Antibodies targeted to fungal cell wall polysaccharides

Abstract

A compound comprising one or more polysaccharide moieties each independently represented by the formula β(1→4)-[GlcNH—R] n -2,5-anhydromannose, wherein n is a positive integer from 3 to 500, and R is H or an acyl group, is described. The compound can be manufactured by (a) reacting chitosan with an acylating agent sufficient to partially N-acylate the chitosan, yielding a modified chitin/chitosan mixed polymer; and (b) reacting the modified chitin/chitosan mixed polymer with a deaminating agent to cleave the mixed polymer at the unacylated chitosan moieties. The compound can be used to immunize against fungal infection. Antibodies specific to the compound, and the use of such antibodies to protect against fungal infection are also described.

1 . A compound comprising one or more polysaccharide moieties each independently represented by the formula β(1→4)-[GlcNH—R] n -2,5-anhydromannose, wherein n is a positive integer from 3 to 500, and R is H or an acyl group. 
     
     
         2 . The compound of  claim 1 , wherein n is a positive integer from 3 to 100. 
     
     
         3 . The compound of  claim 2 , wherein n is a positive integer from 6 to 50. 
     
     
         4 . The compound of  claim 1 , wherein the acyl group R is an acetyl group. 
     
     
         5 . The compound of  claim 1 , wherein at least 30% of the acyl groups in the compound are acetyl. 
     
     
         6 . The compound of  claim 1 , further comprising a carrier protein covalently linked to the one or more polysaccharide moieties. 
     
     
         7 . The compound of  claim 6 , wherein the carrier protein is selected from the group consisting of tetanus toxoid, diphtheria toxoid, and a fungal protein virulence factor. 
     
     
         8 . The compound of  claim 6 , wherein the carrier protein is covalently linked directly to the one or more polysaccharide moieties at the anhydromannose group of each of the polysaccharide moieties. 
     
     
         9 . The compound of  claim 6 , wherein the carrier protein is covalently linked to the one or more polysaccharide moieties via one or more immunogenic scaffold moieties. 
     
     
         10 . The compound of  claim 9 , wherein each of the scaffold moieties is selected from the group consisting of a polysaccharide, a peptidoglycan, a polypeptide, and a polyglycerol. 
     
     
         11 . The compound of  claim 9 , wherein the scaffold is linear. 
     
     
         12 . The compound of  claim 9 , wherein the scaffold is dendrimeric. 
     
     
         13 . The compound of  claim 6  or  12 , further comprising one or more linear β-mannan or glucan epitopes covalently linked to the carrier protein or the scaffold. 
     
     
         14 . The compound of  claim 13 , wherein the β-mannan is a β-1,2-mannose tetrasaccharide. 
     
     
         15 . The compound of  claim 13 , wherein one of the one or more glucan epitopes is a linear α-1,3-glucan epitope. 
     
     
         16 . The compound of  claim 13 , wherein one of the one or more glucan epitopes is a linear β-1,3-glucan epitope. 
     
     
         17 . A composition comprising the compound of any one of  claims 1  to  16 , wherein for at least 80% of molecules of the compound in the composition n has a value from 6 to 50. 
     
     
         18 . A composition comprising the compound of any one of  claims 1  to  16 , wherein the mean value of n is from 10 to 50. 
     
     
         19 . A process for manufacturing a compound represented by the formula μ(1→4)-[GlcNH—R] n 2,5-anhydromannose, wherein n is a positive integer from 3 to 500, comprising:
 (a) reacting chitosan with an amount of an acylating agent sufficient to partially N-acylate the chitosan, yielding a modified chitin/chitosan mixed polymer; 
 (b) reacting the modified chitin/chitosan mixed polymer with a deaminating agent to cleave the mixed polymer at the unacylated chitosan moieties, yielding the compound of formula μ(1→4)-[GlcNH—R] n -2,5-anhydromannose. 
 
     
     
         20 - 24 . (canceled) 
     
     
         25 . A method of immunizing a mammalian subject against a fungal pathogen, comprising administering to the subject an immunogenic amount of the compound or composition of any one of  claims 1  to  18 . 
     
     
         26 . The method of  claim 25 , wherein the subject is a human subject. 
     
     
         27 . An antibody specific to the compound of any one of  claims 1  to  5 . 
     
     
         28 . A method of protecting a mammalian subject against a fungal infection, comprising administering to the subject an antibody specific to the compound or composition of any one of  claim 1  to  5 ,  17 , or  18 , in an amount effective to protect the subject against the fungal infection.