Influenza virus infection is not affected by serum amyloid P component.
BACKGROUND
Binding of serum amyloid P component (SAP) to its ligands, including bacteria, chromatin and amyloid fibrils, protects them from degradation, is anti-opsonic and anti-immunogenic. SAP thereby enhances the virulence of pathogenic bacteria to which it binds. However SAP also contributes to host resistance against bacteria to which it does not bind. Human SAP has been reported to bind to the influenza virus and inhibit viral invasion of cells in tissue culture. We therefore investigated a possible role of SAP in either host resistance or viral virulence during influenza infection in vivo.


METHODS
The clinical course of mouse adapted influenza virus infection, the host antibody response, and viral replication, were compared in wild type mice, mice with targeted deletion of the SAP gene, and mice transgenic for human SAP. The effects of reconstitution of SAP deficient mice with pure human SAP, and of a drug that specifically blocks SAP binding in vivo, were also studied. Binding of mouse and human SAP to immobilized influenza virus was compared.


RESULTS
The presence, absence, or availability for binding of SAP in vivo had no significant or consistent effect on the course or outcome of influenza infection, or on either viral replication or the anti-viral antibody response. Mouse SAP bound much less avidly than human SAP to influenza virus.


CONCLUSIONS
In marked contrast to the dramatic effects of SAP deficiency on host resistance to different bacterial infections, mouse SAP apparently plays no significant role during infection of mice with influenza virus. Human SAP binds much more avidly than mouse SAP to the virus, but also had no effect on any of the parameters measured and is therefore unlikely to be involved in human influenza infection.
Herbert
Jeff
J
Department of Medicine, Royal Free and University College Medical School, London, UK.
Hutchinson
Winston L
WL
Carr
Jackie
J
Ives
Jane
J
Jakob-Roetne
Roland
R
Yamamura
Ken-Ichi
K
Suzuki
Misao
M
Pepys
Mark B
MB
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D002264:Carboxylic Acids / Q000494:pharmacology; D006387:Hemagglutination, Viral / Q000187:drug effects; D006801:Humans; D009980:Influenza A virus / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D007251:Influenza, Human / Q000276:immunology / Q000821:virology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011485:Protein Binding / Q000187:drug effects; D011759:Pyrrolidines / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D000683:Serum Amyloid P-Component / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013045:Species Specificity
D000914:Antibodies, Viral; D002264:Carboxylic Acids; D011759:Pyrrolidines; C455899:R-1-(6-(R-2-carboxypyrrolidin-1-yl)-6-oxohexanoyl)pyrrolidine-2-carboxylic acid; D011993:Recombinant Fusion Proteins; D000683:Serum Amyloid P-Component