Isolation and characterization of two H5N1 influenza viruses from swine in Jiangsu Province of China

Abstract

Pigs are susceptible to infection with both human and avian influenza A viruses and are considered intermediate hosts that facilitate virus reassortment. Although H5N1 virus has spread to a wide range of avian and mammalian species, data about swine H5N1 isolates are scarce. To determine whether Asian H5N1 influenza viruses had been transmitted to pigs, a total of 1,107 nasal swab samples from healthy swine were collected from 2008 to 2009 in Jiangsu province of eastern China. In this survey, two H5N1 viruses A/swine/Jiangsu/1/2008 (JS/08) and A/swine/Jiangsu/2/2009 (JS/09) were isolated and identified. Phylogenetic analysis showed that JS/08 and JS/09 belonged to clade 7 and clade 2.3.4, respectively, and shared over 99.0 % sequence identity with poultry H5N1 isolates of the same clade in China. Receptor specificity analysis also showed that both of the swine H5N1 isolates bound preferentially to avian-type receptors. However, experiments in mammals indicated that JS/09 was moderately pathogenic to mice without prior adaption, whereas JS/08 had limited ability to replicate. Our findings suggest that pigs are naturally infected with avian H5N1 virus and highlight the potential threat to public health due to adaption or reassortment of H5N1 virus in this species.

The Evidence of Clade 7.1 Avian Influenza Virus (H5N1) in Qinghai Lake

“…The Shanxi and Ningxia Provinces are situated within the East Asian flyway migratory bird flyway and the poultry transportation between these provinces and Vietnam was rare, suggesting that the migratory birds might also play an important role for the virus transmission to Qinghai Lake. Our results confirm that the M, NP and which rises a concern for human threat [25].…”

Reverse zoonosis of influenza to swine: new perspectives on the human–animal interface

“…To date, there is evidence of only two full or partial avian influenza viruses successfully adapting to transmit stably in swine: the avian-origin Eurasian H1N1 swine viruses [12] and the avian-origin PB2 and PA segments associated with the triple reassortant viruses that emerged in North American swine in the 1990s [50]. A wide range of avian influenza virus subtypes have transiently infected swine in Asia (H1N1 [61], H3N2 [62], H3N8 [63], H4N1 [64], H4N8 [65], H5N1 [66–68], H5N2 [69], H6N6 [70], H7N2 [71], H9N2 [72–75], H10N5 [76], and H11N6), North America (H1N1 [77], H2N3 [78], H3N3 [77], and H4N6 [79]), and Europe (H1N7 [80]). The detection of avian-swine reassortant H2N3 viruses in swine in 2006 in Missouri, USA raised a particular concern for humans, but also did not sustain viral transmission in swine, and there was no evidence of infection of humans [81].…”

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…The molecular and serological investigations report either active infections (viral RNA) or past exposures (antibodies) in swine samples, respectively. The molecular detection approaches followed by sequencing are largely used for the research focusing on the influenza virus epidemiology [73,78,82,87,94,128,146,150]. [5,37,43,45,46,61,74,88,137,157,171,176,188,191,199,207,215,[219][220][221]241,243,248,250,263,289,290,301,306,307,326,334] IAV, IDV, H1N1, H1N2, H3N2, A(H1N1)pdm09 [45,192,227,282,285,287,302,32...…”

“…The first report of HPAIV strain H5N1 in swine was documented during October 2008-May 2009 when two H5N1 virus isolates were retrieved from apparently healthy swine [78]. The third report of avian-origin H9N2 virus in Chinese swine appeared when 144 apparently healthy swine across four provinces viz., Yunnan, Guangdong, Fujian and Zhejiang were found H9N2 positive over a four-year period during March 2008-March 2012.…”