Chimeric Hepatitis B Core Antigen Particles Containing B- and Th-Epitopes of Human Papillomavirus Type 16 E7 Protein Induce Specific Antibody and T-Helper Responses in Immunised Mice

283

176

Papillomavirus-like particles (VLPs) are a promising prophylactic vaccine candidate to prevent human papillomavirus (HPV) infections and associated epithelial neoplasia. However, they are unlikely to have therapeutic effects because the virion capsid proteins are not detected in the proliferating cells of the infected epithelia or in cervical carcinomas. To increase the number of viral antigen targets for cell-mediated immune responses in a VLP-based vaccine, we have generated stable chimeric VLPs consisting of the L1 major capsid protein plus the entire E7 (11 kDa) or E2 (43 kDa) nonstructural papillomavirus protein fused to the L2 minor capsid protein. The chimeric VLPs are indistinguishable from the parental VLPs in their morphology and in their ability to agglutinate erythrocytes and elicit high titers of neutralizing antibodies. Protection from tumor challenge was tested in C57BL͞6 mice by using the tumor cell line TC-1, which expresses HPV16 E7, but not the virion structural proteins. Injection of HPV16 L1͞L2-HPV16 E7 chimeric VLPs, but not HPV16 L1͞L2 VLPs, protected the mice from tumor challenge, even in the absence of adjuvant. The chimeric VLPs also induced protection against tumor challenge in major histocompatibility class IIdeficient mice, but not in ␤ 2 -microglobulin or perforin knockout mice implying that protection was mediated by class I-restricted cytotoxic lymphocytes. These findings raise the possibility that VLPs may generally be efficient vehicles for generating cellmediated immune responses and that, specifically, chimeric VLPs containing papillomavirus nonstructural proteins may increase the therapeutic potential of VLP-based prophylactic vaccines in humans.Human papillomaviruses (HPVs) that infect the genital tract are associated with human anogenital tract cancer, particularly cervical cancer (reviewed in ref. 1). HPVs are thought to be the primary causative agent in Ͼ90% of cervical cancers (2), with HPV16 being the type most frequently found in these tumors. Approximately 500,000 women develop cervical cancer each year, and 200,000 women die from it, making this disease the second-most common cause of cancer deaths in women worldwide (3).Significant advances have been made recently in the development of a candidate prophylactic vaccine against papillomavirus infections (reviewed in ref. 4). Expression of the papillomavirus major capsid protein, L1, in eukaryotic cells leads to self-assembly into virus-like particles (VLPs) that are morphologically indistinguishable from native virions and present the conformational epitopes required for the induction of high titer neutralizing antisera (5). L2, the minor capsid protein, coassembles with L1 at a ratio of Ϸ1 L2 molecule to 30 L1 molecules (6). Although L2 presents some epitopes that induce the production of neutralizing antiserum (7), most neutralizing antibodies induced by L1͞L2 VLPs recognize L1 determinants (8). Several studies have shown that L1 and L1͞L2 VLP-based vaccines protect animals against high dose experimental pap...

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Chimeric papillomavirus virus-like particles elicit antitumor immunity against the E7 oncoprotein in an HPV16 tumor model

Greenstone

Nieland

Visser

et al. 1998

283

176

“…The core antigen of hepatitis B (HBcAg) in virus-like particles has been constructed to contain a foreign epitope from hepatitis B surface antigen (HBsAg) (16), papillomavirus (18), or Plasmodium falciparum (15). Another approach uses recombinant influenza virus in which epitopes of HIV-1 gp41 (19) or Plasmodium yoelii (17) are incorporated into the hemagglutinin antigen.…”

Section: Discussionmentioning

confidence: 99%

“…It has been previously shown with different virus-based expression systems that a variety of viral particles or virus-like particles can serve as carriers of foreign B cell epitopes within the viral capsid or envelope protein of the viral particle. These epitope carriers resulted in strong B cell responses against the expressed foreign epitopes indicating a usefulness of carrier proteins (14)(15)(16)(17)(18)(19)(20). However, most of these approaches are restricted to incorporation of only short peptides that define epitopes due to the restricted cloning capacity within the carrier proteins.…”

mentioning

confidence: 99%

Rabies virus nucleoprotein as a carrier for foreign antigens

Koser

McGettigan

Tan

et al. 2004

Rabies virus (RV) nucleoprotein (N) tightly encapsidates the genomic and antigenomic RNA of RV to form the viral ribonucleoprotein (RNP) complex. Antigens, such as N, presented in a highly organized structure are sufficient and even desirable to activate B cells to proliferate and produce antibodies. In addition to activating B cells to proliferate, it has been shown that RV N in the RNP complex induces potent T helper cell responses resulting in longlasting and strong humoral immune responses against RV. The possibility to systematically incorporate foreign genes into the genome of RV and produce a recombinant virus allows us to examine whether the immunogenicity of foreign antigens can be enhanced by incorporation into the RV RNP structure. To test this hypothesis we constructed a recombinant RV expressing a RV N-GFP fusion protein. The chimeric N-GFP fusion protein was efficiently expressed and incorporated into RV RNP and virions. Moreover, the recombinant RNP induces a strong humoral immune response against GFP in mice. In contrast, mice inoculated with GFP alone or a combination of wild-type RV RNPs and GFP did not trigger any GFP-specific humoral responses using the same immunization schedule. These data indicate the usefulness of RV-based vectors as killed vaccines against other infectious diseases.nucleocapsid ͉ fusion protein ͉ vaccine R abies virus (RV) is a nonsegmented negative-strand RNA virus within the Rhabdoviridae family (1). The RV genome is Ϸ12 kb in size and encodes five monocistronic mRNAs encoding the nucleocapsid protein (N), phosphoprotein (P), matrix protein (M), the transmembrane glycoprotein (G), and the viral RNA-dependent RNA polymerase (L) (2). The N efficiently and specifically encapsidates the viral RNA to form the ribonucleoprotein (RNP) complex, which provides the template for RNA transcription and replication by the viral polymerase complex, which includes the P and L (3, 4). The RV M bridges the RNP with the cytoplasmic domain of RV G, which is embedded in the host cell-derived viral membrane (5). The extracellular domain of the RV G mediates infection of the host cell (6).Recombinant live-viral vectors expressing foreign antigens efficiently induce potent cellular and humoral immune responses against the expressed antigens. The possibility that RV can be used as an expression vector was shown earlier with the model gene chloramphenicol acetyltransferase, and the results from these studies indicated that foreign genes can be expressed stably in RV (7). The possibility that RV could be used as an HIV-1 vaccine was tested, and it was shown in several studies that the expression of HIV-1 Env or Gag resulted in potent immune responses directed against HIV-1 (8-10). In addition, we demonstrated that RV vaccine vectors tolerate large, multiple foreign genes, up to 6.5 kb, and that live-viral RV vectors with a very low pathogenic potential can be constructed (11). Moreover, our results have indicated that killed RV virions containing foreign glycoproteins such as hepatitis C E2 or H...

“…The technical feasibility of the construction of chimeric HBcAg capsids was demonstrated 10 years ago (28). Several foreign epitopes from hepatitis B virus (16), HIV (29), Papillomavirus (30), and Plasmodium falciparum (31) have been introduced successfully into HBcAg capsids, and immunogenicity of the new epitopes has been demonstrated. Our results here add the following new findings: (i) HBcAg capsids behaved as antigenspecific TI-1 particles comparable to other viruses [as vesicular stomatitis virus, polyoma virus, poliovirus (32,33)] but are different from polyclonal activators such as lipopolysaccharide; (ii) A known TD epitope (in our case from the preS1 domain of HBsAg) could be introduced into TI-1 HBcAg capsids and thereby could be changed into a TI-1 antigen, which induced an early IgM response within 4 days totally independent of T cell priming; (iii) In the case of HBcAg capsids as well as particulate Q␤ phage coats, precise structural requirements allowing repetitive arrangement of the new epitope on the particle surface had to be fulfilled to induce TI antibody responses; for Q␤ Kpn proteins, it was linked to the particulate structure of the phage coat, whereas for the chimeric HBcAg capsid S2-16 an equally long compensatory deletion had to be introduced after the new epitope to retain the overall structural integrity of the particle and to allow the optimal superficial positioning of the epitope on the tips accessible to B cell receptors.…”

Section: Discussionmentioning

confidence: 99%

T cell-independent type I antibody response against B cell epitopes expressed repetitively on recombinant virus particles

Fehr

Skrastiņa

Pumpens

et al. 1998

164

Recombinant viral or virus-like particles offer new tools for vaccine development. This study investigated hepatitis B core antigen (HBcAg) capsids and RNA phage Q␤ coats as carriers of a foreign epitope to induce antibody responses in mice. HBcAg capsids were shown to induce T cell-independent (TI) antibodies. We found that these particles behave as antigen-specific TI type 1 (TI-1) Ag comparable to other rigidly structured viruses. When a 5-aa long epitope of the pre-S1 domain of hepatitis B surface antigen (HBsAg) was introduced into the optimal position of the HBc molecule, it also behaved as a TI-1 Ag. Best efficiency of the antibody response to the foreign epitope was achieved by a compensatory deletion after the epitope to retain the regular structure of the HBcAg capsid with a highly repetitive superficial exposition of the foreign epitope. For recombinant Q␤ phage coats, a much more efficient antibody response to the foreign epitope was achieved when the foreign epitope was expressed repetitively on a particulate derivate of Q␤ phage coats. Thus, recombinant virus particles are suitable vaccine carriers for the introduction of foreign B cell epitopes, if precise structural requirements are fulfilled.