The viral distribution and pathological characteristics of BALB/c mice infected with highly pathogenic Influenza H7N9 virus

Abstract

Background The highly pathogenic Influenza H7N9 virus is believed to cause multiple organ infections. However, there have been few systematic animal experiments demonstrating the virus distribution after H7N9 virus infection. The present study was carried out to investigate the viral distribution and pathological changes in the main organs of mice after experimental infection with highly pathogenic H7N9 virus. Methods Infection of mice with A/Guangdong/GZ8H002/2017(H7N9) virus was achieved via nasal inoculation. Mice were killed at 2, 3, and 7 days post infection. The other mice were used to observe their illness status and weight changes. Reverse transcription polymerase chain reaction and viral isolation were used to analyse the characteristics of viral invasion. The pathological changes of the main organs were observed using haematoxylin and eosin staining and immunohistochemistry. Results The weight of H7N9 virus-infected mice increased slightly in the first two days. However, the weight of the mice decreased sharply in the following days, by up to 20%. All the mice had died by the 8th day post infection and showed multiple organ injury. The emergence of viremia in mice was synchronous with lung infection. On the third day post infection, except in the brain, the virus could be isolated from all organs (lung, heart, kidney, liver, and spleen). On the seventh day post infection, the virus could be detected in all six organs. Brain infection was detected in all mice, and the viral titre in the heart, kidney, and spleen infection was high. Conclusion Acute diffuse lung injury was the initial pathogenesis in highly pathogenic H7N9 virus infection. In addition to lung infection and viremia, the highly pathogenic H7N9 virus could cause multiple organ infection and injury.

Identification of cytochrome c oxidase subunit 4 isoform 1 as a positive regulator of influenza virus replication

“…BALB/c mice (female, 6–8 weeks old, 16–18 g) were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing HFK Bioscience Co. Ltd., China) and bred in BSL-3 facilities at South China Agriculture University (China). This animal strain is widely used in the study of AIV infection ( Sang et al, 2021 ; Wu et al, 2021 ). The mice were housed under controlled temperature, humidity, and lighting (23°C ± 1°C; 12: 12 h light–dark cycle) conditions and provided with free access to food and sterile water.…”

Immune Control of Avian Influenza Virus Infection and Its Vaccine Development

“…Aging causes immunosenescence in the innate and adaptive immunological systems, which reduces the body’s ability to respond to the influenza infection and vaccination [ 120 ]. Some of the clinical and pathological characteristics of the severe A/H7N9 sickness brought on by the AIV infections included leukopenia, lymphopenia, viral spread in extra-pulmonary locations, extended viral discharge of H7N9 viral RNA in feces and urine, and multiple organ failure [ 121 , 122 ]. Indeed, in patients with H5N1 infection, large virus levels were also linked to death [ 123 ], while a reduced viral load during the latest H7N9 epidemic was linked to recuperation [ 2 ].…”

Morphological Characteristics of Lungs in Laboratory Balb/C Mice

“…Важливість морфологічного опису легень миші пояснюється тим, що численні моделі індукованої інфекційної [15,23,24,49], алергічної [7,12,30], токсичної патології, захворювань та їх лікування [25,28,37] має обов'язкові прояви саме в дихальній системі. При цих експериментальних дослідженнях виконується оцінка легень мишей, яка не відповідає оцінці легень людини, має інші закономірності та морфологічні особливості.…”