Biology subjects

Ballard, J. D.

Publications and source records attributed to Ballard, J. D..

2 recordsLinked to original sources

bioRxiv2025

Human C. difficile-specific memory B cells encode protective IgG1 despite predominance of non-neutralizing antibodies.

Clostridioides difficile remains a common source of nosocomial infection resulting in a wide range of clinical outcomes and for which there is no vaccine and limited therapeutic options. C. difficile Toxin B (TcdB)-specific IgG is the best correlate of protection against severe and recurrent disease. However, there are very few therapeutic IgG fully human monoclonal antibodies (hmAbs) that have shown efficacy thus far. We therefore hypothesized that the memory B cell (Bmem) compartment of individuals who have recovered from infection may be dominated by non-protective IgG molecules but encode some antibodies that are protective. We therefore produced hmAbs from a library of Bmem-encoded IgG1 sequences. Most TcdB-specific hmAbs displayed low affinity binding and poor neutralization of TcdB in vitro while a few hmAbs had high affinity binding and good TcdB neutralization. The results correlated with in vivo studies in which high affinity, TcdB-neutralizing hmAbs provided moderate protection of C57Bl/6 mice against C. difficile disease. Similar protection was observed in Tg32 mice expressing the human FcRn transgene, indicating that gut delivery of hmAb did not account for limited efficacy. Although non-protective antibody sequences dominate the repertoire, human Bmem cells may be a good source of therapeutic hmAbs for C. difficile treatment.

immunology↗

bioRxiv2021

Loss of ClpP Function in Clostridioides difficile 630 Significantly Impacts Sporulation Systems

The Gram-positive bacterium Clostridioides difficile is a primary cause of hospital-acquired diarrhea, threatening both immunocompromised and healthy individuals. An important aspect of elucidating mechanisms that drive C. difficile persistence and virulence relies on developing a more complete understanding of sporulation. C. difficile sporulation is the single determinant of transmission and complicates treatment and prevention due to the chemical and physical resilience of spores. Hence, the identification of potentially druggable targets that significantly attenuate sporulation is important. In this report, we describe the impact of the loss of caseinolytic protease P (ClpP) isoforms in C. difficile strain 630 on sporulation phenotypes. Using CRISPR-Cas9 nickase mediated genome editing, stop codons were inserted early in the coding sequence for clpP1 and clpP2 to generate C. difficile mutants that no longer produced ClpP1 or ClpP2. The data show that these genetic modifications lead to altered sporulation phenotypes, germination efficiencies, and cytotoxicity. Comparative proteome profiling of C. difficile 630 WT and clpP mutants reveals potential proteolytic targets of ClpP that are involved in sporulation. These analyses further reveal the potential for preferred co-chaperone interactions for each ClpP isoform. Taken together, our results demonstrate that ClpP, a promising target in other Gram-positive pathogens, holds promise as an anti-sporulation target in C. difficile.

microbiology↗