Abstract:

【Objective】 To investigate whether HCAbs (heavy chain antibodies ) discovered in Camelus bactrianus consist of only two heavy chains possess the same biological activity as conventional antibodies. 【Method】 A recombinant expression vector pGEX4T-1-spaA-N which constructed previously and contained insert gene derived from surface protective antigen of Erysipeolothrix rhusiopathiae was induced and the recombinant GST-spaA-N was expressed. One bactrian camel was immunized with purified recombinant antigen GST-SpaA-N, and the anti-SpaA-N IgGs fractions were obtained via protein G and protein A chromatography. The antigen specificity and binding activity of polyclonal HCAbs were analyzed with western blotting and ELISA.【Result】 IgG2 HCAb was successfully isolated from camel sera. The Protein A/G eluted fraction revealed that HCAbs might on the percentages of 60%-80% of total IgG. The immunized camel was at least induced high titer IgG2 by SpaA-N, reached 1:51 200 on day 70. The isolated polyclonal IgG2 HCAb could bind SpaA specifically in western blotting. The result of ELISA showed the IgG2 HCAbs bear the same biological antigen binding activity as conventional ones. 【Conclusion】 The polyclonal HCAbs with the same antigen binding activity was isolated from a bactrian camel sera for the first time, indicating its important role in camel immune protection.

Key words: camelus bactrianus, antigen specificity, HCAb, isolation