RESUMO
We have constructed recombinant baculoviruses and vaccinia viruses containing cloned DNA, encoding either the envelope protein alone or all of the structural proteins (core, membrane and envelope) of louping ill virus. Glycosylated viral envelope protein, presented both inside and on the surface of insect and mammalian cells, was expressed by all four recombinant viruses. Differences in antigenic presentation of the envelope protein were observed between the envelope protein and structural protein constructs as well as between the insect and mammalian cell expression systems. Despite the expression of epitopes known to elicit neutralizing and protective antibodies when present in authentic antigen, the recombinant envelope protein expressed by either vector failed to induce, in mice or rabbits, either neutralizing or protective antibodies against louping ill virus.
Assuntos
Anticorpos Antivirais/biossíntese , Baculoviridae/imunologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Vaccinia virus/imunologia , Proteínas do Envelope Viral/imunologia , Sequência de Aminoácidos , Animais , Baculoviridae/genética , Sequência de Bases , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/crescimento & desenvolvimento , Genes Virais , Vetores Genéticos , Soros Imunes/química , Imunização Passiva , Meningoencefalomielite Ovina/imunologia , Camundongos , Dados de Sequência Molecular , Mariposas/genética , Testes de Neutralização , Coelhos , Proteínas Recombinantes/imunologia , Infecções por Togaviridae/imunologia , Tunicamicina/farmacologia , Vaccinia virus/genética , Proteínas do Envelope Viral/biossínteseAssuntos
Anticorpos Antivirais/análise , Cervos/imunologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Meningoencefalomielite Ovina/imunologia , Viremia/veterinária , Animais , Vírus da Encefalite Transmitidos por Carrapatos/patogenicidade , Meningoencefalite/imunologia , Meningoencefalite/veterinária , Ovinos , Viremia/imunologiaAssuntos
Tolerância Imunológica , Meningoencefalomielite Ovina/imunologia , Doenças dos Ovinos/imunologia , Toxoplasmose Animal/imunologia , Animais , Anticorpos Antivirais/análise , Complemento C3/análise , Vírus da Encefalite Transmitidos por Carrapatos/isolamento & purificação , Meningoencefalomielite Ovina/patologia , Camundongos , OvinosRESUMO
The response of six calves to subcutaneous inoculation with louping-ill virus was studied. All developed viraemia of low intensity which lasted two to four days followed by the appearance of haemagglutination inhibiting serum antibody. IgM was the predominant class of antibody until day 14. Only one calf developed clinical signs; following a brief period of incoordination on day 7 it became recumbent and was killed on day 12. Severe meningoencephalitis was detected in this calf and mild changes were observed in one of the five survivors which were killed on day 14 or 20. These findings are discussed in relation to the epidemiology of louping-ill and the diagnosis of the disease in cattle.
Assuntos
Doenças dos Bovinos/diagnóstico , Meningoencefalomielite Ovina/diagnóstico , Animais , Anticorpos Antivirais/análise , Bovinos , Doenças dos Bovinos/imunologia , Doenças do Sistema Nervoso Central/diagnóstico , Doenças do Sistema Nervoso Central/veterinária , Meningoencefalomielite Ovina/imunologia , Masculino , OvinosRESUMO
Mice were infected with an avirulent cyst-producing strain of Toxoplasma gondii and given injections of louping-ill virus 7 days later; control mice were given virus but not Toxoplasma. Test and control mice were then killed, in groups, 2, 4, 6, 8 and 10 days later. In the dually infected mice viraemia was later, greater and more prolonged; titres of virus recovered from brain and spleen were greater; production and haemagglutinating antibody to louping-ill virus was later and less, and inflammation in the brain was more severe, than in mice given virus alone. We suggest that T. gondii suppressed the immunity of mice, making them more susceptible to the virus, and that a significant proportion of the increased number of inflammatory cells observed in the brain could have been toxoplasma specific and not virus-specific and hence contributed to the increased susceptibility of the dually infected mice to louping-ill virus.
Assuntos
Tolerância Imunológica , Meningoencefalomielite Ovina/imunologia , Toxoplasmose Animal/imunologia , Animais , Anticorpos Antivirais/biossíntese , Encéfalo/microbiologia , Encefalite/complicações , Vírus da Encefalite Transmitidos por Carrapatos/crescimento & desenvolvimento , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Testes de Inibição da Hemaglutinação , Meningoencefalomielite Ovina/complicações , Meningoencefalomielite Ovina/microbiologia , Camundongos , Ovinos , Baço/microbiologiaAssuntos
Tolerância Imunológica , Meningoencefalomielite Ovina/imunologia , Camundongos , Doenças dos Roedores/imunologia , Toxoplasmose Animal/imunologia , Animais , Anticorpos Antivirais/análise , Encéfalo/patologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Meningoencefalomielite Ovina/complicações , Meningoencefalomielite Ovina/patologia , Doenças dos Roedores/patologia , Ovinos , Toxoplasmose Animal/complicações , Toxoplasmose Animal/patologia , Viremia/veterináriaAssuntos
Doenças dos Cavalos/etiologia , Meningoencefalomielite Ovina/etiologia , Animais , Anticorpos Antivirais/análise , Formação de Anticorpos , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Feminino , Doenças dos Cavalos/imunologia , Cavalos , Meningoencefalomielite Ovina/imunologia , Masculino , Ovinos , Viremia/etiologia , Viremia/imunologia , Viremia/veterináriaRESUMO
The course of louping-ill virus infection in mice chronically infected with Trypanosoma brucei was investigated. The mean survival time of mice infected with virus alone was 10.2 days, compared to 12.8 days in mice infected with T. brucei 14 days before virus challenge, and the cumulative mortality in the two groups was 62.5 and 90%, respectively. Virus was only inconsistently detected in the blood of mice given virus alone but was regularly present at high titers for up to 12 days in the blood of mice previously infected with T. brucei. Titers of virus in brains were also higher in dually infected mice, and encephalitis was of greater severity. These results indicate that the immunosuppressive effect of chronic trypanosomiasis may markedly increase susceptibility to acute virus infection. In addition, it is concluded that vector-vertebrate relationships of arthropod-transmitted viruses may be altered by concurrent trypanosome infection.
Assuntos
Terapia de Imunossupressão , Meningoencefalomielite Ovina/imunologia , Tripanossomíase Africana/imunologia , Animais , Anticorpos Antivirais/análise , Sangue/microbiologia , Encéfalo/microbiologia , Encéfalo/patologia , Vírus da Encefalite Transmitidos por Carrapatos/crescimento & desenvolvimento , Meningoencefalomielite Ovina/complicações , Meningoencefalomielite Ovina/microbiologia , Camundongos , Ovinos , Trypanosoma brucei brucei , Tripanossomíase Africana/complicações , Tripanossomíase Africana/microbiologiaRESUMO
The influence of colostrum-derived antibody to louping-ill virus on the course of experimental infection was investigated in lambs. Lambs that had high titres of antibody were refractory to infection. Lambs that had low titres of antibody did not develop a viraemia but either showed an antibody reaction or were sensitized as judged by the immune response, which was typical of an anamnestic response, after rechallenge. Animals that had no antibody 34-20 days before challenge had either no or very slight viraemia, but did develop an antibody response with titres as high as those of control lambs by day 21. Lambs that had been negative for longer periods responded in a similar fashion to controls. These findings are discussed in relation to the occurrence of disease in lambs kept in louping-ill endemic areas. It is concluded that in such areas infections of lambs are likely to be of minor importance as a cause of mortality and of little epidemiological significance.