Glucose decoration on wall-teichoic acid is required for phage adsorption and InlB-mediated virulence in Listeria ivanovii

Listeria ivanovii (Liv ) is an intracellular Gram-positive pathogen that primarily infects ruminants, but also occasionally causes enteric infections in humans. Albeit rare, this bacterium possesses the capacity to cross the intestinal epithelium of humans, similar to its more frequently pathogenic cousin,Listeria monocytogenes (Lmo ). Recent studies inLmo have shown that specific glycosyl modifications on the cell wall-associated glycopolymers (termed wall-teichoic acid, or WTA) ofLmo are responsible for bacteriophage adsorption and retention of the major virulence factor, Internalin B (InlB). However, the relationship between InlB and WTA inLiv remains unclear. Here, we report the identification of the unique gene,liv1070 that encodes a putative glucosyltransferase in the polycistronic WTA gene cluster of theLiv WSLC 3009 genome. We found that in-frame deletion ofliv1070 led to loss of the glucose substitution on WTA, as revealed by UPLC-MS analysis. Interestingly, the glucose-deficient mutant became resistant to phage B025 infection due to an inability of the phage to adsorb to the bacterial surface, a binding process mediated by the receptor-binding protein B025_Gp17. As expected, deletion ofliv1070 led to loss of InlB retention to the bacterial cell wall, which corresponded to a drastic decrease in cellular invasion. Genetic complementation ofliv1070 restored the characteristic phenotypes, including glucose decoration, phage adsorption, and cellular invasion. Taken together, our data demonstrate that an interplay between phage, bacteria, and host cells also exists inListeria ivanovii , suggesting the trade-off between phage resistance and virulence attenuation may be a general feature in theListeria genus.Importance Listeria ivanovii is a Gram-positive bacterial pathogen known to cause enteric infection in rodents and ruminants, and occasionally in immunocompromised humans. Recent investigations revealed that, in its better-known cousinListeria monocytogenes , strains develop resistance to bacteriophage attack due to loss of glycosylated surface receptors, which subsequently resulting in disconnection of one of the bacterium's major virulence factors, InlB. However, the situation inL. ivanovii remains unclear. Here, we show thatL. ivanovii acquires phage resistance following deletion of a unique glycosyltransferase. This deletion also leads to dysfunction of InlB, making the resulting strain unable to invade host cells. Overall, this study suggests that the interplay between phage, bacteria and the host may be a feature common to theListeria genus.