Modified Vaccinia Virus Ankara Strain Research Articles

Creation of poxvirus expressing foot-and-mouth and peste des petits ruminant disease virus proteins

Foot-and-mouth disease (FMD) and Peste des petits ruminant disease (PPR) are acute and severe infectious diseases of sheep and are listed as animal diseases for compulsory immunization. However, there is no dual vaccine to prevent these two diseases. The Modified Vaccinia virus Ankara strain (MVA) has been widely used in the construction of recombinant live vector vaccine because of its large capacity of foreign gene, wide hostrange, high safety, and immunogenicity. In this study, MVA-GFP recombinant virus skeleton was used to construct dual live vector vaccines against FMD and PPR. The recombinant plasmid pUC57-FMDV P1-2A3CPPRV FH was synthesized and transfected into MVA-GFP infected CEF cells for homologous recombination. The results showed that a recombinant virus without fluorescent labeling was obtained after multiple rounds of plaque screening. The recombinant virus successfully expressed the target proteins, and the empty capsid of FMDV could be observed by transmission electron microscope (TME), and the expression levels of foreign proteins (VP1 and VP3) detected by ELISA were like those detected in FMDV-infected cells. This study laidthe foundation for the successful construction of a live vector vaccine against FMD and PPR. • A recombinant MVA expressing FMDVP12A3C and PRRV HF proteins • Both the FMDV and PRRV proteins inserted into the virus were expressed • The proteins expressed by the recombinant poxvirus were assembled into VLPs.

Heterologous boosting with recombinant VSV-846 in BCG-primed mice confers improved protection against Mycobacterium infection

ABSTRACT Tuberculosis (TB) remains a major health problem worldwide, and the development of effective vaccines is urgently needed. Vaccination strategies based on heterologous prime–boost protocols using Mycobacterium bovis bacillus Calmette-Guérin (BCG) as primer and modified vaccinia virus Ankara strain expressing the mycobacterial antigen Ag85A (MVA85A) as booster may increase the protective efficacy of BCG. In addition, vaccination with the recombinant viral vaccine vesicular stomatitis virus (VSV)-846 (Rv3615c, Mtb10.4, and Rv2660c) can elicit a remarkable T-cell-mediated immune response and provide an effective long-term protection after the BCG challenge. In this study, we used VSV-846 to boost BCG and evaluated its immunogenicity in BALB/c mice. In this prime–boost approach, boosting with VSV-846 significantly enhanced IFN-γ CD4 T cell responses, which are crucial for anti-TB immune responses. Moreover, VSV-846 boosting significantly reduced pathology compared with mock vaccination, and decreased the bacterial loads in lung tissues compared with BCG or VSV-846 vaccination alone. The analysis of vaccine-induced immunity identified that polyfunctional T cells might contribute to the enhanced protection by VSV-846 boosting. This study proved that viral booster VSV-846 in mice improved the protection against mycobacteria infection, which could be helpful in designing an efficient vaccination strategy against TB in humans.

Modified Vaccinia virus Ankara but not vaccinia virus induces chemokine expression in cells of the monocyte/macrophage lineage.

BackgroundThe orthopoxvirus strain Modified Vaccinia virus Ankara (MVA) rapidly induces innate immune responses. Previously, we demonstrated that CCL2 and CCR1 are important players in MVA induced recruitment of leukocytes to the lung. Alveolar macrophages are sentinel cells in the lung, which are likely amongst the first cells of the immune system to encounter and respond to virus during respiratory infection. Therefore we examined the potential of the murine alveolar macrophage MH-S cell line as a model to study chemokine expression during infection with MVA and vaccinia virus (VACV) strain Western Reserve (WR).FindingsMVA but not VACV infected MH-S cells increased the expression of the CXCR2 acting chemokine CXCL2. MH-S cells constitutively produced CCL2 and CCR1 acting chemokines CCL3, CCL5 and CCL9. Consequently, supernatants of mock treated and virus infected MH-S cells induced chemotaxis of murine promyelocyte MPRO cells and human monocytic THP-1 cells at the same level. However, supernatants of MVA infected MH-S cells significantly increased chemotaxis of the CCR2 deficient human monocytic cell line U-937. Chemotaxis of all three cell types was inhibited by J 113863, a CCR1 antagonist. Additionally, we show that MVA but not VACV WR infection of THP-1 cells induces expression of C-C motif and C-X-C motif chemokines and generates a chemotactic activity for monocytes, which was J 113863 sensitive.ConclusionsThese results extend our previous findings, demonstrating that MVA but not VACV WR induces chemokine production in alveolar macrophages and monocytes, which can induce recruitment of monocytes in a CCR1 dependent manner.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-015-0252-1) contains supplementary material, which is available to authorized users.

Immunogenicity and protective efficacy of heterologous prime-boost regimens with mycobacterial vaccines and recombinant adenovirus- and poxvirus-vectored vaccines against murine tuberculosis

To evaluate regimens using bacillus Calmette-Guérin (BCG) or recombinant BCG (rBCG) overexpressing Ag85B for priming, followed by boosting with a modified vaccinia virus Ankara strain (MVA) and/or adenovirus vector (AD) expressing an Ag85B-ESAT6 fusion protein. Cellular and humoral immune responses were determined after subcutaneous vaccination, which was employed to trigger systemic immunity against intravenous infection in a mouse model of tuberculosis (TB). Bacterial loads and lung histology were evaluated. The relative IgG2a and IgG1 antibody levels indicated that the viral-vectored vaccines generated a T-helper type 1 (Th1)-biased response after two doses of viral boost vaccinations. Boosting BCG-primed mice with viral vaccines induced a Th1 immune response that included both CD4 and CD8 T-cells generating antigen-specific interferon-gamma (IFN-γ) and CD8 T cytotoxic activity. Only mice vaccinated with two different viral boosters after BCG priming exhibited a significant reduction in bacterial burden in the lung after challenge. Histology examinations confirmed the attenuation of lung damage and more compact granulomas. After mycobacteria priming, boosting with AD85B-E6 followed by MVA85B-E6 afforded better protection than the reverse order of administration of the viral vectors. This study demonstrates the potential of multiple heterologous viral booster vaccines, although the exact correlates of protection and optimal regimens should be further investigated for the rational design of future vaccine strategies.

Viral Booster Vaccines Improve Mycobacterium bovis BCG-Induced Protection against Bovine Tuberculosis

Previous work with small-animal laboratory models of tuberculosis has shown that vaccination strategies based on heterologous prime-boost protocols using Mycobacterium bovis bacillus Calmette-Guérin (BCG) to prime and modified vaccinia virus Ankara strain (MVA85A) or recombinant attenuated adenoviruses (Ad85A) expressing the mycobacterial antigen Ag85A to boost may increase the protective efficacy of BCG. Here we report the first efficacy data on using these vaccines in cattle, a natural target species of tuberculous infection. Protection was determined by measuring development of disease as an end point after M. bovis challenge. Either Ad85A or MVA85A boosting resulted in protection superior to that given by BCG alone: boosting BCG with MVA85A or Ad85A induced significant reduction in pathology in four/eight parameters assessed, while BCG vaccination alone did so in only one parameter studied. Protection was particularly evident in the lungs of vaccinated animals (median lung scores for naïve and BCG-, BCG/MVA85A-, and BCG/Ad85A-vaccinated animals were 10.5, 5, 2.5, and 0, respectively). The bacterial loads in lymph node tissues were also reduced after viral boosting of BCG-vaccinated calves compared to those in BCG-only-vaccinated animals. Analysis of vaccine-induced immunity identified memory responses measured by cultured enzyme-linked immunospot assay as well as in vitro interleukin-17 production as predictors of vaccination success, as both responses, measured before challenge, correlated positively with the degree of protection. Therefore, this study provides evidence of improved protection against tuberculosis by viral booster vaccination in a natural target species and has prioritized potential correlates of vaccine efficacy for further evaluation. These findings also have implications for human tuberculosis vaccine development.

Extracellular vesicles containing virus-encoded membrane proteins are a byproduct of infection with modified vaccinia virus Ankara

Vaccinia virus is a structurally complex virus that multiplies in the cell cytoplasm. The assembly of Vaccinia virus particles and their egress from infected cells exploit cellular pathways. Most notably, intracellular mature viral particles are enwrapped by Golgi-derived or endosomal vesicles. These enveloped particles, enriched in virus-encoded proteins, migrate to the cell surface where they are released into the extracellular space through fusion of their outer envelope with the cell membrane. We report that baby hamster kidney cells productively infected with the modified vaccinia virus Ankara strain (MVA) also release extracellular vesicles containing virus-encoded envelope proteins but devoid of any virus cargo. Such vesicles were visualized on the cell surface by electron microscopy and immunogold labelling of the B5 envelope protein. A portion of the B5 protein was found to be associated with non-viral material in high speed ultracentrifugation pellets and displayed a buoyant density characteristic of exosomes released by some cell types. An unrelated transmembrane protein (CD40 ligand) encoded by the MVA genome was also incorporated into extracellular vesicles but not into the envelopes that surround extracellular enveloped virus. High speed pellets obtained by centrifugation of culture medium from cells infected with MVA encoding CD40 ligand displayed the ability to induce dendritic cell maturation suggesting that the ligand is on the outer surface of the extracellular vesicles. We propose that the formation of extracellular vesicles after vaccinia virus infection is a byproduct of the pathway leading to the formation of extracellular enveloped virus.

Evaluation of the recognition of Theileria parva vaccine candidate antigens by cytotoxic T lymphocytes from Zebu cattle

East Coast fever (ECF) is a highly fatal lymphoproliferative disease of cattle caused by Theileria parva, a tick-borne intracellular apicomplexan parasite. Parasite antigens that are targets of protective cytotoxic T lymphocyte (CTL) responses are required to formulate a sub-unit vaccine against ECF. A number of CTL target antigens have recently been identified and initial evaluation has shown their vaccine potential. This study aimed to evaluate whether these antigens were recognised by CTL obtained from six genetically diverse Zebu cattle immunized with a cocktail of T. parva stocks. T. parva Muguga specific polyclonal CD8 + CTL lines were generated and confirmed to specifically lyse autologous infected cells. CTL recognition of autologous skin fibroblasts (iSF) transduced with recombinant modified vaccinia virus Ankara strain (MVA) expressing previously identified T. parva Muguga vaccine candidate antigens was evaluated using an IFN-γ ELISpot assay. CTL lines from one of the four calves, BY120, responded specifically to cells infected with MVA expressing the antigen Tp2 and synthetic peptides were employed to map a new CTL epitope on this antigen. Immunoscreening of the T. parva genome with these CTL lines should identify novel antigens that will constitute valuable additions to the vaccine candidates currently being evaluated.

High level protein expression in mammalian cells using a safe viral vector: Modified vaccinia virus Ankara

Vaccinia virus vectors are attractive tools to direct high level protein synthesis in mammalian cells. In one of the most efficient strategies developed so far, the gene to be expressed is positioned downstream of a bacteriophage T7 promoter within the vaccinia genome and transcribed by the T7 RNA polymerase, also encoded by the vaccinia virus genome. Tight regulation of transcription and efficient translation are ensured by control elements of the Escherichia coli lactose operon and the encephalomyocarditis virus leader sequence, respectively. We have integrated such a stringently controlled expression system, previously used successfully in a standard vaccinia virus backbone, into the modified vaccinia virus Ankara strain (MVA). In this manner, proteins of interest can be produced in mammalian cells under standard laboratory conditions because of the inherent safety of the MVA strain. Using this system for expression of β-galactosidase, about 15 mg protein could be produced from 10 8 BHK21 cells over a 24-h period, a value 4-fold higher than the amount produced from an identical expression system based on a standard vaccinia virus strain. In another application, we employed the MVA vector to produce human tubulin tyrosine ligase and demonstrate that this protein becomes a major cellular protein upon induction conditions and displays its characteristic enzymatic activity. The MVA vector should prove useful for many other applications in which mammalian cells are required for protein production.

Identification of Vaccinia CD8 + T-Cell Epitopes Conserved among Vaccinia and Variola Viruses Restricted by Common MHC Class I Molecules, HLA-A2 or HLA-B7

Immunization with vaccinia virus results in long-lasting protection against smallpox and is an approach that has been successfully used to eliminate natural smallpox infections worldwide. Today, vaccinia virus is very important not only as a vaccine virus to protect human against smallpox, but also as an expression vector for immunization against other infectious diseases, such as HIV and cancer. In this article, we identify three new vaccinia human CD8 + T-cell epitopes conserved among vaccinia and variola viruses restricted by HLA-A2, HLA-B7, or HLA-B*3502, which belongs to the HLA-B7 supertype. Identification of these CD8 + T-cell epitopes restricted by common HLA alleles will help to quantitate human CD8 + T-cell responses to licensed and experimental smallpox vaccines and to vaccinia virus vectors. CD8 + T-cell responses specific to these epitopes can also be used to quantitate cellular immune responses, especially with new smallpox vaccines that do not induce a “take,” such as the modified vaccinia virus Ankara strain. Combined with previous reports by us and others, these results show that there are some vaccinia viral proteins containing multiple epitopes restricted by different MHC molecules of humans and mice.

Modified vaccinia virus Ankara multiplies in rat IEC-6 cells and limited production of mature virions occurs in other mammalian cell lines

Recombinant viruses based on modified vaccinia virus Ankara (MVA) are vaccine candidates against infectious diseases and cancers. Presently, multiplication of MVA has been demonstrated in chicken embryo fibroblast and baby hamster kidney (BHK-21) cells only. The multiplication and morphogenesis of a recombinant (MVA-HANP) and non-recombinant MVA strain in BHK-21 and 12 other mammalian cell lines have now been compared. Rat IEC-6 cells were fully permissive to MVA infection. The virus yield in IEC-6 cells was similar to that obtained in BHK-21 cells at low as well as high multiplicities of infection. Vero cells were semi-permissive to MVA infection. Mature virions were produced in supposedly non-permissive cell lines. The multiplication and morphogenesis of non-recombinant MVA and MVA-HANP were similar. These results are relevant to the production and biosafety of MVA-vectored vaccines.

Safety and immunogenicity of IMVAMUNE, a promising candidate as a third generation smallpox vaccine

A Phase I trial was performed to investigate the safety and immunogenicity of the third generation smallpox vaccine MVA-BN ® (IMVAMUNE™), a highly attenuated clone derived from the Modified Vaccinia Virus Ankara strain 571, in naive and pre-immunized subjects. A total of 86 healthy subjects received the vaccine in five groups using different doses and routes of administration. All 38 subjects seroconverted in the groups receiving the highest dose (10 8 TCID 50). All vaccinations were well tolerated with mainly mild or moderate pain at the injection site being the most frequent symptom. The results indicate that MVA-BN ® has the potential to be developed as an efficient and safe alternative to the conventional smallpox vaccines such as Lister-Elstree or Dryvax ®. Unique attributes render it a promising candidate for prophylactic mass immunization, even in subjects for whom conventional smallpox vaccines are contraindicated.

Identification of Murine Poxvirus-Specific CD8+ CTL Epitopes with Distinct Functional Profiles

Murine T cell epitopes against vaccinia virus (VV) have not been characterized to date in part due to the large and complex genome of VV. We have identified and characterized two CD8+ T cell epitopes on the A47L (modified VV Ankara strain (MVA)-029) and J6R (MVA-043) proteins of VV that are Db and Kb restricted, respectively. Following i.p. immunization with VV New York City Board of Health (NYCBH) strain, MVA-029 peptide-stimulated splenocytes secreted IFN-gamma from 7 days to 7 mo postimmunization, and virus-stimulated effectors were also able to lyse MVA-029-pulsed target cells at the same time points. In contrast, MVA-043 peptide-stimulated splenocytes secreted very low levels of IFN-gamma only at day 7 but maintained the ability to lyse target cells up to 2 mo postimmunization. Both MVA-029 and MVA-043 peptide-stimulated lymph node cells degranulated similarly as assessed by Ag-induced CD107 expression. T cell responses to whole-virus stimulation remained robust and steady during the acute and memory T cell response to VV. Identification of T cell epitopes on VV will enable further studies to increase our understanding of the role of CD8+ T cells in VV infection and assist in the design of new protective strategies.

T‐cell‐mediated protective efficacy of a systemic vaccine approach in cynomolgus monkeys after SIV mucosal challenge

The immunogenicity and the protective efficacy of a new polyvalent triple vector (DNA/SFV/MVA) based vaccine against mucosal challenge with pathogenic SIVmac251 were investigated. Cynomolgus monkeys (Macaca fascicularis) were primed intradermally with DNA, boosted twice subcutaneously with recombinant Semliki Forest virus (rSFV) and finally intramuscularly with recombinant Modified Vaccinia Virus Ankara strain (rMVA). Both DNA and recombinant viral vectors expressed SIV proteins (Gag, Pol, Tat, Rev, Nef and Env). The vaccinated monkeys developed T helper proliferative responses to viral antigens after the second immunization while interferon (IFN)-gamma enzyme-linked immunosorbent spot-forming cell assay (ELISPOT) specific responses appeared only after the last boost with rMVA. Upon intrarectal challenge with pathogenic SIVmac251, three of four vaccinated monkeys were either fully protected or exhibited a dramatic reduction of virus replication up to undetectable level. A major contribution to this protective effect appeared to be the anamnestic T-cell IFN-gamma ELISPOT responses to vaccine antigens (Gag, Rev, Tat, Nef) that mirrored the viral clearance. These results underline the efficacy of a multiprotein approach in combination with a triple vector system of antigen delivery.

Protective efficacy of a multicomponent vector vaccine in cynomolgus monkeys after intrarectal simian immunodeficiency virus challenge.

We investigated the protective efficacy of a systemic triple vector (DNA/rSFV/rMVA)-based vaccine against mucosal challenge with pathogenic simian immunodeficiency virus (SIV) in cynomolgus monkeys. Animals were immunized at week 0 with DNA (intradermally), at weeks 8 and 16 with recombinant Semliki Forest virus (rSFV, subcutaneously) and finally, at week 24, with recombinant modified vaccinia virus Ankara strain (rMVA, intramuscularly). Both DNA and recombinant viral vectors expressed a wide range of SIV proteins (Gag, Pol, Tat, Rev, Env and Nef). This immunization strategy elicited cell-mediated rather than humoral responses that were especially increased following the last boost. Upon intrarectal challenge with pathogenic SIVmac251, three of the four vaccinated monkeys dramatically abrogated virus load to undetectable levels up to 41 weeks after challenge. A major contribution to this vaccine effect appeared to be the T-cell-mediated immune response to vaccine antigens (Gag, Rev, Tat, Nef) seen in the early phase of infection in three of the four vaccinated monkeys. Indeed, the frequency of T-cells producing antigen-induced IFN-gamma mirrored virus clearance in the vaccinated and protected monkeys. These results, reminiscent of the efficacy of live attenuated virus vaccines, suggest that vaccination with a combination of many viral antigens can induce a robust and stable vaccine-induced immunity able to abrogate virus replication.

A new boost for malaria vaccines.

<h2>Abstract</h2> <i>Plasmodium falciparum</i> kills 1–3 million people each year, most of them are children in sub-Saharan Africa. Immunization with a specific sequence of different vaccine carriers (prime boost) is particularly effective in conferring sterile protective immunity against the pre-erythrocytic stage in animal models of malaria. Here, we review the immunogenicity and protective efficacy data from the first human trial of a prime–boost vaccine against pre-erythrocytic malaria. This vaccine is based on priming with DNA and boosting with modified vaccinia virus Ankara strain. The limitations and future challenges facing this and other vaccines against human malaria are discussed.

Heterologous priming-boosting immunization of cattle with Mycobacterium tuberculosis 85A induces antigen-specific T-cell responses.

Heterologous priming-boosting vaccination regimens involving priming with plasmid DNA antigen constructs and inoculating (boosting) with the same recombinant antigen expressed in replication-attenuated poxviruses have recently been demonstrated to induce immunity, based on CD4(+)- and CD8(+)-T-cell responses, against several diseases in both rodents and primates. We show that similar priming-boosting vaccination strategies using the 85A antigen of Mycobacterium tuberculosis are effective in inducing antigen-specific gamma interferon-secreting CD4(+) and CD8(+) T cells, detected by a bovine enzyme-linked immunospot assay, in Bos indicus cattle. T-cell responses induced by priming with either plasmid DNA or fowlpox virus 85A constructs were enhanced by boosting with modified vaccinia virus Ankara expressing the same antigen administered intradermally. On the basis of the data, it appears that intradermal priming was more effective than intramuscular delivery of the priming dose for boosting with the modified vaccinia virus Ankara strain in cattle. Using either fowlpox virus or DNA priming, there was a significant bias toward induction of CD4(+)- rather than CD8(+)-T-cell responses. These data illustrate the general applicability of priming-boosting vaccination strategies for induction of antigen-specific T-cell responses and suggest that the method may be useful for development of veterinary vaccines.

Presentation of a new H-2D(k)-restricted epitope in the Tax protein of human T-lymphotropic virus type I is enhanced by the proteasome inhibitor lactacystin.

Tax, the trans-activator of human T-lymphotropic virus type I (HTLV-I), is the dominant target antigen for cytotoxic T lymphocytes (CTLs) in the majority of infected individuals, although the reason for this immunodominance is not clear. Tax has been shown to associate physically with the proteasome, a protease that is responsible for the generation of the majority of major histocompatibility complex (MHC) class I ligands recognized by CTLs. This association could lead to the preferential targeting of Tax to the MHC class I pathway and account for its high immunogenicity. Here, the CTL response to Tax was investigated in mice by priming with a Tax expression vector and boosting with a Tax recombinant vaccinia virus (modified vaccinia virus Ankara strain). This approach led to the identification of a new H-2D(k)-restricted epitope in Tax, amino acid residues 38-46, sequence ARLHRHALL. Surprisingly, presentation of this epitope was found to be enhanced by the proteasome inhibitor lactacystin, although Tax was shown to associate with proteasomes in murine cells. The difficulties encountered in generating Tax-specific CTL responses and the results of enzyme-linked immunospot (ELISpot) analysis suggested that Tax is only poorly immunogenic for CTLs in mice. Therefore, the immunodominance of Tax in human CTL responses to HTLV-I is probably not due to an intrinsic property of the protein itself, such as an association with the proteasome, but instead may result from the fact that Tax is the predominant protein synthesized early after infection.

Protective immunity against Mycobacterium tuberculosis induced by dendritic cells pulsed with both CD8(+)- and CD4(+)-T-cell epitopes from antigen 85A.

Immunization with DNA followed by modified vaccinia virus Ankara strain, both expressing the antigen 85A, induced both CD4(+)- and CD8(+)-T-cell responses in BALB/c mice. Following challenge with Mycobacterium tuberculosis, this prime-boost regimen produced protection equivalent to that conferred by Mycobacterium bovis BCG. Following immunization with dendritic cells pulsed with an antigen 85A CD4(+)- or CD8(+)-restricted epitope, alone or in combination, copresentation of both epitopes on the same dendritic cell was required for protection, demonstrating that induced CD8(+) T cells can play a protective role against tuberculosis.

Enhanced CD8 + T cell immune response against a V3 loop multi-epitope polypeptide (TAB13) of HIV-1 Env after priming with purified fusion protein and booster with modified vaccinia virus Ankara (MVA-TAB) recombinant: a comparison of humoral and cellular immune responses with the vaccinia virus Western Reserve (WR) vector

The humoral and cytotoxic T-lymphocyte (CTL) responses have been shown to be determinant in the clearance of many viral infections and because of those characteristics, vaccine candidates against AIDS are designed to enhance both arms of the immune system. While a protocol of immunization able to confer protection in humans against HIV will have to await the results of current clinical trials, it remains important to identify protocols of immunization in animals that achieve significant levels of humoral and cellular immune responses to HIV. In this study we have carried out a comparative analysis of the immune responses elicited in mice immunized with recombinants based on the modified vaccinia virus Ankara strain (rMVA) versus the Western Reserve strain (WR) of vaccinia virus (rVV), both expressing a V3 loop multi-epitopic protein from eight different HIV isolates (TAB13). We found that during priming, rMVA elicited a two- to three-fold higher specific CD8 + T cell response than rVV. Similar enhancement was observed during priming with purified protein TAB13 followed by a booster with rMVA. The epitopes LR150, MN and IIIB, located at the ends and in the middle of the chimeric protein, were able to induce a specific CD8 + T cell response, both after priming or prime/booster with the recombinant viruses but not after prime/booster with TAB13. By examining the cytokine pattern, the immune response triggered by these vectors was of Th-1 type. Humoral immune responses were higher in animals immunized with TAB13/TAB13 or TAB13/rVV than in animals immunized with TAB13/rMVA. These findings demonstrate that during priming or in a prime/booster immunizations, rMVA is superior to rVV in the ability to enhance specific cellular responses to an HIV-1 protein, and that both humoral and cellular immune responses to theV3 loop epitope of HIV-1 Env can be obtained by priming with TAB13 followed by a booster with viral vectors.

Cowpox Virus and Other Members of the Orthopoxvirus Genus Interfere with the Regulation of NF-κB Activation

NF-kappaB comprises a family of transcription factors that regulate key immune processes. In this study, the effects of orthopoxvirus infection upon the activation of NF-kappaB were examined. During the early phase of infection, cowpox virus can inhibit the induction of NF-kappaB-regulated gene expression by interfering with the process of IkappaBalpha degradation. Although either okadaic acid or tumor necrosis factor (TNF) treatment of infected cells can induce IkappaBalpha phosphorylation, further processing of IkappaBalpha is inhibited. These results suggest that cowpox virus is capable of inhibiting the activation of NF-kappaB at a point where multiple signal transduction pathways converge. Other orthopoxviruses affect NF-kappaB activity, but in a type-specific manner. Raccoonpox virus and vaccinia virus (Copenhagen strain) negatively affect NF-kappaB induction by TNF. In contrast, the modified vaccinia virus Ankara strain induces NF-kappaB activation, even in the absence of other stimuli. These findings suggest that orthopoxviruses may affect a broad range of virus-host interactions through their effects upon NF-kappaB activation. Moreover, because of the central role for NF-kappaB in immune processes and disease, these type-specific effects may contribute significantly to the immunogenic and pathogenic properties of poxviruses.