RESUMO
Vaccinia virus (VACV) is a notorious virus for a number of scientific reasons; however, most of its notoriety comes from the fact that it was used as a vaccine against smallpox, being ultimately responsible for the eradication of that disease. Nonetheless, many different vaccinia virus strains have been obtained over the years; some are suitable to be used as vaccines, whereas others are virulent and unsuitable for this purpose. Interestingly, different vaccinia virus strains elicit different immune responses in vivo, and this is a direct result of the genomic differences among strains. In order to evaluate the net result of virus-encoded immune evasion strategies of vaccinia viruses, we compared antiviral immune responses in mice intranasally infected by the highly attenuated and nonreplicative MVA strain, the attenuated and replicative Lister strain, or the virulent WR strain. Overall, cell responses elicited upon WR infections are downmodulated compared to those elicited by MVA and Lister infections, especially in determined cell compartments such as macrophages/monocytes and CD4+ T cells. CD4+ T cells are not only diminished in WR-infected mice but also less activated, as evaluated by the expression of costimulatory molecules such as CD25, CD212, and CD28 and by the production of cytokines, including tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), interleukin-4 (IL-4), and IL-10. On the other hand, MVA infections are able to induce strong T-cell responses in mice, whereas Lister infections consistently induced responses that were intermediary between those induced by WR and MVA. Together, our results support a model in which the virulence of a VACV strain is proportional to its potential to downmodulate the host's immune responses.IMPORTANCE Vaccinia virus was used as vaccine against smallpox and was instrumental in the successful eradication of that disease. Although smallpox vaccination is no longer in place in the overall population, the use of vaccinia virus in the development of viral vector-based vaccines has become popular. Nonetheless, different vaccinia virus strains are known and induce different immune responses. To look into this, we compared immune responses triggered by mouse infections with the nonreplicative MVA strain, the attenuated Lister strain, or the virulent WR strain. We observed that the WR strain was capable of downmodulating mouse cell responses, whereas the highly attenuated MVA strain induced high levels of cell-mediated immunity. Infections by the intermediately attenuated Lister strain induced cell responses that were intermediary between those induced by WR and MVA. We propose that the virulence of a vaccinia virus strain is directly proportional to its ability to downmodulate specific compartments of antiviral cell responses.
Assuntos
Imunidade Celular/imunologia , Vaccinia virus/imunologia , Vacínia/imunologia , Virulência/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/virologia , Galinhas/imunologia , Galinhas/virologia , Chlorocebus aethiops/imunologia , Chlorocebus aethiops/virologia , Citocinas/imunologia , Vetores Genéticos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Varíola/imunologia , Vacinação/métodos , Vacínia/virologia , Vacinas Virais/imunologiaRESUMO
HCV (hepatitis C virus) is a worldwide health problem nowadays. No preventive vaccine is available against this pathogen, and therapeutic treatments currently in use have important drawbacks, including limited efficacy. In the present work a recombinant fowlpox virus, FPCoE1, expressing a truncated HCV core-E1 polyprotein, was generated. FPCoE1 virus generally failed to elicit a humoral immune response against HCV antigens in BALB/c mice. By contrast, mice inoculated with FPCoE1 elicited a positive interferon-gamma secretion response against HCV core in ex-vivo ELISPOT (enzyme-linked immunospot) assays. Remarkably, mice inoculated with FPCoE1 significantly controlled viraemia in a surrogate challenge model with vvRE, a recombinant vaccinia virus expressing HCV structural antigens. In fact, 40% of the mice had no detectable levels of vvRE in their ovaries. Administration of FPCoE1 in vervet monkeys [Chlorocebus (formerly Cercophitecus) aethiops sabaeus] induced lymphoproliferative response against HCV core and E1 proteins in 50% of immunized animals. Monkeys immunized with FPCoE1 had no detectable levels of vvRE in their blood, whereas monkeys inoculated with FP9, the negative control virus, had detectable levels of vvRE in blood up to 7 days after challenge. In conclusion, recombinant fowlpox virus FPCoE1 is able to induce an anti-HCV immune response in mice and monkeys. This ability could be rationally employed to develop effective strategies against HCV infection by using FPCoE1 in combination with other vaccine candidates or antiviral treatments.
Assuntos
Chlorocebus aethiops/imunologia , Vírus da Varíola das Aves Domésticas/genética , Hepatite C/imunologia , Imunização , Polimorfismo de Nucleotídeo Único/imunologia , Vaccinia virus/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Chlorocebus aethiops/virologia , DNA Viral/genética , Ensaio de Imunoadsorção Enzimática , Feminino , Vírus da Varíola das Aves Domésticas/imunologia , Hepatite C/prevenção & controle , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único/genética , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas do Envelope Viral/administração & dosagem , Proteínas do Envelope Viral/genéticaRESUMO
A common meningococcal antigen designated P64k has been identified, cloned and expressed in Escherichia coli. The recombinant antigen is highly immunogenic in several animal species and its immunogenicity in healthy human volunteers is under investigation. Recently, P64k has been used as an immunological carrier for weak immunogens. To characterize the B-cell epitopes on P64k, recognized by immune sera obtained from mice, rabbits and monkeys, multiple overlapping peptides were synthesized and screened for antibody binding. Peptides covering the complete sequence of the P64k protein, 59 in all, of 20 amino acids each (overlapped by 10 residues), were synthesized. A number of continuous epitopes were detected with all sera, when immune and pre-immune bleeds were compared. For mouse and monkey sera, a few major antigenic peptides were identified, while the recognition of the rabbit serum was much more heterogeneous. Despite variation in the exact location of continuous epitopes defined by different anti-P64k sera, we found an immunogenic core region within the molecule, composed of amino acids Asp(524)-Gly(533). Consistently, in this protein segment there was an amino acid stretch located in a beta-hairpin loop, which is exposed to the solvent in the previously determined three-dimensional structure of the protein. This region is protruding and accessible to a sphere with a radius of 9 A.
Assuntos
Linfócitos B/imunologia , Mapeamento de Epitopos/métodos , Neisseria meningitidis/imunologia , Fosfoproteínas/imunologia , Sequência de Aminoácidos , Animais , Chlorocebus aethiops/imunologia , Feminino , Glicoproteínas de Membrana , Camundongos , Camundongos Endogâmicos BALB C , Proteínas dos Microfilamentos , Dados de Sequência Molecular , Fragmentos de Peptídeos/imunologia , Fosfoproteínas/química , Conformação Proteica , CoelhosRESUMO
Major histocompatibility complex expression of activated peripheral blood lymphocytes of captive African green monkeys from Barbados and from Africa were analyzed biochemically; class I molecules by one-dimensional isoelectric focusing and class II DR molecules by one-dimensional nonequilibrium pH gradient electrophoresis. Much less diversity was observed in the major histocompatability molecule expression of the African green monkeys of Barbados than in the African cohort.
Assuntos
Chlorocebus aethiops/imunologia , Antígenos de Histocompatibilidade Classe II/biossíntese , Antígenos de Histocompatibilidade Classe I/biossíntese , Complexo Principal de Histocompatibilidade , África , Animais , Barbados , Expressão Gênica , Variação Genética , Geografia , Antígenos HLA-DR/análise , Antígenos HLA-DR/biossíntese , Antígenos HLA-DR/isolamento & purificação , Antígenos de Histocompatibilidade Classe I/análise , Antígenos de Histocompatibilidade Classe I/isolamento & purificação , Antígenos de Histocompatibilidade Classe II/análise , Antígenos de Histocompatibilidade Classe II/isolamento & purificação , Focalização Isoelétrica , Ativação Linfocitária , Linfócitos/imunologiaRESUMO
It has been previously reported that guinea pigs inoculated with Tacaribe virus grown in suckling mouse brain, develop specific anti-Junín neutralizing antibodies (NA) after 45 days of infection and a typical secondary response after Junín virus challenge. Since in these experiments both viruses were grown in suckling mouse brain doubt was raised about the specificity of NA, considering the possibility that they were raised against host-cell antigens. In order to test this interpretation the following experiments were performed. Stocks of Tacaribe and Junín viruses were prepared in sucking mouse brain, in monkey kidney cells (Vero) and in rabbit kidney cells (RK13). Different groups of guinea-pigs were inoculated with 1000 TC ID50 from each stock of Tacaribe virus. The animals were challenged on day 66 p.i. with 1000 LD50 of Junín virus grown in suckling mouse brain. Animals were bled at 30, 60 and 80 days after Tacaribe virus infection and sera were assayed in neutralization tests against Tacaribe and Junín viruses grown in Vero or RK13 cells or suckling mouse brain. Specific NA against Junín virus were found in all sera on day 60 post Tacaribe infection, discarding the possibility that the antibodies were not specifically directed against virus antigens. However, it was observed that the antibody titers were higher when neutralization was performed using immune sera prepared with virus grown in the host used for virus antigen. These results suggest that during the process of budding, viruses recruit cellular antigens which enhance the immune response.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Arenaviridae/imunologia , Arenavirus do Novo Mundo/imunologia , Cultura de Vírus/métodos , Animais , Antígenos Virais/imunologia , Arenaviridae/crescimento & desenvolvimento , Arenavirus do Novo Mundo/crescimento & desenvolvimento , Encéfalo/imunologia , Linhagem Celular , Chlorocebus aethiops/imunologia , Reações Cruzadas , Rim/imunologia , Camundongos/imunologia , Testes de Neutralização , Coelhos/imunologia , Células Vero/imunologiaRESUMO
La inoculación de virus Tacaribe proveniente de cerebro de ratón lactante induce en el cobayo la aparición de anticurepos neutralizantes heterólogos anti-virus Junín. En este trabajo se trató de establecer si dichos anticuerpos neutralizantes estaban dirigidos contra antígenos celulares arrastados por los viriones al brotar o contra antígenos codificados por el genoma ciral. Con este fin de prepararon stocks de ambos virus en distintos huépedes (cerebro de ratón lactante, células Vero y RK13). Se inocularon cobayos con 1000 DICT50 de cada uno de los stocks de virus Tacaribe y 66 días más tarde se desafiaron con 1000 DL50 de virus Junín provenientes de cerebro de ratón. A los 30, 60 y 80 días p.i. con virus Tacaribe, se sangraron los animales y los inmunosueros obtenidos se ensayaron en reacciones directa y cruzada enfrentando a los virus Tacaribe y Junín crecidos en los distintos huésédes. Los resultados mostraron que en todos los casos los títulos de los sueros fueron mayores cuando se realizó la neutralización usando como antígeno virus que había multiplicado en el mismo huésped que el empleado para inmunizar a los animales. Sin embargo, el hecho que inmunosueros provenientes de animales inoculados con virus Tacaribe pudieran neutralizar al virus Junín cuando ambos virus provinieron de distintos huéspedes descarta la posibilidad que los anticurepos heterólogos encontrados en estos animales en el día 60 p.i. con Tacaribe estén dirigidos solamente contra antígenos celulares. Por el contrario dichos anticuerpos neutralizantes parecen estar dirigidos contra antígenos codificados por el genoma viral, confirmando las estreschas relaciones antigénicas existentes entre ambos virus
Assuntos
Arenaviridae/imunologia , Arenavirus do Novo Mundo/imunologia , Cultura de Vírus/métodos , Antígenos Virais/imunologia , Arenaviridae/crescimento & desenvolvimento , Arenavirus do Novo Mundo/crescimento & desenvolvimento , Linhagem Celular , Células Vero/imunologia , Chlorocebus aethiops/imunologia , Cérebro/imunologia , Reações Cruzadas , Rim/imunologia , Testes de Neutralização , Coelhos/imunologiaRESUMO
La inoculación de virus Tacaribe proveniente de cerebro de ratón lactante induce en el cobayo la aparición de anticurepos neutralizantes heterólogos anti-virus Junín. En este trabajo se trató de establecer si dichos anticuerpos neutralizantes estaban dirigidos contra antígenos celulares arrastados por los viriones al brotar o contra antígenos codificados por el genoma ciral. Con este fin de prepararon stocks de ambos virus en distintos huépedes (cerebro de ratón lactante, células Vero y RK13). Se inocularon cobayos con 1000 DICT50 de cada uno de los stocks de virus Tacaribe y 66 días más tarde se desafiaron con 1000 DL50 de virus Junín provenientes de cerebro de ratón. A los 30, 60 y 80 días p.i. con virus Tacaribe, se sangraron los animales y los inmunosueros obtenidos se ensayaron en reacciones directa y cruzada enfrentando a los virus Tacaribe y Junín crecidos en los distintos huésédes. Los resultados mostraron que en todos los casos los títulos de los sueros fueron mayores cuando se realizó la neutralización usando como antígeno virus que había multiplicado en el mismo huésped que el empleado para inmunizar a los animales. Sin embargo, el hecho que inmunosueros provenientes de animales inoculados con virus Tacaribe pudieran neutralizar al virus Junín cuando ambos virus provinieron de distintos huéspedes descarta la posibilidad que los anticurepos heterólogos encontrados en estos animales en el día 60 p.i. con Tacaribe estén dirigidos solamente contra antígenos celulares. Por el contrario dichos anticuerpos neutralizantes parecen estar dirigidos contra antígenos codificados por el genoma viral, confirmando las estreschas relaciones antigénicas existentes entre ambos virus (AU)