tailieunhanh - Báo cáo khoa học: " Replication of avian, human and swine influenza viruses in porcine respiratory explants and association with sialic acid distribution"

Replication of avian, human and swine influenza viruses in porcine respiratory explants and association with sialic acid distribution | Van Poucke et al. Virology Journal 2010 7 38 http content 7 1 38 VIROLOGY JOURNAL RESEARCH Open Access Replication of avian human and swine influenza viruses in porcine respiratory explants and association with sialic acid distribution Sjouke GM Van Poucke1 John M Nicholls2 Hans J Nauwynck1 Kristien Van Reeth1 Abstract Background Throughout the history of human influenza pandemics pigs have been considered the most likely mixing vessel for reassortment between human and avian influenza viruses AIVs . However the replication efficiencies of influenza viruses from various hosts as well as the expression of sialic acid Sia receptor variants in the entire porcine respiratory tract have never been studied in detail. Therefore we established porcine nasal tracheal bronchial and lung explants which cover the entire porcine respiratory tract with maximal similarity to the in vivo situation. Subsequently we assessed virus yields of three porcine two human and six AIVs in these explants. Since our results on virus replication were in disagreement with the previously reported presence of putative avian virus receptors in the trachea we additionally studied the distribution of sialic acid receptors by means of lectin histochemistry. Human Siaa2-6Gal and avian virus receptors Siaa2-3Gal were identified with Sambucus Nigra and Maackia amurensis lectins respectively. Results Compared to swine and human influenza viruses replication of the AIVs was limited in all cultures but most strikingly in nasal and tracheal explants. Results of virus titrations were confirmed by quantification of infected cells using immunohistochemistry. By lectin histochemistry we found moderate to abundant expression of the human-like virus receptors in all explant systems but minimal binding of the lectins that identify avian-like receptors especially in the nasal tracheal and bronchial epithelium. Conclusions The species barrier that restricts the transmission of influenza viruses from