Table 1.

Modifications of SP-D found to increase or broaden antiviral activity for IAV.

SP-D preparation	Modification	Effect on antiviral activity
Full length recombinant human SP-D	Isolation of high molecular weight multimers	Increased activity compared to trimers or dodecamers (57, 70)
Full length chimeric protein	Rat SP-D and conglutinin (NCRD) chimera	Increased activity compared with rat SP-D (69)
Full length chimeric protein	Human SP-D and mannose-binding lectin (NCRD) chimera	Increased activity compared with similarly multimerized human SP-D (68)
NCRD trimer of human SP-D	D325A or D325S mutation	Slight increase in activity compared to wild-type NCRD (76)
NCRD trimer of human SP-D	R343V mutation	Strong increased activity compared with wild-type NCRD (75)
NCRD trimer of human SP-D	D325A(or S) combined with R343V mutation	Increased activity compared to R343V or D325A alone; significant activity vs pandemic H1N1 and H3N2 (77)

IAV, influenza A virus; SP-D, surfactant protein D; NCRD, neck and carbohydrate recognition domain.