ABSTRACT
Influenza virus is a global health concern due to its unpredictable pandemic potential. Frequent mutations of surface molecules, hemagglutinin (HA) and neuraminidase (NA), contribute to low efficacy of the annual flu vaccine and therapeutic resistance to standard antiviral agents. The populations at high risk of influenza virus infection, such as the elderly and infants, generally mount low immune responses to vaccines, and develop severe disease after infection. Novel therapeutics with high effectiveness and mutation resistance are needed. Previously, we described the generation of a fully human influenza virus matrix protein 2 (M2) specific monoclonal antibody (mAb), Z3G1, which recognized the majority of M2 variants from natural viral isolates, including highly pathogenic avian strains. Passive immunotherapy with Z3G1 significantly protected mice from the infection when administered either prophylactically or 1-2days post infection. In the present study, we showed that Z3G1 significantly protected mice from lethal infection when treatment was initiated 3days post infection. In addition, therapeutic administration of Z3G1 reduced lung viral titers in mice infected with different viral strains, including amantadine and oseltamivir-resistant strains. Furthermore, prophylactic and therapeutic administration of Z3G1 sustained O2 saturation and reduced lung pathology in monkeys infected with a pandemic H1N1 strain. Finally, de-fucosylated Z3G1 with an IgG1/IgG3 chimeric Fc region was generated (AccretaMab® Z3G1), and showed increased ADCC and CDC in vitro. Our data suggest that the anti-M2 mAb Z3G1 has great potential as a novel anti-flu therapeutic agent.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Antibodies, Viral/administration & dosage , Immunization, Passive , Influenza A virus/drug effects , Influenza, Human/drug therapy , Animals , Antibodies, Monoclonal/immunology , Antibodies, Viral/immunology , Drug Evaluation, Preclinical , Female , Humans , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H1N1 Subtype/physiology , Influenza A virus/physiology , Influenza, Human/immunology , Influenza, Human/virology , Macaca , Male , Mice , Mice, Inbred C57BL , Viral Matrix Proteins/immunologyABSTRACT
The mouse embryonic stem cell test (mEST) is used to assess the embryotoxicity of drug candidates by evaluating the effects on the cardiac differentiation of stem cells. However, thalidomide embryotoxicity has not yet been reported using the mEST. To detect the effects of thalidomide, we used human induced pluripotent stem cells (hiPSCs) instead of mouse embryonic stem cells, and assessed three endpoints: the inhibition of cardiac differentiation, the cytotoxicity to hiPSCs, and the cytotoxicity to human dermal fibroblasts, according to the mEST. From these data (IC50 values), the embryotoxicity was classified into one of three different classes based on the mEST and our criteria. Valproate was used as a positive control and ascorbic acid was used as a negative control, and their effects were assessed. Similar to valproate, thalidomide was classified as a Class 2 agent, with weak embryotoxicity, by the mEST criteria, and was classified as Category 3 embryotoxic based on our criteria. Ascorbic acid was classified as a Class 1 / Category 1, non-embryotoxic agent, based on both criteria. Thalidomide embryotoxicity was detected in the embryonic stem cell test based on hiPSCs. This test system is thus considered to have a much greater predictive ability than the mEST.
