Recombinant RNA replicons derived from attenuated Venezuelan equine encephalitis virus protect guinea pigs and mice from Ebola hemorrhagic fever virus

RNA replicons derived from an attenuated strain of Venezuelan equine encephalitis virus (VEE), an alphavirus, were configured as candidate vaccines for Ebola hemorrhagic fever. The Ebola nucleoprotein (NP) or glycoprotein (GP) genes were introduced into the VEE RNA downstream from the VEE 26S promoter in place of the VEE structural protein genes. The resulting recombinant replicons, expressing the NP or GP genes, were packaged into VEE replicon particles (NP-VRP and GP-VRP, respectively) using a bipartite helper system that provided the VEE structural proteins in trans and prevented the regeneration of replication-competent VEE during packaging. The immunogenicity of NP-VRP and GP-VRP and their ability to protect against lethal Ebola infection were evaluated in BALB/c mice and in two strains of guinea pigs. The GP-VRP alone, or in combination with NP-VRP, protected both strains of guinea pigs and BALB/c mice, while immunization with NP-VRP alone protected BALB/c mice, but neither strain of guinea pig. Passive transfer of sera from VRP-immunized animals did not confer protection against lethal challenge. However, the complete protection achieved with active immunization with VRP, as well as the unique characteristics of the VEE replicon vector, warrant further testing of the safety and efficacy of NP-VRP and GP-VRP in primates as candidate vaccines against Ebola hemorrhagic fever.     

Complete protection of mice against a lethal dose challenge of western equine encephalitis virus after immunization with an adenovirus-vectored vaccine

Western equine encephalitis virus (WEEV) is an important pathogen for both humans and equines. The virus is also listed as a bioterrorism agent due to its ability for aerosol transmission with high mortality. No commercial vaccines or antiviral drugs are available for the prevention and treatment of WEEV infection in humans. In this paper, we constructed a recombinant WEEV vaccine, designated as Ad5-WEEV, using a replication defective, human adenovirus serotype 5 (HAd5) as a delivery vector. Ad5-WEEV contains the E3-E2-6K-E1 structural protein gene of the 71V-1658 strain of WEEV and the E1 and E2 proteins were synthesized in cells inoculated with Ad5-WEEV. After intramuscular immunization of mice with two doses of Ad5-WEEV, neutralizing antibodies against WEEV were generated and the mice were completely protected from a lethal dose challenge of 71V-1658. In addition, we showed that passive transfer of serum from the Ad5-WEEV-immunized mice could partially control WEEV infection. These results demonstrate that HAd5 vectors are promising for WEEV vaccine development.     

Antitumor efficacy of Venezuelan equine encephalitis virus replicon particles encoding mutated HPV16 E6 and E7 genes

An effective vaccine for treating human papillomavirus (HPV)-associated malignancies such as cervical cancer should elicit strong T cell-mediated immunity (CMI) against the E6 and/or E7 proteins necessary for the malignant state. We have developed Venezuelan equine encephalitis (VEE) virus replicon particle (VRP) vaccines encoding the HPV16 E6 and E7 genes and tested their immunogenicity and antitumor efficacy. The E6 and E7 genes were fused to create one open reading frame and mutated at four or at five amino acid positions to inactivate their oncogenic potential. VRP encoding mutant or wild type E6 and E7 proteins elicited comparable cytotoxic T lymphocyte (CTL) responses to an immunodominant E7(49-57) epitope and generated comparable antitumor responses in several HPV16 E6(+)E7(+) tumor challenge models: protection from either C3 or TC-1 tumor challenge was observed in 100% of VRP-vaccinated mice. Eradication of C3 tumors was observed in approximately 90% of mice following therapeutic VRP vaccination. Eradication of HLF16 tumors lacking the E7(49-57) epitope was observed in 90% of human leukocyte antigen (HLA)-A(*)0201 transgenic mice following therapeutic VRP vaccination. Finally, the predicted inactivation of E6 and E7 oncogenic potential was confirmed by demonstrating normal levels of both p53 and retinoblastoma proteins in human mammary epithelial cells (MEC) infected with VRP expressing mutant E6 and E7 genes. These promising results support the continued development of mutant E6 and E7 VRP as safe and effective candidates for clinical evaluation against HPV-associated disease.     

A recombinant virus vaccine that protects against both Chikungunya and Zika virus infections

Chikungunya virus (CHIKV) and Zika virus (ZIKV) have recently expanded their range in the world and caused serious and widespread outbreaks of near pandemic proportions. There are no licensed vaccines that protect against these co-circulating viruses that are transmitted by invasive mosquito vectors. We report here on the development of a single-dose, bivalent experimental vaccine for CHIKV and ZIKV. This vaccine is based on a chimeric vesicular stomatitis virus (VSV) that expresses the CHIKV envelope polyprotein (E3-E2-6K-E1) in place of the VSV glycoprotein (G) and also expresses the membrane-envelope (ME) glycoproteins of ZIKV. This vaccine induced neutralizing antibody responses to both CHIKV and ZIKV in wild-type mice and in interferon receptor-deficient A129 mice, animal models for CHIKV and ZIKV infection. A single vaccination of A129 mice with the vector protected these mice against infection with both CHIKV and ZIKV. Our single-dose vaccine could provide durable, low-cost protection against both CHIKV and ZIKV for people traveling to or living in areas where both viruses are circulating, which include most tropical regions in the world.     

Envelope protein E1 as vaccine target for western equine encephalitis virus

Western equine encephalitis virus (WEEV) is a mosquito-borne RNA virus which causes lethal infection in humans and equines. There are no commercial vaccines or anti-WEEV drugs available for humans. We used replication-defective, human adenovirus serotype-5 (HAd5) as a delivery vector for developing WEEV vaccine. Our previous study found delivery of both E1 and E2 envelope proteins of WEEV by HAd5 vector offers complete protection against lethal challenge of WEEV. In this paper, we constructed a HAd5-vectored E1 vaccine, Ad5-E1. Mice given single-dose vaccination of Ad5-E1 were completely protected against both homologous and heterologous WEEV strains. The protection was rapid, which was achieved as early as day 7 after vaccination. In addition, Ad5-E1 induced a strong WEEV-specific T cell response. Our data suggest E1 is a potential target for developing single-dose, fast-acting, HAd5-vectored vaccine for WEEV.     

Experimental non-transmissible marker vaccines for classical swine fever (CSF) by trans-complementation of E(rns) or E2 of CSFV

Three mutants with deletions in the E2 gene of the infectious DNA copy of the classical swine fever virus (CSFV) strain-C were constructed: one missing the B/C domain of CSFV-E2 between amino acids (aa) 693 and 746, one missing the A domain between aa 800 and 864, and one missing the complete E2 between aa 689 and 1062. All three CSFV-E2 deletion mutants were unable to generate viable virus, indicating that each of the antigenic domains of E2 is essential for viability of CSFV. To rescue the CSFV-E2 deletion mutants SK6 cell lines constitutively expressing glycoprotein E2 of CSFV were generated. The rescued viruses infected and replicated in SK6 cells as demonstrated by expression of viral proteins, but this primary infection did not result in reproduction of infectious virus. Thus, these E2 complemented viruses are considered non-transmissible. In previous experiments, we showed that simultaneous injection of E(rns) complemented virus (Flc23) via intradermal (ID), intramuscular (IM) or intranasal (IN) routes conferred protection to pigs against a lethal challenge with CSFV [J. Virol. 74 (2000) 2973]. Here, we evaluate different routes of application (ID, IM or IN) with E(rns) complemented virus Flc23 in order to find the best route for complemented CSFVs. Intradermal injection with Flc23 protected pigs against a lethal CSFV challenge, whereas intramuscular injection induced partial protection, and intranasal injection did not mediate a protective immune response in pigs at all. We used the intradermal route of vaccination to test the E2 complemented viruses. Vaccination of pigs via the intradermal route with the E2 complemented CSFVs also resulted in the induction of antibodies and in (partial) protection against CSFV challenge. Pigs vaccinated with E2 complemented virus Flc4 (deletion B/C domain) survived a lethal CSFV challenge, whereas partial protection was induced in pigs vaccinated with Flc47 (deletion E2) or Flc48 (deletion A domain) E2 complemented viruses. Serological data demonstrate that these E2 complemented mutant viruses are, in combination with well known diagnostic tests based on E2, potential marker vaccines for CSF.     

Preclinical development of peptide vaccination combined with oncolytic MG1-E6E7 for HPV-associated cancer

Human papilloma virus (HPV)-associated cancer is a significant global health burden and despite the presence of viral transforming antigens within neoplastic cells, therapeutic vaccinations are ineffective for advanced disease. HPV positive TC1 cells are susceptible to viral oncolysis by MG1-E6E7, a custom designed oncolytic Maraba virus. Epitope mapping of mice vaccinated with MG1-E6E7 enabled the rational design of synthetic long peptide (SLP) vaccines against HPV16 and HPV18 antigens. SLPs were able to induce specific CD8+ immune responses and the magnitude of these responses significantly increased when boosted by MG1-E6E7. Logically designed vaccination induced multi-functional CD8+ T cells and provided complete sterilising immunity of mice challenged with TC1 cells. In mice bearing large HPV-positive tumours, SLP vaccination combined with MG1-E6E7 was able to clear tumours in 60% of mice and these mice were completely protected against a long term aggressive re-challenge with the TC1 tumour model. Combining conventional SLPs with the multi-functional oncolytic MG1-E6E7 represents a promising approach against advanced HPV positive neoplasia.     

Multiagent vaccines vectored by Venezuelan equine encephalitis virus replicon elicits immune responses to Marburg virus and protection against anthrax and botulinum neurotoxin in mice

The development of multiagent vaccines offers the advantage of eliciting protection against multiple diseases with minimal inoculations over a shorter time span. We report here the results of using formulations of individual Venezuelan equine encephalitis (VEE) virus replicon-vectored vaccines against a bacterial disease, anthrax; a viral disease, Marburg fever; and against a toxin-mediated disease, botulism. The individual VEE replicon particles (VRP) expressed mature 83-kDa protective antigen (MAT-PA) from Bacillus anthracis, the glycoprotein (GP) from Marburg virus (MBGV), or the H(C) fragment from botulinum neurotoxin (BoNT H(C)). CBA/J mice inoculated with a mixture of VRP expressing BoNT H(C) serotype C (BoNT/C H(C)) and MAT-PA were 80% protected from a B. anthracis (Sterne strain) challenge and then 100% protected from a sequential BoNT/C challenge. Swiss mice inoculated with individual VRP or with mixtures of VRP vaccines expressing BoNT H(C) serotype A (BoNT/A H(C)), MAT-PA, and MBGV-GP produced antibody responses specific to the corresponding replicon-expressed protein. Combination of the different VRP vaccines did not diminish the antibody responses measured for Swiss mice inoculated with formulations of two or three VRP vaccines as compared to mice that received only one VRP vaccine. Swiss mice inoculated with VRP expressing BoNT/A H(C) alone or in combination with VRP expressing MAT-PA and MBGV GP, were completely protected from a BoNT/A challenge. These studies demonstrate the utility of combining individual VRP vaccines into multiagent formulations for eliciting protective immune responses to various types of diseases.     

Immunity of two novel hepatitis C virus polyepitope vaccines

Hepatitis C virus (HCV) infection remains a serious public health burden around the world. So far there is no effective vaccine against this virus. Neutralizing antibody (NAb) responses to the epitopes within HCV E1 and E2 proteins are related to the resolution of hepatitis C infection. E. coli heat-labile enterotoxin B subunit (LTB) has been described as potent immunity adjuvants. In this study, we constructed recombinant pET vectors: pET-R9-Bp (B cell polyepitopes) expressing 7 epitopes from HCV E1 and E2 proteins including R9 (E2_384-411aa)-Bp (E1_313-327aa-E2_396-424aa-E2_436-447aa-E2_523-540aa-E2_610-627aa-E2_631-648aa) and pET-LTB-R9-Bp expressing LTB adjuvant in combination with R9-Bp. Recombinant proteins R9-Bp and LTB-R9-Bp were expressed successfully in E. coli and purified by the Ni-NTA column. Both R9-Bp and LTB-R9-Bp in BALB/c mice induced robust humoral immune response in the context of intraperitoneal or intramuscular immunization but not oral immunization. Intraperitoneal administration of LTB-R9-Bp induced a higher antibody titer (peak titer: 1:341000) than that of R9-Bp (peak titer: 1:85000) after the second boost (P = 0.0036 or 0.0002). However, comparable antibody peak titers were elicited for both R9-Bp and LTB-R9-Bp in intramuscular immunization albeit with significant difference (P = 0.0032) a week after the second boost. In addition, both R9-Bp and LTB-R9-Bp induced the secretion of cytokines including IFN-γ and IL-4 at similar levels. anti-sera induced by both R9-Bp and LTB-R9-Bp recognized native HCV E1 and E2 proteins. Moreover, these HCV-specific antisera inhibited significantly the entry of HCV (P < 0.0001). Taken together, these findings showed that E. coli-based both R9-Bp and LTB-R9-Bp could become promising HCV vaccines.     

Enhanced immune responses to E2 protein and DNA formulated with ISA 61 VG administered as a DNA prime–protein boost regimen against bovine viral diarrhea virus

The aim of this study was to develop and test an optimal vaccination strategy against bovine viral diarrhea virus (BVDV) based on the E2 glycoprotein of the BJ1305 strain. To achieve higher E2-specific antibody titers and to broaden the cellular immune response, a plasmid encoding the E2 protein (pcDNA3.1-E2) was constructed and a purified recombinant E2 protein was generated. The E2 protein was emulsified in the adjuvant ISA 61 VG prior to administration. We immunized mice three times with pcDNA3.1-E2 or the recombinant E2 protein or primed twice with pcDNA3.1-E2 and boosted once with the E2 protein. To evaluate the protection against BVDV conferred by the vaccines, the mice were challenged with BVDV strain Oregon C24V after the third immunization. Although all immunized mice developed humoral and cellular immune responses, the E2-specific antibody titers in the DNA prime–protein boost group were significantly higher than those elicited by either the DNA or the protein vaccine. In addition, vaccination with the E2 DNA vaccine induced higher percentages of CD4⁺IFN-γ⁺ T cells and CD8⁺IFN-γ⁺ T cells among total CD3⁺ T cells than the other regimens. The predominant antibody subclass in the vaccinated mice was IgG1. Serum tumor necrosis factor alpha (TNF-α) levels in the DNA prime–protein boost group were significantly higher after the third immunization than in the other groups. Moreover, the mice treated with the DNA prime–protein boost vaccination regimen acquired protection against BVDV challenge, as shown by a significant reduction of viremia, only minor pathological changes, and a lower viral antigen burden than in the control and solo vaccinated mice. These results demonstrate the potential advantage of a DNA prime–protein boost vaccination approach over a solo vaccination for the prevention of BVDV. The ability of this vaccine strategy to control and eradicate BVD in herds warrants further investigation.     

Protection of chickens,with or without maternal antibodies,against IBDV infection by a recombinant IBDV-VP2 protein

The use of avian herpesviruses (Marek's disease virus, MDV) as vectors to express the capsid protein of infectious bursal disease virus (IBDV) was well established, and its protection against IBDV challenge has been evaluated previously. However, there is little data about rMDV1 expressing the VP2 protein of IBDV protecting SPF and commercial chickens against virulent IBDV (vIBDV) challenge. In this study, we constructed a stable rMDV1 expressing the VP2 protein of IBDV by inserting the coding sequence within the US10 gene of MDVl by homologous recombination and designated this as rMDVl-US10L, and evaluated effectiveness of the recombinant VP2 protein with SPF chickens and commercial chickens with maternal antibodies in vIBDV challenge. The results can be summarized as follows: (1) We constructed a rMDV1 expressing IBDV-VP2 under the control of the MDV1 glycoprotein B (gB) promoter [rMDV1-US10L]. (2) rMDV-VP2 protein was readily expressed and induced 53% protection against a vIBDV challenge in SPF chickens with 10³ PFU/chicken, whereas 10⁴ PFU induced 73% protection. (3) Vaccination of commercial chickens having maternal antibodies to rMDV1-VP2 induced 87% protection in vIBDV challenge, which was similar to results using the live vaccine, BJ87 IBDV strain, in commercial chickens. These results demonstrate that the VP2 antigen expressed in the MDV vector was an effective and stable vaccine in correlation with the vaccine efficacy against lethal IBDV challenge, and can provide a better protective effect that is likely to persist for the life of the chickens.     

Vaccinia recombinants expressing early bovine papilloma virus (BPV1) proteins: retardation of BPV1 tumour development

Papillomaviruses are aetiological agents of epithelial proliferative diseases in animals and in man. It was previously demonstrated that animals inoculated with live vaccinia recombinants expressing early proteins of polyoma virus resist challenge with polyoma-tumour cells, and this approach has been extended to the development of a vaccine against papillomavirus-transformed cells. Bovine papillomavirus type 1 (BPV1), a virus responsible for dermal lesions in cattle, is a prototype virus of the papillomavirus group. Independent vaccinia recombinant viruses expressing the early E1, E2, E5, E6 or E7 open reading frames of BPV1 were tested for their ability to direct the expression of the corresponding protein in cultured cells. Recombinants were then assessed for their ability to elicit anti-tumour immunity in Fischer rats seeded with BPV1-transformed syngeneic FR3T3 cells. Retardation of tumour growth was observed in animals vaccinated with recombinants expressing E5, E6 or E7.     

Alphavirus replicon particles expressing the two major envelope proteins of equine arteritis virus induce high level protection against challenge with virulent virus in vaccinated horses

Replicon particles derived from a vaccine strain of Venezuelan equine encephalitis (VEE) virus were used as vectors for expression in vivo of the major envelope proteins (G(L) and M) of equine arteritis virus (EAV), both individually and in heterodimer form (G(L)/M). The immunogenicity of the different replicons was evaluated in horses, as was their ability to protectively immunize horses against intranasal and intrauterine challenge with a virulent strain of EAV (EAV KY84). Horses immunized with replicons that express both the G(L) and M proteins in heterodimer form developed neutralizing antibodies to EAV, shed little or no virus, and developed only mild or inapparent signs of equine viral arteritis (EVA) after challenge with EAV KY84. In contrast, unvaccinated horses and those immunized with replicons expressing individual EAV envelope proteins (M or G(L)) shed virus for 6-10 days in their nasal secretions and developed severe signs of EVA after challenge. These data confirm that replicons that co-express the G(L) and M envelope proteins effectively, induce EAV neutralizing antibodies and protective immunity in horses.     

Venezuelan equine encephalitis virus vectors expressing HIV-1 proteins: vector design strategies for improved vaccine efficacy

A live virus vaccine vector has been constructed from a molecularly cloned attenuated strain of Venezuelan equine encephalitis virus (VEE). High levels of foreign protein expression are regulated by an additional copy of the 26 S viral subgenomic RNA promoter. The position of this additional promoter and foreign gene in the VEE genome was predicted to have a major influence on expression level of the heterologous protein. Two sites in the genome were tested to determine the optimal site for expression of the matrix/capsid (MA/CA) coding region of human immunodeficiency virus (HIV-1). One vector contained the additional promoter and the MA/CA genes immediately downstream of the VEE E1 gene at the 3' end of the genome. In the second vector, the additional promoter was introduced immediately upstream from the authentic 26 S subgenomic promoter. Significantly higher levels of MA/CA were expressed from the downstream vector compared to the upstream vector. However, the stability of expression for both vectors was similar following passage in baby hamster kidney cells (BHK) cells. In BALB/c mice, the two vectors elicited similar levels of cellular immune responses to MA/CA as determined by bulk cytotoxic T-lymphocyte assays and precursor frequency analysis, but the humoral response induced by the downstream vector was significantly stronger. At 11 months post boosting with the downstream vector, serum antibody levels against HIV MA/CA were undiminished, and MA/CA specific CTLp were detectable in all mice tested. These findings suggest that VEE vectors can be optimized to elicit strong, balanced and long-lived immune responses to foreign viral proteins.     

A Phase 1 clinical trial of a DNA vaccine for Venezuelan equine encephalitis delivered by intramuscular or intradermal electroporation

Venezuelan equine encephalitis virus (VEEV), a mosquito-borne alphavirus, causes periodic epizootics in equines and is a recognized biological defense threat for humans. There are currently no FDA-licensed vaccines against VEEV. We developed a candidate DNA vaccine expressing the E3-E2-6K-E1 genes of VEEV (pWRG/VEE) and performed a Phase 1 clinical study to assess the vaccine's safety, reactogenicity, tolerability, and immunogenicity when administered by intramuscular (IM) or intradermal (ID) electroporation (EP) using the Ichor Medical Systems TriGrid™ Delivery System. Subjects in IM-EP groups received 0.5 mg (N = 8) or 2.0 mg (N = 9) of pWRG/VEE or a saline placebo (N = 4) in a 1.0 ml injection. Subjects in ID-EP groups received 0.08 mg (N = 8) or 0.3 mg (N = 8) of DNA or a saline placebo (N = 4) in a 0.15 ml injection. Subjects were monitored for a total period of 360 days. No vaccine- or device-related serious adverse events were reported. Based on the results of a subject questionnaire, the IM- and ID-EP procedures were both considered to be generally acceptable for prophylactic vaccine administration, with the acute tolerability of ID EP delivery judged to be greater than that of IM-EP delivery. All subjects (100%) in the high and low dose IM-EP groups developed detectable VEEV-neutralizing antibodies after two or three administrations of pWRG/VEE, respectively. VEEV-neutralizing antibody responses were detected in seven of eight subjects (87.5%) in the high dose and five of eight subjects (62.5%) in the low dose ID-EP groups after three vaccine administrations. There was a correlation between the DNA dose and the magnitude of the resulting VEEV-neutralizing antibody responses for both IM and ID EP delivery. These results indicate that pWRG/VEE delivered by either IM- or ID-EP is safe, tolerable, and immunogenic in humans at the evaluated dose levels.Clinicaltrials.gov registry number NCT01984983.     

LEE-encoded regulator (Ler) mutants elicit serotype-specific protection, but not cross protection, against attaching and effacing E. coli strains

We previously showed that single dose orogastric immunization with an attenuated regulatory Lee-encoded regulator (ler) mutant of the rabbit enteropathogenic Escherichia coli (REPEC) strain E22 (O103:H2) protected rabbits from fatal infection with the highly virulent parent strain. In the current study we assessed the degree of homologous (serotype-specific) and heterologous (cross-serotype) protection induced by immunization with REPEC ler mutant strains of differing serotypes, or with a prototype strain RDEC-1 (O15:H-) which expresses a full array of ler up-regulated proteins. We constructed an additional ler mutant using RDEC-1 thus, permitting immunization with a ler mutant of either serotype, O15 or O103, followed by challenge with a virulent REPEC strain of the same or different serotypes. Consistent with our previous data, the current study demonstrated that rabbits immunized with a RDEC-1 ler mutant were protected from challenge with virulent RDEC-H19A (RDEC-1 transduced with Shiga toxin-producing phage H19A) of the same serotype. Rabbits immunized with RDEC-1 or E22 derivative ler mutants demonstrated significant increase in serum antibody titers to the respective whole bacterial cells expressing O antigen but not to the LEE-encoded proteins. However, immunization with the ler mutants of either E22 or RDEC-1 failed to protect rabbits from infections with virulent organisms belonging to different serotypes. In contrast, rabbits immunized with the prototype RDEC-1 were cross protected against challenge with the heterologous E22 strain as shown by normal weight gain, and the absence of clinical signs of disease or characteristic attaching and effacing (A/E) lesions. Immunization with RDEC-1 induced significantly elevated serum IgG titers to LEE-encoded proteins. We thus, demonstrated homologous protection induced by the REPEC ler mutants and heterologous protection by RDEC-1. The observed correlation between elevated immune responses to the LEE-encoded proteins and the protection against challenge with heterologous virulent REPEC strain suggests that serotype-non-specific cross protection requires the expression of, and induction of antibody to, LEE-encoded virulence factors.     

Immune responses to recombinants of the South African vaccine strain of lumpy skin disease virus generated by using thymidine kinase gene insertion

The South African vaccine strain of lumpy skin disease virus (type SA-Neethling) is currently being developed as a vector for recombinant vaccines of economically important livestock diseases throughout Africa. In this study, the feasibility of using the viral thymidine kinase gene as the site of insertion was investigated and recombinant viruses were evaluated in animal trials. Two separate recombinants were generated and selected for homogeneity expressing either the structural glycoprotein gene of bovine ephemeral fever virus (BEFV) or the two structural glycoprotein genes of Rift Valley fever virus (RVFV). Both recombinants incorporate the enhanced green fluorescent protein (EGFP) as a visual marker and the Escherichia coli guanine phosphoribosyl transferase (gpt) gene for dominant positive selection. The LSDV-RVFV recombinant construct (rLSDV-RVFV) protected mice against virulent RVFV challenge. In a small-scale BEFV-challenge cattle trial the rLSDV-BEFV construct failed to fully protect the cattle against virulent challenge, although both a humoral and cellular BEFV-specific immune response was elicited.     

Venezuelan equine encephalitis vaccine with rearranged genome resists reversion and protects non-human primates from viremia after aerosol challenge

Live-attenuated V4020 vaccine for Venezuelan equine encephalitis virus (VEEV) containing attenuating rearrangement of the virus structural genes was evaluated in a non-human primate model for immunogenicity and protective efficacy against aerosol challenge with wild-type VEEV. The genomic RNA of V4020 vaccine virus was encoded in the pMG4020 plasmid under control of the CMV promoter and contained the capsid gene downstream from the glycoprotein genes. It also included attenuating mutations from the VEE TC83 vaccine, with E2-120Arg substitution genetically engineered to prevent reversion mutations. The population of V4020 vaccine virus derived from pMG4020-transfected Vero cells was characterized by next generation sequencing (NGS) and indicated no detectable genetic reversions. Cynomolgus macaques were vaccinated with V4020 vaccine virus. After one or two vaccinations including by intramuscular route, high levels of virus-neutralizing antibodies were confirmed with no viremia or apparent adverse reactions to vaccinations. The protective effect of vaccination was evaluated using an aerosol challenge with VEEV. After challenge, macaques had no detectable viremia, demonstrating a protective effect of vaccination with live V4020 VEEV vaccine.     

Intramuscular injection of plasmid DNA encoding cottontail rabbit papillomavirus E1, E2, E6 and E7 induces T cell-mediated but not humoral immune responses in rabbits

To test the efficacy of genetic vaccination against papillomavirus infection, plasmid DNA encoding cottontail rabbit papillomavirus (CRPV) E1, E2, E6, E7 or without insert were intramuscularly injected into five groups of rabbits. Peripheral blood mononuclear cells (PBMCs) showed specific proliferation upon in vitro stimulation with E1, E2, E6 or E7 proteins in a majority of vaccinated rabbits but Western blot analysis did not detect antibodies specific for these viral proteins in rabbit serum. All rabbits grew papillomas after virus challenge and none of the rabbits showed systemic papilloma regression. These observations showed that intramuscular injection of plasmid DNA encoding CRPV E1, E2, E6 or E7 induced CD4+ T cell-mediated but not humoral immune responses, and did not result in the protection of rabbits from virus infection.