Formulation, characterization, and expression of a recombinant MOMP Chlamydia trachomatis DNA vaccine encapsulated in chitosan nanoparticles

Abstract

Chlamydia trachomatis is a bacterial sexually transmitted infection affecting millions of people worldwide. Previous vaccination attempts have employed the recombinant major outer membrane protein (MOMP) of C. trachomatis nonetheless, with limited success, perhaps, due to stability, degradation, and delivery issues. In this study we cloned C. trachomatis recombinant MOMP DNA (DMOMP) and encapsulated it in chitosan nanoparticles (DMCNP) using the complex coacervation technique. Physiochemical characterizations of DMCNP included transmission and scanning electron microcopy, Fourier transform infrared and ultravioletvisible spectroscopy, and zeta potential. Encapsulated DMOMP was 167-250 nm, with a uniform spherical shape and homogenous morphology, and an encapsulation efficiency . 90%. A slow release pattern of encapsulated DMOMP, especially in acidic solution, was observed over 7 days. The zeta potential of DMCNP was ∼8.80 mV, which indicated that it was highly stable. Toxicity studies of DMCNP (25-400 µg/mL) to Cos-7 cells using the MTT assay revealed minimal toxicity over 24-72 hours with .90% viable cells. Ultra-violet visible (UV-vis) spectra indicated encapsulated DMOMP protection by chitosan, whereas agarose gel electrophoresis verified its protection from enzymatic degradation. Expression of MOMP protein in DMCNPtransfected Cos-7 cells was demonstrated via Western blotting and immunofluorescence microscopy. Significantly, intramuscular injection of BALB/c mice with DMCNP confirmed the delivery of encapsulated DMOMP, and expression of the MOMP gene transcript in thigh muscles and spleens. Our data show that encapsulation of DMOMP in biodegradable chitosan nanoparticles imparts stability and protection from enzymatic digestion, and enhances delivery and expression of DMOMP in vitro and in mice. Further investigations of the nanoencapsulated DMCNP vaccine formulation against C. trachomatis in mice are warranted.

Poly(lactic acid)–poly(ethylene glycol) nanoparticles provide sustained delivery of a Chlamydia trachomatis recombinant MOMP peptide and potentiate systemic adaptive immune responses in mice

“…The morphology of nanoparticles was assessed using SEM (Zeiss EVO 50 VPSEM) and TEM (Zeiss EM10 TEM) as recently published 16–18 . For SEM, nanoparticles were mounted on metal pegs using conductive double-sided tape and sputter coated with a gold layer prior to examination.…”

“…The mean sizes and zeta potentials of nanoparticles were measured using a zetasizer Nano-ZS instrument (Malvern Instruments, UK) 16–18 . Each nanoparticle sample was measured in triplicates.…”

“…Chemical analyses of the functional groups present in nanoparticles were determined using FT-IR 16,18 . The spectra were obtained with 64 scans per sample ranging from 4000 to 500 cm-1 and a resolution of 4 cm-1.…”

Genital Chlamydia trachomatis: Understanding the Roles of Innate and Adaptive Immunity in Vaccine Research

“…Two recent studies using recombinant MOMP encapsulated in PLGA demonstrated enhanced induction of Th1 cytokines and cellular and antibody immune responses (189,190). Cambridge et al demonstrated that MOMP was expressed in the tissues and organs of mice that were intramuscularly injected with chitosan nanoparticles containing recombinant MOMP DNA (191).…”

Nanomedicine in the management of microbial infection – Overview and perspectives

“…Mice vaccinated with the nanoparticle-detained toxin showed superior protective immunity against toxin-mediated adverse effects; effective virulence neutralization of toxins and 100% survival rate were achieved. Moreover, natural polymers such as chitosan and pullulan have also been utilized for delivery of antigen against bacteria such as C. trachomatis and Streptococcus pneumoniae [172,173]. Interestingly, chitosan was also reported to have adjuvant properties through the promotion of cytokine production.…”