Sequence and structure specific antibodies from phage display libraries

Area of Science:

• Molecular Biology
• Immunology
• Biochemistry

Background:

• Phage display technology allows for the selection of antibodies against various targets.
• Nucleic acid-specific antibodies are valuable tools in molecular biology and diagnostics.
• The repertoire of antibodies generated by phage display may vary in specificity and representation.

Purpose of the Study:

• To investigate the feasibility of generating sequence- and structure-specific antibodies against diverse nucleic acid antigens using phage display.
• To characterize the specificity of antibodies derived from panning against different nucleic acid targets.
• To assess the representation of antibody sequences within the phage display library.

Main Methods:

• A large combinatorial phage display library was screened against five nucleic acid antigens: calf thymus DNA, poly[d(GC)], poly[d(AT)], poly(dA) x poly(dT), and poly(rA) x poly(dT).
• Antibody clones were selected through multiple rounds of panning.
• Specificity was evaluated using direct and competitive solid-phase radioimmunoassays.

Main Results:

• Positive clones were obtained against poly[d(GC)], poly(dA) x poly(dT), and poly(rA) x poly(dT) after 3-4 rounds.
• Clones from poly[d(GC)] panning were non-specific, binding to all nucleic acids.
• Clones from poly(rA) x poly(dT) showed specificity for single-stranded nucleic acids with sequence preferences.
• Clones from poly(dA) x poly(dT) exhibited considerable specificity for this antigen.
• No positive clones were detected for poly[d(AT)] after six rounds, and only two for calf thymus DNA after seven rounds.
• Sequences of selected antibodies showed no similarity to known DNA-binding antibodies.

Conclusions:

• Phage display libraries can yield sequence- and structure-specific antibodies against nucleic acids.
• The success of antibody recovery is dependent on the specific nucleic acid antigen.
• The phage display repertoire may not represent all possible antibody sequences, potentially limiting the recovery of antibodies against certain antigens like poly[d(AT)] and calf thymus DNA.