNT50. This study demonstrates the potential efficacy of in-house serological tools as an alternative in the absence of commercial assays in screening and diagnosis of ONN and CHIK viruses which are often co-circulating. It is our recommendation that this work may be pursued further to design and optimize ELISA assays, using the developed mAbs, for the detection of both ONN and CHIK viruses in the research laboratory set-up

Murine Monoclonal Antibodies against the Receptor Binding Domain of SARS-CoV-2 Neutralize Authentic Wild-Type SARS-CoV-2 as Well as B.1.1.7 and B.1.351 Viruses and Protect In Vivo in a Mouse Model in a Neutralization-Dependent Manner

Cross-neutralization of SARS-CoV-2 variants by RBD-targeting antibodies is still not well understood, and very little is known about the potential protective effect of nonneutralizing antibodies in vivo . Using a panel of mouse monoclonal antibodies, we investigate both of these points.

Mouse Antibodies with Activity Against the SARS-CoV-2 D614G and B.1.351 Variants

With the rapid spread of SARS-CoV-2 variants, including those that are resistant to antibodies authorized for emergency use, it is apparent that new antibodies may be needed to effectively protect patients against more severe disease. Differences between the murine and human antibody repertoires may allow for the isolation of murine monoclonal antibodies that recognize a different or broader range of SARS-CoV-2 variants than the human antibodies that have been characterized so far. We describe mouse antibodies B13 and O24 that demonstrate neutralizing potency against SARS-CoV-2 Wuhan (D614G) and B.1.351 variants. Such murine antibodies may have advantages in protecting against severe symptoms when individuals are exposed to new SARS-CoV-2 variants.

Murine monoclonal antibodies against RBD of SARS-CoV-2 neutralize authentic wild type SARS-CoV-2 as well as B.1.1.7 and B.1.351 viruses and protect in vivo in a mouse model in a neutralization dependent manner

After first emerging in December 2019 in China, severe acute respiratory syndrome 2 (SARS-CoV-2) has since caused a pandemic leading to millions of infections and deaths worldwide. Vaccines have been developed and authorized but supply of these vaccines is currently limited. With new variants of the virus now emerging and spreading globally, it is essential to develop therapeutics that are broadly protective and bind conserved epitopes in the receptor binding domain (RBD) or the whole spike of SARS-CoV-2. In this study, we have generated mouse monoclonal antibodies (mAbs) against different epitopes on the RBD and assessed binding and neutralization against authentic SARS-CoV-2. We have demonstrated that antibodies with neutralizing activity, but not non-neutralizing antibodies, lower viral titers in the lungs when administered in a prophylactic setting in vivo in a mouse challenge model. In addition, most of the mAbs cross-neutralize the B.1.351 as well as the B.1.1.7 variants in vitro.

Screening and development of monoclonal antibodies for identification of ferret T follicular helper cells

The ferret is a key animal model for investigating the pathogenicity and transmissibility of important human viruses, and for the pre‐clinical assessment of vaccines. However, relatively little is known about the ferret immune system, due in part to a paucity of ferret‐reactive reagents. In particular, T follicular helper (Tfh) cells are critical in the generation of effective humoral responses in humans, mice and other animal models but to date it has not been possible to identify Tfh in ferrets. Here, we describe the screening and development of ferret-reactive BCL6, CXCR5 and PD-1 monoclonal antibodies. We found two commercial anti-BCL6 antibodies (clone K112-91 and clone IG191E/A8) had cross-reactivity with lymph node cells from influenza-infected ferrets. We next developed two murine monoclonal antibodies against ferret CXCR5 (clone feX5-C05) and PD-1 (clone fePD-CL1) using a single B cell PCR-based method. We were able to clearly identify Tfh cells in lymph nodes from influenza infected ferrets using these antibodies. The development of ferret Tfh marker antibodies and the identification of ferret Tfh cells will assist the evaluation of vaccine-induced Tfh responses in the ferret model and the design of novel vaccines against the infection of influenza and other viruses, including SARS-CoV2.

Identification of a neutralizing epitope within minor repeat region of Plasmodium falciparum CS protein

Malaria remains a major cause of morbidity and mortality worldwide with 219 million infections and 435,000 deaths predominantly in Africa. The infective Plasmodium sporozoite is the target of a potent humoral immune response that can protect murine, simian and human hosts against challenge by malaria-infected mosquitoes. Early murine studies demonstrated that sporozoites or subunit vaccines based on the sporozoite major surface antigen, the circumsporozoite (CS) protein, elicit antibodies that primarily target the central repeat region of the CS protein. In the current murine studies, using monoclonal antibodies and polyclonal sera obtained following immunization with P. falciparum sporozoites or synthetic repeat peptides, we demonstrate differences in the ability of these antibodies to recognize the major and minor repeats contained in the central repeat region. The biological relevance of these differences in fine specificity was explored using a transgenic P. berghei rodent parasite expressing the P. falciparum CS repeat region. In these in vitro and in vivo studies, we demonstrate that the minor repeat region, comprised of three copies of alternating NANP and NVDP tetramer repeats, contains an epitope recognized by sporozoite-neutralizing antibodies. In contrast, murine monoclonal antibodies specific for the major CS repeats (NANP)n could be isolated from peptide-immunized mice that had limited or no sporozoite-neutralizing activity. These studies highlight the importance of assessing the fine specificity and functions of antirepeat antibodies elicited by P. falciparum CS-based vaccines and suggest that the design of immunogens to increase antibody responses to minor CS repeats may enhance vaccine efficacy.