Parenteral–Oral Immunization with Plant-Derived HBcAg as a Potential Therapeutic Vaccine against Chronic Hepatitis B

Abstract

Chronic hepatitis B (CHB) is the cause of severe liver damage, cirrhosis, and hepatocellular carcinoma for over 240 million people worldwide. Nowadays, several types of treatment are being investigated, including immunotherapy using hepatitis B core antigen (HBcAg) assembled into highly immunogenic capsid-like particles (CLPs). Immunogenicity of plant-produced and purified HBcAg, administered parenterally or intranasally, was previously reported. In this study, a novel parenteral–oral vaccination scheme is proposed using plant-derived HBcAg preparations. The antigen for injection was obtained via transient expression in Nicotiana benthamiana. HBcAg-producing transgenic lettuce was lyophilized and used as an orally delivered booster. The intracellular location of plant-produced HBcAg CLPs implies additional protection in the digestive tract during oral immunization. BALB/c mice were intramuscularly primed with 10 µg of the purified antigen and orally boosted twice with 5 or 200 ng of HBcAg. A long-lasting and significant systemic response after boosting with 200 ng HBcAg was induced, with anti-HBc titer of 25,000. Concomitantly, an insignificant mucosal response was observed, with an S-IgA titer of only 500. The profile of IgG isotypes indicates a predominant Th1 type of immune response, supplemented by Th2, after injection–oral vaccination. The results demonstrate that a low dose of parenteral–oral immunization with plant-derived HBcAg can elicit a specific and efficient response. This study presents a potential new pathway of CHB treatment.

Leaf infiltration in plant science: old method, new possibilities

“…Russet Burbank, S. tuberosum cv. Shepody—TALENs targeted to endogenous starch branching enzyme and an acid invertase [ 78 ] Dendrobium catenatum Lindl.—GFP, GUS [ 36 ] Glycine max, N. benthamiana , GUS [ 84 ] Generation of transiently transformed leaf tissues or genome edition to create plant bioreactors capable of producing recombinant proteins with potential utility, e.g., in medicine, industry, agriculture N. benthamiana ΔXT/FT—ACE2-Fc fusion protein consisting of the Angiotensin-Converting Enzyme 2 (ACE2)—the primary host cell receptor for SARS-CoV-2 binding and the fragment crystallizable (Fc) of human IgG [ 96 ] N. benthamiana —capsid protein of hepatitis B virus; HBc [ 80 ] N. benthamiana —SARS-CoV-2 receptor binding domain (RBD), spike specific monoclonal antibody CR3022 [ 97 ] N.benthamiana —mAbs B38 and H4 neutralizing SARS-CoV-2 [ 98 ] N. benthamiana —ΔXT/FT—cooexpression of component proteins of Human IgA Isotypes [ 90 , 101 ] N. benthamiana —hepatitis B core antigen (HBcAg) [ 81 ] N. tabacum, L. cylindrica —codon optimised human deoxiribonuclease I; (Dnase I) [ 54 ] N. benthamiana —GRFT, SP-D, CV-N, hMBL, galectin-9 [ 92 ] N. benthamiana —the recombinant sIgA1 was either expressed alone or co-infiltrated with the vectors carrying genes encoding the proteins for N -glycan modification or mucin-type O -glycosylation [ 56 ] Plant biotechnology, nanobiotechnology Generation of nanobionic plants to improve their natural functions or give new properties ...…”

Plant-Derived Human Vaccines: Recent Developments

“…In the last 5 years, more recent studies have looked at the use of HBcAg expression in plants as a therapeutic vaccine [ 87 ]. Pyrski et al [ 88 ] have recently reported the parenteral immunisation of mice with HBcAg produced transiently in N. benthamiana with an oral boost of HBcAg-expressing lettuce. The low dose elicited a specific high titre antibody response with a predominant Th1 response and evidence of a Th2 response after the oral boost.…”

Producing Vaccines against Enveloped Viruses in Plants: Making the Impossible, Difficult

“…In these and other studies, protein accu- In addition to HBsAg, particles of the HBV core antigen, HBcAg, have been produced in plants, initially through stable transgenesis but subsequently mainly via transient expression [27,[30][31][32]. Although such particles can potentially form the basis of vaccines against HBV [33], they have mainly been deployed as a method of presenting foreign antigenic sequences, including those from enveloped viruses such as dengue virus [34][35][36]. These applications are discussed in the section dealing with flaviviruses (Section 8 below).…”