Identification and Characterization of a Novel Single Domain Antibody Against Ebola Virus

A review on camelid nanobodies with potential application in veterinary medicine

The single variable domains of camelid heavy-chain only antibodies, known as nanobodies, have taken a long journey since their discovery in 1989 until the first nanobody-based drug's entrance to the market in 2022. On account of their unique properties, nanobodies have been successfully used for diagnosis and therapy against various diseases or conditions. Although research on the application of recombinant antibodies has focused on human medicine, the development of nanobodies has paved the way for incorporating recombinant antibody production in favour of veterinary medicine. Currently, despite many efforts in developing these biomolecules with diversified applications, significant opportunities exist for exploiting these highly versatile and cost-effective antibodies in veterinary medicine. The present study attempts to identify existing gaps and shed light on paths for future research by presenting an updated review on camelid nanobodies with potential applications in veterinary medicine.

Broadly Reactive Nanobody Targeting the H3 Hemagglutinin of the Influenza A Virus

Monoclonal antibodies and recombinant antibody fragments are a very promising therapeutic tool to combat infectious diseases. Due to their unique paratope structure, nanobodies (VHHs) hold several advantages over conventional monoclonal antibodies, especially in relation to viral infections. Influenza A viruses (IAVs) remain a major threat to public health. The hemagglutinin (HA) protein is the main protective and immunodominant antigen of IAVs. In this study, three broadly reactive nanobodies (D9.2, E12.2, and D4.2) to H3N2 influenza strains were isolated and Fc-fusion proteins (VHH-Fcs) were obtained and characterized in vitro. This modification improved the nanobodies' binding activity and allowed for their interaction with a wider range of strains. The D9.2-Fc antibody showed a 100% protection rate against mortality in vivo in a mouse lethal model. Furthermore, we demonstrated that the observed protection has to do with Fc-FcγR interactions. These results indicate that D9.2-Fc can serve as an effective antiviral agent against the H3N2 influenza infection.

Ebola virus VP35 perturbs type I interferon signaling to facilitate viral replication

As one of the deadliest viruses, Ebola virus (EBOV) causes lethal hemorrhagic fevers in humans and nonhuman primates. The suppression of innate immunity leads to robust systemic virus replication of EBOV, leading to enhanced transmission. However, the mechanism of EBOV-host interaction is not fully understood. Here, we identified multiple dysregulated genes in early stage of EBOV infection through transcriptomic analysis, which are highly clustered to Jak-STAT signaling. EBOV VP35 and VP30 were found to inhibit type I interferon (IFN) signaling. Moreover, exogenous expression of VP35 blocks the phosphorylation of endogenous STAT1, and suppresses nuclear translocation of STAT1. Using serial truncated mutations of VP35, N-terminal 1-220 amino acid residues of VP35 were identified to be essential for blocking on type I IFN signaling. Remarkably, VP35 of EBOV suppresses type I IFN signaling more efficiently than those of Bundibugyo virus (BDBV) and Marburg virus (MARV), resulting in stable replication to facilitate the pathogenesis. Altogether, this study enriches understanding on EBOV evasion of innate immune response, and provides insights into the interplay between filoviruses and host.

Emerging Pathogenic Viral Infections of the Eye

Global health security threats and the public health impact resulting from emerging infectious diseases including the ongoing COVID-19 pandemic and recent Ebola virus disease outbreaks continuously emphasize the need for a comprehensive approach to preparedness, management of disease outbreaks, and health sequelae associated with emergent pathogens. A spectrum of associated ophthalmic manifestations, along with the potential persistence of emerging viral pathogens in ocular tissues, highlight the importance of an ophthalmic approach to contributing to efforts in the response to public health emergencies from disease outbreaks. This article summarizes the ophthalmic and systemic findings, epidemiology, and therapeutics for emerging viral pathogens identified by the World Health Organization as high-priority pathogens with epidemic potential.

Ebanga™: The most recent FDA-approved drug for treating Ebola

Ebolavirus (EBOV) is a virulent pathogen that causes Ebola virus disease (EVD), which is a life-threatening human condition with a fatality rate of up to 90%. Since the first outbreak in Africa in 1976, several outbreaks and epidemics of EBOV have occurred across the globe. While EVD is recognized as a serious threat to human health and outbreaks occur almost every year, the treatment options for the disease are limited. In designing therapeutic strategies against EBOV infection, viral structural proteins, such as glycoprotein (GP), could be an excellent target for neutralizing the virus. According to the latest research, GP-specific antibodies are the most efficient post-exposure treatments for EVD. Ansuvimab-zykl, i.e., mAb114 (Ebanga™), is a recent FDA-approved human immunoglobulin monoclonal antibody targeting EBOV GP. This review provides a brief overview of the pharmacological effects and safety profile of ansuvimab in clinical trials and provides insights into the precise mechanism of this new drug for treating EVD.

Therapeutic applications of nanobodies against SARS-CoV-2 and other viral infections: Current update

In the last two years, the world encountered the SARS-CoV-2 virus, which is still dominating the population due to the absence of a viable treatment. To eradicate the global pandemic, scientists, doctors, and researchers took an exceptionally significant initiative towards the development of effective therapeutics to save many lifes. This review discusses about the single-domain antibodies (sdAbs), also called nanobodies, their structure, and their types against the infections of dreadful SARS-CoV-2 virus. A precise description highlights the nanobodies and their therapeutic application against the other selected viruses. It aims to focus on the extraordinary features of these antibodies compared to the conventional therapeutics like mAbs, convalescent plasma therapy, and vaccines. The stable structure of these nanobodies along with the suitable mechanism of action also confers greater resistance to the evolving variants with numerous mutations. The nanobodies developed against SARS-CoV-2 and its mutant variants have shown the greater neutralization potential than the primitive ones. Engineering of these specialized antibodies by modern biotechnological approaches will surely be more beneficial in treating this COVID-19 pandemic along with certain other viral infections.

Immunotherapy targeting mesothelin in acute myeloid leukemia

Mesothelin (MSLN) is an emerging target that exists in soluble and membrane-associated forms. It is usually used for the diagnosis and treatment of MSLN-positive solid tumors. Interestingly, recent studies have shown that MSLN is highly expressed in 36% of acute myeloid leukemia (AML) patients and barely expressed in normal hematopoietic cells, which makes MSLN a promising target for the treatment of AML. It has been shown that MSLN is detectable as a diagnostic marker in its soluble form. Although the mechanism of action is unclear, MSLN remains a promising target for immunotherapy. Most MSLN research has been conducted in solid tumors, and less research has been conducted in hematopoietic tumors. Increasing research on MSLN is underway in AML, a hematopoietic neoplasm. For example, MSLN is related to extramedullary disease, minimal residual disease, and relapse in AML patients. Decreasing the expression of MSLN reduces the severity of the disease course. This information suggests that MSLN may be an ideal target for the treatment of many AML-related diseases to improve the prognosis and survival rate. At present, there are a few immunotherapies targeting MSLN in AML in preclinical and clinical trials, such as antibody-drug conjugates, bispecific T-cell engagers, and chimeric antigen receptor-T cells, which opens new room for the treatment of MSLN-related AML.