Abstract
Vaccines can have heterologous effects on the immune system, i.e., effects other than triggering an immune response against the disease targeted by the vaccine. We investigated whether monoclonal antibodies (mAbs) specific for tetanus could cross-react with Chlamydia and confer heterologous protection against chlamydial infection. The capability of two tetanus-specific mAbs, namely mAb26 and mAb51, to prevent chlamydial infection has been assessed: (i) in vitro, by performing a neutralization assay using human conjunctival epithelial (HCjE) cells infected with Chlamydia trachomatis serovar B, and (ii) in vivo, by using a guinea pig model of Chlamydia caviae-induced inclusion conjunctivitis. The mAb26 has been superior in comparison with mAb51 in the prevention of chlamydial infection in HCjE cells. The mAb26 has conferred ≈40% inhibition of the infection, compared to less than 5% inhibition in the presence of the mAb51. In vivo, mAb26 significantly diminished ocular pathology intensity in guinea pigs infected with C. caviae compared to either the mAb51-treated or sham-treated guinea pigs. Our data provide insights that tetanus immunization generates antibodies which induce heterologous chlamydial immunity and promote protection beyond the intended target pathogen.
Highlights
In the first edition of the textbook Vaccines (1988), Stanley Plotkin stated: “The impact of vaccination on the health of the world’s peoples is hard to exaggerate
The best overlap of the tetanus toxin (TeNT) and chlamydial amino acid sequences was observed for the C. trachomatis polymorphic membrane protein C (PmpC) and the major outer membrane protein (MOMP) from C. trachomatis serovar B (MOMP-B)
We have shown that mAb26 cannot completely prevent ocular chlamydial guinea pig infection but can significantly alleviate the intensity of pathology at the peak of the disease
Summary
In the first edition of the textbook Vaccines (1988), Stanley Plotkin stated: “The impact of vaccination on the health of the world’s peoples is hard to exaggerate. Vaccines have saved and are still saving millions of lives on Earth. Vaccination is the finest way of initiating protection against viral and bacterial infections; currently, only 26 vaccines against infectious diseases are licensed. Vaccines against many pathogens such as human immunodeficiency virus, Zika virus, hepatitis C virus, SARS-CoV-2, Chlamydia trachomatis, and Borrelia burgdorferi are still unavailable for a variety of reasons, which include but are not limited to (i) pathogen complexity, (ii) pathogen novelty, (iii) absence of efficient delivery system and adjuvants, (iv) lack of knowledge on the mechanisms of protective immune response induction, (v) lack of relevant/suitable animal models, and (vi) ethical issues for conducting clinical trials [2,3,4,5,6,7].
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