Pre-exposure antibody prophylaxis protects macaques from severe influenza

Area of Science:

• Virology
• Immunology
• Infectious Diseases

Background:

• Influenza viruses, including avian H5N1, pose significant global health risks due to recurrent zoonotic spillovers and pandemic potential.
• Seasonal epidemics and pandemics caused by influenza viruses result in substantial mortality and morbidity worldwide.
• Development of effective countermeasures against highly pathogenic influenza strains is crucial for public health preparedness.

Purpose of the Study:

• To evaluate the efficacy of pre-exposure prophylaxis with a broadly neutralizing antibody (bnAb), MEDI8852, in protecting non-human primates against highly pathogenic avian influenza H5N1 virus.
• To determine the dose-dependency and the role of Fc-mediated effector functions in the protective mechanism of MEDI8852 against H5N1 infection.

Main Methods:

• Cynomolgus macaques were administered varying doses of MEDI8852 as pre-exposure prophylaxis.
• Animals were subsequently challenged via aerosolization with a highly pathogenic avian influenza H5N1 virus.
• Clinical outcomes, including respiratory function and survival, were monitored and compared between treatment groups and controls.

Main Results:

• Pre-exposure prophylaxis with MEDI8852 demonstrated high efficacy in protecting macaques from severe disease and fatality following H5N1 challenge.
• Protection was observed to be dose-dependent, with significant protection achieved at doses of 10 mg/kg or higher.
• Negligible impairment of respiratory function was noted in macaques receiving adequate doses of MEDI8852, unlike unprotected control animals.

Conclusions:

• Broadly neutralizing antibody (bnAb) MEDI8852 is a highly effective prophylactic agent against severe H5N1 avian influenza in a primate model.
• The protective effect of MEDI8852 is antibody dose-dependent and, at the tested doses, does not rely on Fc-mediated effector functions.
• MEDI8852 and similar bnAbs hold promise for protecting against future, currently unforeseen, pandemic influenza A viruses.