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

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.

A Comparative Study of Chest CT With Lung Ultrasound After SARS-CoV-2 Infection in the Assessment of Pulmonary Lesions in Rhesus Monkeys (Macaca Mulatta)

“…In addition, it could also include other animal species like dogs and cats in which LUS has proven to be a useful technique but also warrants further investigation to use as a stand-alone imaging modality (39,40). Moreover, to assess the full potential of LUS in NHPs, the effect of different levels of disease severity with respect to the diagnostic efficacy of LUS over CT needs to be evaluated probably in other lung disease models like tuberculosis or influenza (41,42).…”

Symptom propagation in respiratory pathogens of public health concern: a review of the evidence

“…Our identified relevant studies (3/3) [84,103,104] indicate that more severe symptoms were associated with increased aerosol production. Similarly, all studies (7/7) [95,[105][106][107][108][109][110] gave evidence that infection via aerosols resulted in more severe symptoms than infection via direct contact (including fomite transmission) or large droplet transmission.…”

“…Animal model studies have shown that, relative to intranasal inoculation, aerosol inoculation results in more frequent LRT symptoms [105] and worse severity [106]. Mooij et al [107] found more severe symptoms in macaques when inoculation was directly into the lungs (4/12 were fatal) compared to other studies that used intratracheal inoculation (generally only mild symptoms despite similarly pathogenic strains and comparable doses). Similarly, Yetter et al [108] found more severe symptoms in mice when inoculation occurred in the LRT (15/16 were fatal) compared to the URT (1/16 was fatal).…”

Animal Models for Influenza Research: Strengths and Weaknesses

“…While rhesus macaques have been selected for pathogenic studies and the evaluation of therapeutic and prophylactic strategies [147], the pig-tailed macaque is recommended for transcriptional studies of influenza virus [148]. Cynomolgus macaques have recently been used for various influenza studies [149][150][151].…”