Viral infection modulation and neutralization by camelid nanobodies

Proc Natl Acad Sci U S A. 2013 Apr 9;110(15):E1371-9. doi: 10.1073/pnas.1301336110. Epub 2013 Mar 25.


Lactococcal phages belong to a large family of Siphoviridae and infect Lactococcus lactis, a gram-positive bacterium used in commercial dairy fermentations. These phages are believed to recognize and bind specifically to pellicle polysaccharides covering the entire bacterium. The phage TP901-1 baseplate, located at the tip of the tail, harbors 18 trimeric receptor binding proteins (RBPs) promoting adhesion to a specific lactococcal strain. Phage TP901-1 adhesion does not require major conformational changes or Ca(2+), which contrasts other lactococcal phages. Here, we produced and characterized llama nanobodies raised against the purified baseplate and the Tal protein of phage TP901-1 as tools to dissect the molecular determinants of phage TP901-1 infection. Using a set of complementary techniques, surface plasmon resonance, EM, and X-ray crystallography in a hybrid approach, we identified binders to the three components of the baseplate, analyzed their affinity for their targets, and determined their epitopes as well as their functional impact on TP901-1 phage infectivity. We determined the X-ray structures of three nanobodies in complex with the RBP. Two of them bind to the saccharide binding site of the RBP and are able to fully neutralize TP901-1 phage infectivity, even after 15 passages. These results provide clear evidence for a practical use of nanobodies in circumventing lactococcal phages viral infection in dairy fermentation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody Specificity
  • Binding Sites
  • Camelids, New World
  • Crystallography, X-Ray
  • Epitopes / chemistry
  • Fermentation
  • Lactococcus lactis / virology*
  • Microscopy, Electron
  • Models, Molecular
  • Molecular Conformation
  • Nanotechnology
  • Protein Structure, Tertiary
  • Single-Domain Antibodies / chemistry*
  • Siphoviridae / physiology*
  • Surface Plasmon Resonance
  • Viral Tail Proteins / chemistry*


  • Epitopes
  • Single-Domain Antibodies
  • Viral Tail Proteins

Associated data

  • PDB/4HEM
  • PDB/4HEP
  • PDB/4IOS