Airborne spread and infection of a novel swine-origin influenza A (H1N1) virus.

Hongna Zhang,Huili Yang,Xin Li,Mingliang Zhang,Hao Wang,Baozhi Wei,Hongliang Dong,Jing Gao,Qinglei Li,Ruihua Ma,Zhihao Liu,Zengmin Miao,Mingchao Cui,Peiqiang Hou,Xiaoxia Li,Xinxian Li,Tongjie Chai,Yufa Zhou

doi:10.1186/1743-422x-10-204

Abstract

BackgroundThe novel swine-origin influenza A (H1N1) virus (S-O 2009 IV) can cause respiratory infectious diseases in humans and pigs, but there are few studies investigating the airborne spread of the virus. In January 2011, a swine-origin H1N1 epidemic emerged in eastern China that rapidly spread to neighboring farms, likely by aerosols carried by the wind.MethodsIn this study, quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to detect viruses in air samples from pig farms. Based on two aerosol infection models (Pig and guinea pig), we evaluated aerosol transmission and infection of the novel S-O 2009 IV isolate.ResultsThree novel S-O 2009 IV were isolated from the diseased pig. The positive rate and viral loads of air samples were 26.1% and 3.14-5.72 log10copies/m3 air, respectively. In both pig and guinea pig infection models, the isolate (A/swine/Shandong/07/2011) was capable of forming aerosols and infected experimental animals at a range of 2.0-4.2 m by aerosols, but aerosol route was less efficient than direct contact.ConclusionsThe results indicated that S-O 2009 IV is able to be aerosolized by infected animals and to be transmitted to susceptible animals by airborne routes.

Highlights

In April 2009, swine-origin 2009 A (H1N1) influenza viruses (S-O 2009 IV) were found in Mexico and the United States for the first time, and quickly spread throughout the world, presenting a significant threat to public health [1,2]
Antigenicity and sequence analysis of the three strains of H1N1 viruses confirmed that the isolated strain was S-O 2009 IV
Results of air and serum samples The positive rate of 157 air samples collected from the 40 pig farms was 26.1% (41/157) and the virus content range was 4.09-5.72 log10copies/m3 air; hemagglutination and hemagglutination-inhibition (HA-HI) tests showed that the positive rate of serum samples was 28.5% (57/200) and titers were 80–2560

Summary

Introduction

In April 2009, swine-origin 2009 A (H1N1) influenza viruses (S-O 2009 IV) were found in Mexico and the United States for the first time, and quickly spread throughout the world, presenting a significant threat to public health [1,2]. Different from seasonal influenza viruses, humans lack immunity to this new virus, and the virus quickly caused a pandemic [2,3,4,5]. The novel swine-origin influenza A (H1N1) virus (S-O 2009 IV) can cause respiratory infectious diseases in humans and pigs, but there are few studies investigating the airborne spread of the virus. In January 2011, a swine-origin H1N1 epidemic emerged in eastern China that rapidly spread to neighboring farms, likely by aerosols carried by the wind

Methods

Results

Conclusion