Compositions and methods to protect cells by blocking entry of pathogen proteins

A method for screening compounds to identify whether they are potential blocking compounds for inhibiting entry of pathogenic effector proteins into a cell, comprising the steps of:

• providing one or more proteins each of which has one or more motifs which are bound by polar lipids as a prerequisite to translocation;
• exposing a candidate compound to said one or more proteins;
• and
• determining whether said candidate compound binds to said one or more motifs of said one or more proteins, and, if binding occurs, determining that said compound is a potential blocking compound for inhibiting entry of pathogenic effector proteins into a cell,
• wherein said one or more motifs comprises an amino acid sequence BXZ, where
• B is an amino acid selected from arginine, lysine and histidine;
• X is any amino acid and may be present or absent;
• and
• Z is an amino acid selected from leucine, methionine, isoleucine, tryptophan, tyrosine and phenylalanine.

A method for screening compounds to identify whether they are potential blocking compounds for inhibiting entry of pathogenic effector proteins into a cell, comprising the steps of:

• providing one or more polar lipids, each of which binds to one or more motifs of an effector protein as a prerequisite to translocation of said effector protein into said cell;
• exposing a candidate compound to said one or more polar lipids;
• and
• determining whether said candidate compound binds to said one or morepolar lipids, and, if binding occurs, determining that said compound is a potential blocking compound for inhibiting entry of pathogenic effector proteins into said cell,
• wherein said one or more motifs comprises an amino acid sequence BXZ, where
• B is an amino acid selected from arginine, lysine and histidine;
• X is any amino acid and may be present or absent;
• and
• Z is an amino acid selected from leucine, methionine, isoleucine, tryptophan, tyrosine and phenylalanine.

A method of inhibiting entry, into a cell, of a pathogenic effector protein, said entry of said pathogenic effector protein into said cell requiring binding of at least one motif of said effector protein to at least one polar lipid of said cell, comprising the step of

• contacting a substrate which contains or is likely to contain a pathogen comprising said pathogenic effector protein with a blocking compound, said blocking compound being capable of
• i) binding to said at least one motif of said pathogenic effector protein;
• or
• ii) binding to said at least one polar lipid of said cell,
• wherein binding of said blocking compound prevents entry of said pathogenic effector protein into said cell if said pathogen comes into contact with said substrate.