SARS-CoV Spike Proteins Expressed by the Vaccinia Virus Tiantan Strain: Secreted SQ Protein Induces Robust Neutralization Antibody in Mice

Improving Cross-Protection against Influenza Virus Using Recombinant Vaccinia Vaccine Expressing NP and M2 Ectodomain Tandem Repeats

Conventional influenza vaccines need to be designed and manufactured yearly. However, they occasionally provide poor protection owing to antigenic mismatch. Hence, there is an urgent need to develop universal vaccines against influenza virus. Using nucleoprotein (NP) and extracellular domain of matrix protein 2 (M2e) genes from the influenza A virus A/Beijing/30/95 (H3N2), we constructed four recombinant vaccinia virus-based influenza vaccines carrying NP fused with one or four copies of M2e genes in different orders. The recombinant vaccinia viruses were used to immunize BALB/C mice. Humoral and cellular responses were measured, and then the immunized mice were challenged with the influenza A virus A/Puerto Rico/8/34 (PR8). NP-specific humoral response was elicited in mice immunized with recombinant vaccinia viruses carrying full-length NP, while robust M2e-specific humoral response was elicited only in the mice immunized with recombinant vaccinia viruses carrying multiple copies of M2e. All recombinant viruses elicited NP- and M2e-specific cellular immune responses in mice. Only immunization with RVJ-4M2eNP induced remarkably higher levels of IL-2 and IL-10 cytokines specific to M2e. Furthermore, RVJ-4M2eNP immunization provided the highest cross-protection in mice challenged with 20 MLD₅₀ of PR8. Therefore, the cross-protection potentially correlates with both NP and M2e-specific humoral and cellular immune responses induced by RVJ-4M2eNP, which expresses a fusion antigen of full-length NP preceded by four M2e repeats. These results suggest that the rational fusion of NP and multiple M2e antigens is critical toward inducing protective immune responses, and the 4M2eNP fusion antigen may be employed to develop a universal influenza vaccine.

The immune response of rhesus macaques to novel vaccines comprising hepatitis B virus S, PreS1, and Core antigens

Therapeutic vaccines represent a unique approach to hepatitis B virus (HBV) treatment and have the potential to induce long-term control of infection. This study explored the immune responses of rhesus macaques to novel vaccines comprising the S, PreS1, and Core antigens of the HBV that showed promise as prophylactic and therapeutic approaches in a mouse model. The tested vaccines included two DNA vaccines (pVRC-SS1, pVRC-CS1), an HBV particle subunit (HBSS1) vaccine and the recombinant vaccinia virus- (RVJ-) based vaccines (RVJSS1 and RVJCS1) in which SS1 containing S (1-223 aa) and PreS1 (21-47 aa), CS1 containing Core (1-144 aa) and PreS1 (1-42 aa). The humoral immunity and cell-mediated immunity (CMI) induced by vaccines comprising the S, PreS1, and Core antigens of HBV were investigated in a longitudinal study that continued up to 98 weeks after the firstvaccination. In rhesus macaques, anti-PreS1 antibody was induced more rapidly than anti-S or anti-Core antibody after DNA vaccination. The antibody and cell-mediated immune responses against S, PreS1, and C were significantly enhanced in macaques boosted with RVJSS1 and RVJCS1, whereas the cell-mediated response to C was most robust and durable. The immune response to S, PreS1, and C was restored by HBSS1 boosting and detected in macaques until weeks 74 and 98 after the first vaccination. Additionally, robust neutralizing activity was detected at week 52. In conclusion, novel HBV vaccine candidates, especially those used for therapeutic applications should incorporate the PreS1 and Core antigens.

Recombinant vaccinia vector-based vaccine (Tiantan) boosting a novel HBV subunit vaccine induced more robust and lasting immunity in rhesus macaques

This study explored several prime-boost strategies in rhesus macaques using various novel hepatitis B virus (HBV) vaccines that showed promise as prophylactic and therapeutic approaches in our previous study using in a mouse model. The tested vaccines included an HBV particle subunit (HBSS1) vaccine and the recombinant vaccinia (RVJSS1) or adenoviral (rAdSS1) vector-based vaccines containing S (1-223aa) and PreS1 (21-47aa). The strength and maintenance of humoral activity (IgG and neutralizing antibodies) and cellular immunity (interferon-γ production assessed by IFN-γ enzyme-linked immunosorbent spot (ELISpot) assay) were investigated in a longitudinal study following various vaccination protocols until 79weeks post-vaccination. We found that HBSS1/RVJSS1 heterologous prime-boost elicits similar strong humoral immunity but more robust and lasting cellular immunity (CMI) than HBSS1/HBSS1 homologous vaccination in rhesus macaques. Furthermore, HBSS1/RVJSS1/RVJSS1 induced more robust and lasting CMI in macaques than did HBSS1/HBSS1/rAdSS1 vaccination. Therefore, HBSS1/RVJSS1/RVJSS1 is most promising candidates for protecting humans against HBV infection, especially for therapeutic application.

The amino acids 736-761 of the MERS-CoV spike protein induce neutralizing antibodies: implications for the development of vaccines and antiviral agents

Based on a bioinformatics analysis of the Middle East respiratory syndrome coronavvirus (MERS-CoV) S protein, we synthesized a panel of peptides coupled to keyhole limpet haemocyanin and used them to raise antibodies in rabbits. In addition, the recombinant receptor-binding domain (RBD) was used to raise polyclonal antibodies in mice. All of the antibodies raised by S-peptide immunisation were specific and sensitive for S protein expressed in transfected cells in the indirect immunofluorescence assay or Western blotting. The RBD efficiently elicited neutralizing antibodies against MERS-CoV by blocking viral entry at the binding step. Furthermore, we found that the SP3 peptide, corresponding to amino-acid residues 736-761 of the S protein, elicited robust neutralizing activities by blocking viral entry at the postbinding and membrane fusion steps. We conclude that amino-acid residues 736-761 of the S protein carry neutralizing epitopes that may be used in the development of vaccines and antiviral agents against MERS-CoV.

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.

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.

Human-leukocyte antigen class I Cw 1502 and class II DR 0301 genotypes are associated with resistance to severe acute respiratory syndrome (SARS) infection

One-hundred and thirty confirmed cases of severe acute respiratory syndrome (SARS) were recruited to evaluate their anti-SARS-coronavirus (CoV) antibody status and human leukocyte antigen (HLA) types in September 2006, 3 y after the SARS outbreaks in Taiwan. Western blot assay showed that 6.9% of participants still had anti-spike and anti-nucleocapside antibodies. A case-control study of the association of HLA with SARS revealed that the HLA-Cw1502 and DR0301 alleles conferred resistance against SARS infection (p<0.05).