Potent Neutralization Ability of a Human Monoclonal Antibody Against Serotype 1 Dengue Virus

A human monoclonal antibody to neutralize all four serotypes of dengue virus derived from patients at the convalescent phase of infection

Dengue virus (DENV) is a prevalent mosquito-transmitted human pathogen, causing about 100 million cases of acute dengue fever and 21,000 deaths annually worldwide. Therapeutic neutralizing antibodies against dengue virus might be effective to treat severe dengue fever. Here, we showed that human monoclonal antibody (HMAb) 9C7 bound to all four intact serotypes of DENV but not to the recombinant envelope protein, suggesting HMAb 9C7 recognized a conformational epitope of the envelope protein. Taken together our results suggested that HMAb 9C7 neutralized all four serotypes of DENV in vitro and, for DENV-1, indicated activity at the pre- and post-attachment steps in the viral life cycle. HMAb 9C7 potently protected suckling mice from lethal challenge with all four serotypes of DENV. FcγRII-mediated uptake of immune complexes and antibody-dependent enhancement at low doses of the antibody were abolished by two Leu-to-Ala (9C7-LALA) mutations or deletion of nine amino acids (9C7-9del) in HMAb 9C7 Fc. Therefore, HMAb 9C7 represented a promising prophylactic and therapeutic agent against all four serotypes of DENV.

Flavivirus Entry Inhibitors

Flaviviruses, including Dengue virus, Zika virus, Yellow fever virus, Japanese encephalitis virus, West Nile virus, cause thousands of deaths and millions of illnesses each year. The large outbreak of ZIKV in 2016 reminds us that flaviviruses can pose a serious threat to human safety and public health as emerging and re-emerging viruses. However, there are no specific drugs approved for the treatment of flavivirus infections. Due to no need to enter the cells, viral entry inhibitors have the unique advantage in suppressing viral infections. Flaviviruses bind to receptors and attach to the cell surface, then enter the endosome in a clathrin-dependent manner and finalizes the viral entry process after fusion with the cell membrane in a low pH environment. Small molecules, antibodies or peptides can inhibit flavivirus entry by targeting the above processes. Here, we focus on flavivirus entry inhibitors with well-defined target and antiviral activity. We hope that our review will provide a theoretical basis for flavivirus treatment and drug research and help to accelerate the clinical application of flavivirus entry inhibitors.

A human bispecific neutralization antibody against four serotypes of dengue virus

In tropical and subtropical countries, dengue virus (DENV) infections have been increasing; however, we still lack effective therapy. In the present study, we aimed to engineer a bispecific antibody (subsequently named LUZ-8F2-6B1), based on monoclonal antibody 6B1, which has anti DENV-1, 2, and 3 activity, and 8F2, which has anti DENV-4 activity. LUZ-8F2-6B1 displayed potent neutralization activity against four serotypes of DENV by binding to the envelop protein. In vivo, we demonstrated that LUZ-8F2-6B1 could provide protection against infection by four serotypes of DENV in a mouse model. In addition, the deletion of nine amino acids in the Fc region (LUZ-8F2-6B1-9del) completely abolished the antibody-dependent enhancement observed at lower doses of the antibody. Thus, LUZ-8F2-6B1 is a promising, safe, and effective agent for the prophylaxis and treatment of DENV infection.

A novel human monoclonal antibody potently neutralizes human adenovirus serotype 7 by primarily targeting the adenovirus hexon protein

Human adenovirus serotype 7 (HAdV-7), belonging to species B, has caused severe lower respiratory tract diseases and even deaths recently. However, no adenovirus vaccine or therapeutic is available thus far. In this study, a HAdV-7-specific human monoclonal antibody (HMAb), 3-3E, isolated from single plasma cells obtained from the peripheral blood mononuclear cells of HAdV-7-infected patients showed potent HAdV-7 neutralization activity. The results showed HMAb 3-3E only binds to the hexon protein of intact HAdV-7 or the recombinant hexon protein and it does not bind to other intact virion particles. This could mean the antibody recognizes a conformational epitope of the hexon protein. Further, HMAb 3-3E potently neutralized HAdV-7 in vitro at low concentrations. In vivo studies showed HMAb 3-3E protected from HAdV-7 infection in a murine model. Therefore, HMAb 3-3E is promising as a safe and effective prophylactic and therapeutic treatment for HAdV-7 infection.

A Murine Monoclonal Antibody With Potent Neutralization Ability Against Human Adenovirus 7

B1-type human adenoviruses (HAdVs) HAdV-3, HAdV-7, and HAdV-55 have caused epidemics in North America, Asia, and Europe. However, to date, no adenovirus vaccines or antiviral drugs have been approved for general use. In the present work, a scFv-phage immune library was constructed and mouse monoclonal antibody (MMAb) 10G12 was obtained through selection. 10G12 is specific for HAdV-7 and binds the hexon loop1 and loop2 (LP12), resulting in strong neutralization activity against HAdV-7. Additionally, it is stable in serum and buffer at various pH values. The findings provide insight into adenovirus and antibody responses and may facilitate the design and development of adenovirus vaccines and antiviral drugs.