A recombinant DNA and vaccinia virus prime-boost regimen induces potent long-term T-cell responses to HCV in BALB/c mice

Therapeutic strategies and promising vaccine for hepatitis C virus infection

Hepatitis C virus (HCV) infection is still a significant global health problem despite therapeutic advancements. Ribavirin and interferon therapy have been the sole available treatments for HCV infection for a number of years with low efficacy. Thus, currently, a number of therapeutic strategies are being used, including nanoparticles (NPs), micro-RNAs such as small interfering RNA (siRNA), RNAi-based gene silencing and antisense oligonucleotide-based microRNA-122, microRNA-155, and short hairpin RNAs (shRNAs), and immunotherapeutic approaches such as anti-programmed cell death 1(PD-1), monoclonal antibodies (mAb or moAb), and monocyte-derived dendritic cells (Mo-DCs). Furthermore, direct-acting antivirals (DAAs) and host-targeting agents (HTA) were also the current therapeutic approaches with great efficacy. In spite of different clinical trials on HCV vaccine developments, nowadays there is no effective HCV vaccine in opposition to virus due to various challenges including genetic diversity, lack of immunocompetent small animal models, shortage of HCV vaccination testing alternatives, lack of an effective tissue culture method for replicating HCV, and inadequate knowledge regarding to immune responses against HCV infection. Nowadays, mRNA vaccine, recombinant viral vector, peptides vaccine, virus-like particles, DNA vaccine, rational designed vaccine, and recombinant polyantigenic T-cell-based vaccine are novel promising candidates for HCV vaccine based on various clinical trials. This review summarizes the different therapeutic approaches and the advancements of vaccine candidates for HCV infection.

Hepatitis C virus DNA vaccines: a systematic review

BACKGROUND

Vaccination against HCV is an effective measure in reduction of virus-related public health burden and mortality. However, no prophylactic vaccine is available as of yet. DNA-based immunization is a promising modality to generate cellular and humoral immune responses. The objective of this study is to provide a systematic review of HCV DNA vaccines and investigate and discuss the strategies employed to optimize their efficacies.

METHODS

MEDLINE (PubMed), Web of Science, Scopus, ScienceDirect, and databases in persian language including the Regional Information Centre for Science & Technology (RICeST), the Scientific Information Database and the Iranian Research Institute for Information Science and Technology (IranDoc) were examined to identify studies pertaining to HCV nucleic acid vaccine development from 2000 to 2020.

RESULTS

Twenty-seven articles were included. Studies related to HCV RNA vaccines were yet to be published. A variety of strategies were identified with the potential to optimize HCV DNA vaccines such as incorporating multiple viral proteins and molecular tags such as HBsAg and Immunoglobulin Fc, multi-epitope expression, co-expression plasmid utilization, recombinant subunit immunogens, heterologous prime-boosting, incorporating NS3 mutants in DNA vaccines, utilization of adjuvants, employment of less explored methods such as Gene Electro Transfer, construction of multi- CTL epitopes, utilizing co/post translational modifications and polycistronic genes, among others. The effectiveness of the aforementioned strategies in boosting immune response and improving vaccine potency was assessed.

CONCLUSIONS

The recent progress on HCV vaccine development was examined in this systematic review to identify candidates with most promising prophylactic and therapeutic potential.

Protective Efficacy of the Conserved NP, PB1, and M1 Proteins as Immunogens in DNA- and Vaccinia Virus-Based Universal Influenza A Virus Vaccines in Mice

The conventional hemagglutinin (HA)- and neuraminidase (NA)-based influenza vaccines need to be updated most years and are ineffective if the glycoprotein HA of the vaccine strains is a mismatch with that of the epidemic strain. Universal vaccines targeting conserved viral components might provide cross-protection and thus complement and improve conventional vaccines. In this study, we generated DNA plasmids and recombinant vaccinia viruses expressing the conserved proteins nucleoprotein (NP), polymerase basic 1 (PB1), and matrix 1 (M1) from influenza virus strain A/Beijing/30/95 (H3N2). BALB/c mice were immunized intramuscularly with a single vaccine based on NP, PB1, or M1 alone or a combination vaccine based on all three antigens and were then challenged with lethal doses of the heterologous influenza virus strain A/PR/8/34 (H1N1). Vaccines based on NP, PB1, and M1 provided complete or partial protection against challenge with 1.7 50% lethal dose (LD50) of PR8 in mice. Of the three antigens, NP-based vaccines induced protection against 5 LD50 and 10 LD50 and thus exhibited the greatest protective effect. Universal influenza vaccines based on the combination of NP, PB1, and M1 induced a strong immune response and thus might be an alternative approach to addressing future influenza virus pandemics.

From lesions to viral clones: biological and molecular diversity amongst autochthonous Brazilian vaccinia virus

Vaccinia virus (VACV) has had an important role for humanity because of its use during the smallpox eradication campaign. VACV is the etiologic agent of the bovine vaccinia (BV), an emerging zoonosis that has been associated with economic, social, veterinary and public health problems, mainly in Brazil and India. Despite the current and historical VACV importance, there is little information about its circulation, prevalence, origins and maintenance in the environment, natural reservoirs and diversity. Brazilian VACV (VACV-BR) are grouped into at least two groups based on genetic and biological diversity: group 1 (G1) and group 2 (G2). In this study, we went to the field and investigated VACV clonal diversity directly from exanthemous lesions, during BV outbreaks. Our results demonstrate that the G1 VACV-BR were more frequently isolated. Furthermore, we were able to co-detect the two variants (G1 and G2) in the same sample. Molecular and biological analysis corroborated previous reports and confirmed the co-circulation of two VACV-BR lineages. The detected G2 clones presented exclusive genetic and biological markers, distinct to reference isolates, including VACV-Western Reserve. Two clones presented a mosaic profile, with both G1 and G2 features based on the molecular analysis of A56R, A26L and C23L genes. Indeed, some SNPs and INDELs in A56R nucleotide sequences were observed among clones of the same virus population, maybe as a result of an increased mutation rate in a mixed population. These results provide information about the diversity profile in VACV populations, highlighting its importance to VACV evolution and maintenance in the environment.

Long-term functional duration of immune responses to HCV NS3/4A induced by DNA vaccination

We have investigated the ability of hepatitis C virus non-structural (NS) 3/4A-DNA-based vaccines to activate long-term cell-mediated immune responses in mice. Wild-type and synthetic codon optimized (co) NS3/4A DNA vaccines have previously been shown to be immunogenic in mice, rabbits and humans, although we have very poor knowledge about the longevity of the immune responses primed. We therefore analyzed the functionality of primed NS3/4A-specific immune responses in BALB/c (H-2^d) and/or C57BL/6J (H-2^b) mice 1, 2, 3, 4, 6, 12 and 16 months after the last immunization. Mice were immunized one, two, three or four times using gene gun delivery to the skin or by intramuscular administration. Immunological responses after immunization were monitored by protection against in vivo challenge of NS3/4A-expressing syngeneic tumor cells. In addition, functionality of the NS3/4A-specific T cells was analyzed by a standard cytotoxicity assay. First, we identified a new unique murine H-2^d-restricted NS3/4A cytotoxic T lymphocyte (CTL) epitope, which enabled us to study the epitope-specific immune responses. Our results show that the coNS3/4A vaccine was highly immunogenic by determination of interferon-γ/tumor necrosis factor-α production and lytic cytotoxic T cells, which could efficiently inhibit in vivo tumor growth. Importantly, we showed that one to four monthly immunizations protected mice from tumor development when challenged up to 16 months after the last immunization. When determining the functionality of NS3/4A-specific T cells in vitro, we showed detectable lytic activity up to 12 months after the last immunization. Thus, NS3/4A-based DNA vaccines activate potent cellular immune responses that are present and function in both BALB/c and C57BL/6J mice up to 12–16 months after the last immunization. The induction of long-term immunity after NS3/4A DNA immunization has not been shown previously and supports the use of NS3/4A in hepatitis C virus vaccine compositions.

Comparison of the replication characteristics of vaccinia virus strains Guang 9 and Tian Tan in vivo and in vitro

Vaccinia virus is widely used as a vector in the development of recombinant vaccines. Vaccinia virus strain Guang 9 (VG9), which was derived from vaccinia virus strain Tian Tan (VTT) by successive plaque-cloning purification, was more attenuated than VTT. In this study, the host cell range and the growth and replication of VG9 were compared with those of VTT. The results showed that both VG9 and VTT could infect permissive cells (Vero, TK-143 and CEF) and semipermissive cells PK (15) and induced a visible cytopathic effect (CPE). Both strains could infect nonpermissive CHO-K1 cells but neither was able to reproduce. The replicative ability of VG9 was a little lower than that of VTT. Additionally, recombinant vaccinia viruses containing a firefly luciferase gene (VG9-L and VTT-L) were constructed, and their expression in vitro and replication and spread in vivo were compared. The expression ability of VG9-L was lower than that of VTT-L. Whole-animal imaging data indicated that VG9-L could reproduce quickly and express the exogenous protein at the site of inoculation, regardless of whether the intramuscular, intracutaneous, subcutaneous or celiac inoculation route was used. VG9-L was better in its ability to express a foreign protein than VTT-L, but the time during which expression occurred was shorter. There was no dissemination of virus in mice inoculated with either strain. In summary, this study demonstrates the possibility of using VG9 for the production of smallpox vaccines or the construction of recombinant vaccinia virus vaccines.

The novel replication-defective vaccinia virus (Tiantan strain)-based hepatitis C virus vaccine induces robust immunity in macaques

The induction of a robust neutralizing antibody (nAb) response is likely to be as essential as specific cell-mediated immunity (CMI) against multiple antigens for the development of effective preventive and therapeutic vaccines against hepatitis C virus (HCV) infection in humans. To date, no data on the immunogenicity of the replication-defective vaccinia virus (derived from the Tiantan strain) (rNTV)-based HCV vaccine in primates have been reported. This study describes in detail the immunogenicity of various vaccine candidates in rhesus macaques, including rNTV-based and replication-defective recombinant adenoviral (rAd)-based HCV vaccines, as well as HCV pseudotyped virus-like particles (HCVpp). Our data showed that rAd-HCV vaccine boosting induced robust CMI, while priming or boosting with HCVpp enhanced the antigen-specific nAb response after rAd-HCV vaccination; however, CMI was not enhanced. Vaccination includes rNTV-HCV priming induced robust antigen-specific antibody, particularly nAbs, and CMI responses. Furthermore, more robust and longer-lasting CMI and higher cytokine levels (both Th1 and Th2 types, especially IFN-γ) resulted from boosting with rAd-HCV. We conclude that the rNTV-based HCV vaccine induces robust nAbs and CMI when combined with a heterogeneous primer-booster strategy, which shows promise for development of a human HCV vaccine.

Induction of broadly neutralising HCV antibodies in mice by integration-deficient lentiviral vector-based pseudotyped particles

Introduction

Integration-deficient lentiviral vectors (IDLVs) are a promising platform for immunisation to elicit both humoral immunity and cellular mediated immunity (CMI). Here, we compared the specific immunity in mice immunised via different regimens (homologous and cocktail) with IDLV-based HCV pseudoparticles (HCVpps) carrying pseudotyped glycoproteins E1E2 and bearing the HCV NS3 gene. Humoral and cell-mediated immune responses were also evaluated after IDLV-HCVpp immunisation combined with heterologous rAd5-CE1E2 priming protocols. Sera from the mice effectively elicited anti-E1, -E2, and -NS3 antibody responses, and neutralised various HCVpp subtypes (1a, 1b, 2a, 3a and 5a). No significant CMI was detected in the groups immunised with IDLV-based HCVpps. In contrast, the combination of rAd5-CE1E2 priming and IDLV-based HCVpp boosting induced significant CMI against multiple antigens (E1, E2, and NS3).

Conclusion

IDLV-based HCVpps are a promising vaccination platform and the combination of rAd5-CE1E2 and IDLV-based HCVpp prime-boost strategy should be further explored for the development of a cross-protective HCV vaccine.

Effect of route of delivery on heterologous protection against HCV induced by an adenovirus vector carrying HCV structural genes

Background

An effective vaccine and new therapeutic methods for hepatitis C virus (HCV) are needed, and a potent HCV vaccine must induce robust and sustained cellular-mediated immunity (CMI). Research has indicated that adenoviral and vaccinia vectors may have the ability to elicit strong B and T cell immune responses to target antigens.

Results

A recombinant replication-defective adenovirus serotype 5 (rAd5) vector, rAd5-CE1E2, and a recombinant Tian Tan vaccinia vector, rTTV-CE1E2, were constructed to express the HCV CE1E2 gene (1-746 amino acid HCV 1b subtype). Mice were prime-immunised with rAd5-CE1E2 delivered via intramuscular injection (i.m.), intranasal injection (i.n.), or intradermal injection (i.d.) and boosted using a different combination of injection routes. CMI was evaluated via IFN-γ ELISPOT and ICS 2 weeks after immunisation, or 16 weeks after boost for long-term responses. The humoral response was analysed by ELISA. With the exception of priming by i.n. injection, a robust CMI response against multiple HCV antigens (core, E1, E2) was elicited and remained at a high level for a long period (16 weeks post-vaccination) in mice. However, i.n. priming elicited the highest anti-core antibody levels. Priming with i.d. rAd5-CE1E2 and boosting with i.d. rTTV-CE1E2 carried out simultaneously enhanced CMI and the humoral immune response, compared to the homologous rAd5-CE1E2 immune groups. All regimens demonstrated equivalent cross-protective potency in a heterologous surrogate challenge assay based on a recombinant HCV (JFH1, 2a) vaccinia virus.

Conclusions

Our data suggest that a rAd5-CE1E2-based HCV vaccine would be capable of eliciting an effective immune response and cross-protection. These findings have important implications for the development of T cell-based HCV vaccine candidates.

Immunization with a low dose of hemagglutinin-encoding plasmid protects against 2009 H1N1 pandemic influenza virus in mice

A vaccine against the novel pandemic influenza virus (2009 H1N1) is available, but several problems in preparation of vaccines against the new emerging influenza viruses need to be overcome. DNA vaccines represent a novel and powerful alternative to conventional vaccine approaches. To evaluate the ability of a DNA vaccine encoding the hemagglutinin (HA) of 2009 H1N1 to generate humoral responses and protective immunity, BALB/c mice were immunized with various doses of 2009 H1N1 HA-encoding plasmid and anti-HA total IgG, hemagglutination inhibition antibodies and neutralizing antibodies were assayed. The total IgG titers against HA correlated positively with the doses of DNA vaccine, but immunization with either a low dose (10 μg) or a higher dose (25-200 μg) of HA plasmid resulted in similar titers of hemagglutination inhibition and neutralizing antibodies, following a single booster. Further, 10 μg plasmid conferred effective protection against lethal virus challenge. These results suggested that the DNA vaccine encoding the HA of 2009 H1N1 virus is highly effective for inducing neutralizing antibodies and protective immunity. DNA vaccines are a promising new strategy for the rapid development of efficient vaccines to control new emerging pandemic influenza viruses.

Sequential immunization with heterologous chimeric flaviviruses induces broad-spectrum cross-reactive CD8+ T cell responses

Flavivirus vaccines based on ChimeriVax technology contain the nonstructural genes of the yellow fever vaccine and the premembrane and envelope genes of heterologous flaviviruses, such as Japanese encephalitis and West Nile viruses. These chimeric vaccines induce both humoral and cell-mediated immunity. Mice were vaccinated with yellow fever, chimeric Japanese encephalitis virus (YF/JE), or chimeric West Nile virus (YF/WN) vaccines, followed by a secondary homologous or heterologous vaccination; the hierarchy and function of CD8(+) T cell responses to a variable envelope epitope were then analyzed and compared with those directed against a conserved immunodominant yellow fever virus NS3 epitope. Sequential vaccination with heterologous chimeric flaviviruses generated a broadly cross-reactive CD8(+) T cell response dependent on both the sequence of infecting viruses and epitope variant. The enhanced responses to variant epitopes after heterologous vaccination were not related to preexisting antibody or to higher virus titers. These results demonstrate that the sequence of vaccination affects the expansion of cross-reactive CD8(+) T cells after heterologous chimeric flavivirus challenge.

Chronic hepatitis C virus infection in children

The importance of hepatitis C viral infection in the health care of children has grown in recent decades. More is now known about the epidemiology of this infection in children and the progression of disease in the pediatric age group, and the treatment options are increasing. In this review, we update readers on the state of our understanding of hepatitis C infection in children, provide the current recommendations for monitoring and treatment, and discuss emerging therapies.

General epidemiological parameters of viral hepatitis A, B, C, and E in six regions of China: a cross-sectional study in 2007

BACKGROUND

Viral hepatitis is a serious health burden worldwide. To date, few reports have addressed the prevalence of hepatitis A, B, C, and E in China. Therefore, the general epidemiological parameters of viral hepatitis remain unknown.

PRINCIPAL FINDINGS

In this cross-sectional study, we performed a serological prevalence analysis of viral hepatitis A, B, C, and E in 8,762 randomly selected Chinese subjects, which represented six areas of China. The overall prevalence of anti-Hepatitis C virus antibody (anti-HCV) was 0.58%, which was much lower than was estimated by WHO. The prevalences of Hepatitis B virus surface antigen (HBsAg), anti-Hepatitis B virus surface protein antibody (HBsAb), and anti-Hepatitis B virus core protein antibody (HBcAb) were 5.84%, 41.31%, and 35.92%, respectively, whereas in the group of subjects less than 5 years old, these prevalences were 1.16%, 46.77%, and 8.69% respectively, which suggests that the Hepatitis B virus (HBV)-carrier population is decreasing, and the nationwide HBV vaccine program has contributed to the lowered HBV prevalence in the younger generation in China. Meanwhile, a large deficit remains in coverage provided by the national HBV immune program. In addition, our data suggested the possibility that HBsAb may not last long enough to protect people from HBV infection throughout life. The overall prevalence of anti-Hepatitis A virus antibody (anti-HAV) and anti-Hepatitis E virus antibody (anti-HEV) were as high as 72.87% and 17.66%, respectively. The indices increased with age, which suggests that a large proportion of Chinese adults are protected by latent infection. Furthermore, the pattern of HEV infection was significantly different among ethnic groups in China.

CONCLUSIONS

Our study provided much important information concerning hepatitis A, B, C, and E prevalence in China and will contribute to worldwide oversight of viral hepatitis.

Hepatitis C virus envelope glycoproteins complementation patterns and the role of the ecto- and transmembrane domains

We separated E1 and E2 of hepatitis C virus (HCV) genotypes 1a, 1b, and 2a into two individual expression plasmids and replaced the transmembrane domains of 1b and 2a E1 and E2 with that of genotype 1a. The complementation features of E1 and E2 as well as the contributions of both the ecto- and transmembrane domains to the formation of the E1E2 complex were evaluated using the HCV pseudoparticle(s) (HCVpp(s)) system. We demonstrated that 1aE2 could not only complement its native 1aE1, but could also complement 1bE1 as well; in genotype 1b, glycoprotein complex formation is primarily dependent on the overall biological characteristics of the intact native E1 and E2; in genotype 2a, although the interaction of intact native E1 and E2 is critical for the formation of the glycoprotein complex, the ectodomain made a greater contribution than that of the transmembrane domain. Our study provides valuable findings regarding HCV E1 and E2 biology and will be of use in both anti-HCV strategy and understanding on the mechanisms of coinfection of different HCV strains.