Pilin Vaccination Stimulates Weak Antibody Responses and Provides No Protection in a C57Bl/6 Murine Model of Acute Clostridium difficile Infection

Abstract

Clostridium difficile is the leading cause of nosocomial infections in the United States, adding billions of dollars per year to health care costs. A vaccine targeted against the bacterium would be extremely beneficial in decreasing the morbidity and mortality caused by C. difficile-associated disease; a vaccine directed against a colonization factor would hinder the spread of the bacterium as well as prevent disease. Type IV pili (T4Ps) are extracellular appendages composed of protein monomers called pilins. They are involved in adhesion and colonization in a wide variety of bacteria and archaea, and are putative colonization factors in C. difficile. We hypothesized that vaccinating mice with pilins would lead to generation of anti-pilin antibodies, and would protect against C. difficile challenge. We found that immunizing C57Bl/6 mice with various pilins, whether combined or as individual proteins, led to low anti-pilin antibody titers and no protection upon C. difficile challenge. Passive transfer of anti-pilin antibodies led to high serum anti-pilin IgG titers, but to undetectable fecal anti-pilin IgG titers and did not protect against challenge. The low antibody titers observed in these experiments may be due to the particular strain of mice used. Further experiments, possibly with a different animal model of C. difficile infection, are needed to determine if an anti-T4P vaccine would be protective against C. difficile infection.

Immunoinformatics Approach Toward the Introduction of a Novel Multi-Epitope Vaccine Against Clostridium difficile

“…Additionally, the protective efficacy of C. difficile spore proteins was also investigated (29). However, the general of these vaccination candidates failed to generate a satisfactory immunity (15,17,18,29,35). The protective efficiency of candidate vaccines designed with a single protein is limited.…”

“…(13) found that toxin-based vaccines have no effect on C. difficile colonization or spore spreading from the host to the environment but may lead to an increased number of asymptomatic carriers (13,14). Considering these limitations, several passive immunotherapies against CDI (15,16) targeting other pathogenic factors, such as flagellum, S-layer proteins (SLPs), Cell wall protein 84 (Cwp84), CD0873, Pilin, and spore proteins, have been taken into consideration. However, some of these vaccine candidates failed to induce a sufficient level of immunity and provided only partial protection against CDI-related death (15,(17)(18)(19).…”

Clostridioides difficile infection in the allogeneic hematopoietic cell transplant recipient

“…87,88 For this reason, new passive immunotherapies that target different pathogenic factors, such as pilin, spore proteins, flagellum, and S-layer proteins, are being explored. [89][90][91]…”

“…Toxin‐based vaccines do not prevent CD colonization and cannot restrain the spread of spores from the host to the environment, resulting in a possible increase of asymptomatic carriers 87,88 . For this reason, new passive immunotherapies that target different pathogenic factors, such as pilin, spore proteins, flagellum, and S‐layer proteins, are being explored 89–91 …”

Targeting Clostridium difficile Surface Components to Develop Immunotherapeutic Strategies Against Clostridium difficile Infection

“…More recently these authors immunized mice with various pilins, whether combined or as individual proteins. Unfortunately, “low anti-pilin antibody titers and no protection upon C. difficile challenge were observed” ( Maldarelli et al, 2016 ).…”