For instance, full length chimeric molecules containing the N-terminus and collagen domains of SP-D connected to the NCRD of conglutinin or human mannose binding lectin (MBL) have significantly greater neutralizing activity than wild-type SP-D [14, 15]. Furthermore full length trimers

of CL-43, or the CL-43 NCRD have strong antiviral activity [16]. Given that SP-D recognizes high mannose glycans associated with the viral hemagglutinin and the neuraminidase [6], our initial hypothesis was that the same structural adaptations were responsible for the enhanced recognition of mannose-rich oligosaccharides of mannan and IAV by CL-43 [16]. In this paper, we compare antiviral properties of NCRD preparations of SP-D and the serum collectins. We report for the first time strong antiviral activity of the bovine serum collectin

CL-46 NCRD. To further analyse the increased antiviral activity of bovine serum collectins Selleckchem Napabucasin we prepared novel mutant versions of hSP-D-NCRD in which specific residues found in serum collectins replace those of wild-type SP-D. These mutants were then compared for antiviral AZD4547 mw activity and binding to mannan. Finally, we determine interactions of functionally enhancing monoclonal antibodies raised against SP-D with bovine collectin NCRD. Virus preparations.  Influenza A virus was grown in the chorioallantoic fluid of 10-day-old chicken eggs and purified on a discontinuous sucrose gradient as previously described [17]. The virus was dialysed against PBS to remove sucrose, aliquoted and stored at −80 °C until needed. Philippines 82/H3N2 (Phil82) and Brazil78/H1N1 (Braz78) strains and their bovine serum inhibitor resistant variants, Phil82/BS and Braz78/BS, were kindly provided by Dr. E. Margot Anders (University of Melbourne, Melbourne, Australia) [18]. Post-thawing the viral stocks contained approximately 5 × 108 plaque forming units/ml. Collectin preparations.  PAK6 Dodecamers of wild-type recombinant human SP-D were used as control and were expressed in CHO cells and purified as described [19]. Trimeric NCRD fusion proteins, including the wild-type human and rat NCRD (hereafter, called

hSP-D-NCRD and rNCRD, respectively), mutant constructs of the hSP-D-NCRD and rNCRD, and NCRD of other collectins (apart from that of CL-46) were produced in E. coli as described [20, 21]. All fusion proteins contain an identical N-terminal His-tag that facilitates purification. An internal S-protein binding site permits detection using S-protein horseradish peroxidase (HRP), as previously described [21]. All NCRD migrated as a single major band of the appropriate size for trimers on SDS–PAGE with the expected decrease in mobility on reduction, consistent with the formation of normal intrachain disulphide bonds. All showed retention of some or all of the calcium-dependent carbohydrate binding activities of the native protein.