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A. Poltorak is the first-listed author of a1998 study connecting altered lipopolysaccharide responses in two mouse strains to mutations in the mouse Tlr4 gene. The gene encodes Toll-like receptor 4, a component of the host response to bacterial material. The verified indexed byline is A. Poltorak; no expanded given name is inferred here.^[ref]

The comparison made two forms of evidence meet. The C3H/HeJ strain had an altered coding sequence, whereas C57BL/10ScCr had a mutation eliminating normal receptor function. Both had impaired lipopolysaccharide signalling. Their relative resistance to endotoxin accompanied increased susceptibility to Gram-negative bacterial infection.^[ref]

The contrast is scientifically important: reduced response to a bacterial product is not automatically improved defence against the bacterium. Linking inherited variation to a molecular receptor helps distinguish recognition of a stimulus from the many downstream consequences of an immune response. The study's host-genetic comparison therefore supplied more information than testing whether a purified substance was inflammatory in one uncharacterized animal.

The mouse Tlr4 gene is the house mouse gene encoding Toll-like receptor 4. NCBI identifies it as Tlr4, GeneID21898. The DNA locus, its RNA transcripts and its receptor protein are distinct objects: measuring a sequence change does not directly measure receptor abundance or signalling output.^[ref]

A1998 study linked two inherited defects in lipopolysaccharide responsiveness to the mouse Tlr4 gene. In C3H/HeJ mice, the coding change was predicted to replace proline by histidine at receptor position712. C57BL/10ScCr mice carried a mutation eliminating normal receptor function. These animals were relatively resistant to endotoxin while being unusually susceptible to Gram-negative infection.^[ref]

The result motivates a distinction between avoiding an inflammatory response and recognizing an invading bacterium. A lower response to an isolated bacterial component can coexist with impaired defence against infection. It also illustrates the evidence needed to connect genotype and mechanism: association of a mutation with a phenotype, prediction of its protein consequence and measurement of cellular signalling are related steps, rather than interchangeable assays. The1998 host-genetic findings supported a role for Toll-like receptor 4 in lipopolysaccharide recognition and signalling; a coding variant alone is not a direct ligand-binding measurement.