Aerosolized Exposure to H5N1 Influenza Virus Causes Less Severe Disease Than Infection via Combined Intrabronchial, Oral, and Nasal Inoculation in Cynomolgus Macaques.

Petra Mooij,Willy M J M Bogers,Ivanela Kondova,Nikki Van Driel,Marieke A Stammes,Zahra Fagrouch,Ernst J Verschoor,Daniella Mortier,Gerrit Koopman

doi:10.3390/v13020345

Abstract

Infection with highly pathogenic avian H5N1 influenza virus in humans often leads to severe respiratory disease with high mortality. Experimental infection in non-human primates can provide additional insight into disease pathogenesis. However, such a model should recapitulate the disease symptoms observed in humans, such as pneumonia and inflammatory cytokine response. While previous studies in macaques have demonstrated the occurrence of typical lesions in the lungs early after infection and a high level of immune activation, progression to severe disease and lethality were rarely observed. Here, we evaluated a routinely used combined route of infection via intra-bronchial, oral, and intra-nasal virus inoculation with aerosolized H5N1 exposure, with or without the regular collection of bronchoalveolar lavages early after infection. Both combined route and aerosol exposure resulted in similar levels of virus replication in nose and throat and similar levels of immune activation, cytokine, and chemokine release in the blood. However, while animals exposed to H5N1 by combined-route inoculation developed severe disease with high lethality, aerosolized exposure resulted in less lesions, as measured by consecutive computed tomography and less fever and lethal disease. In conclusion, not virus levels or immune activation, but route of infection determines fatal outcome for highly pathogenic avian H5N1 influenza infection.

Highlights

Avian influenza viruses naturally circulate in wild aquatic birds but are transmitted to poultry
In a study described by Rimmelzwaan et al, the one animal that became severely ill had been subjected to bronchoalveolar lavages (BAL) collection [14]. In view of these contradictory results regarding the role of aerosolized exposure in causing severe disease in Non-human primates (NHP), we evaluated disease severity following H5N1 infection by aerosolized exposure, either with or without BAL collection at day 2, 4, and 7 after virus inoculation and compared the outcome with a combined route of virus inoculation
In order to evaluate whether aerosolized exposure and collection of BAL could have an impact on the course of H5N1 infection, three groups of four cynomolgus macaques were exposed to 6 × 106 TCID50 of the highly pathogenic avian influenza virus strain

Summary

Introduction

Avian influenza viruses naturally circulate in wild aquatic birds but are transmitted to poultry They can infect humans who come into close contact with infected birds, for instance at wild poultry markets or commercial farms [1]. Infection generally starts as a typical upper respiratory tract infection accompanied by clinical symptoms such as fever and body aches. It develops into lower respiratory tract infection and causes a severe pneumonia progressing to acute respiratory distress syndrome and death [3]. It is not clear whether virus replication and local tissue damage or rather the level of immune activation and cytokine production are the main determinants in causing fatal disease

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