Natural IgM antibodies in baby rabbit serum bind high-mannose glycans on HIV type 1 glycoprotein 120/160 and activate classic complement pathway.
Serum from rodents and felines has been found very effective in complement-dependent lysis of HIV-1, even in nonimmunized animals, but the effector molecules in animal serum and target structures on HIV-1 envelope gp120/160 responsible for complement activation were not determined. We have found that the natural anti-carbohydrate-specific IgM antibodies present in baby rabbit serum were able to lyse effectively the CD4+ T cells coated with the whole virus or with a recombinant gp120/160, irrespectively of the virus strain or glycoprotein expression system. When the high mannose-type glycans on gp160 were enzymatically removed by endoglycosidase F or blocked with the specific lectins, the complement activation and subsequent cell lysis were abolished. IgM-depleted baby rabbit serum was not able to lyse the gp120/160- and/or whole virus-coated target cells. These results suggest that the target structures for complement-activating and naturally occurring IgM antibodies in baby rabbit serum are high-mannose residues on HIV-1 envelope glycoprotein.
Gerencer
M
M
Biomedical Research Center, Immuno AG, Orth/Donau, Austria.
Barrett
P N
PN
Kistner
O
O
Mitterer
A
A
Dorner
F
F
D000818:Animals; D000831:Animals, Newborn; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D016466:CHO Cells; D002460:Cell Line; D003167:Complement Activation / Q000276:immunology*; D006224:Cricetinae; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000276:immunology*; D019302:HIV Envelope Protein gp160 / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D008358:Mannose / Q000276:immunology*; D011134:Polysaccharides / Q000276:immunology*; D011817:Rabbits; D012756:Sheep
D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D019302:HIV Envelope Protein gp160; D007075:Immunoglobulin M; D011134:Polysaccharides; D008358:Mannose