School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, College Road, Loughborough, Leicestershire LE125RD, UK.
BMC Vet Res. 2010 Jan 27;6:4. doi: 10.1186/1746-6148-6-4.
A major determinant of influenza infection is the presence of virus receptors on susceptible host cells to which the viral haemagglutinin is able to bind. Avian viruses preferentially bind to sialic acid alpha2,3-galactose (SAalpha2,3-Gal) linked receptors, whereas human strains bind to sialic acid alpha2,6-galactose (SAalpha2,6-Gal) linked receptors. To date, there has been no detailed account published on the distribution of SA receptors in the pig, a model host that is susceptible to avian and human influenza subtypes, thus with potential for virus reassortment. We examined the relative expression and spatial distribution of SAalpha2,3-GalG(1-3)GalNAc and SAalpha2,6-Gal receptors in the major organs from normal post-weaned pigs by binding with lectins Maackia amurensis agglutinins (MAA II) and Sambucus nigra agglutinin (SNA) respectively.
Both SAalpha2,3-Gal and SAalpha2,6-Gal receptors were extensively detected in the major porcine organs examined (trachea, lung, liver, kidney, spleen, heart, skeletal muscle, cerebrum, small intestine and colon). Furthermore, distribution of both SA receptors in the pig respiratory tract closely resembled the published data of the human tract. Similar expression patterns of SA receptors between pig and human in other major organs were found, with exception of the intestinal tract. Unlike the limited reports on the scarcity of influenza receptors in human intestines, we found increasing presence of SAalpha2,3-Gal and SAalpha2,6-Gal receptors from duodenum to colon in the pig.
The extensive presence of SAalpha2,3-Gal and SAalpha2,6-Gal receptors in the major organs examined suggests that each major organ may be permissive to influenza virus entry or infection. The high similarity of SA expression patterns between pig and human, in particular in the respiratory tract, suggests that pigs are not more likely to be potential hosts for virus reassortment than humans. Our finding of relative abundance of SA receptors in the pig intestines highlights a need for clarification on the presence of SA receptors in the human intestinal tract.
流感感染的一个主要决定因素是易感宿主细胞上存在病毒受体，病毒血凝素能够与之结合。禽病毒优先结合唾液酸α2,3-半乳糖（SAα2,3-Gal）连接的受体，而人类株则结合唾液酸α2,6-半乳糖（SAα2,6-Gal）连接的受体。迄今为止，尚无关于猪中 SA 受体分布的详细报道，猪是一种易感染禽和人流感亚型的模型宿主，因此具有病毒重配的潜力。我们通过分别用凝集素 Maackia amurensis 凝集素（MAA II）和 Sambucus nigra 凝集素（SNA）结合，检测了正常断奶后猪主要器官中 SAα2,3-GalG(1-3)GalNAc 和 SAα2,6-Gal 受体的相对表达和空间分布。
在所检查的主要猪器官（气管、肺、肝、肾、脾、心、骨骼肌、大脑、小肠和结肠）中，广泛检测到 SAα2,3-Gal 和 SAα2,6-Gal 受体。此外，猪呼吸道中两种 SA 受体的分布与已发表的人类呼吸道数据非常相似。在其他主要器官中，猪和人类之间 SA 受体的表达模式相似，但肠道除外。与关于人类肠道中流感受体稀缺的有限报道不同，我们发现猪的肠道从十二指肠到结肠，SAα2,3-Gal 和 SAα2,6-Gal 受体的存在逐渐增加。
在所检查的主要器官中广泛存在 SAα2,3-Gal 和 SAα2,6-Gal 受体表明，每个主要器官都可能允许流感病毒进入或感染。猪和人类之间 SA 表达模式的高度相似，特别是在呼吸道中，表明猪不太可能成为病毒重配的潜在宿主。我们在猪肠道中发现相对丰富的 SA 受体，这突出表明需要澄清人类肠道中 SA 受体的存在。
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