RESUMO
The glycoprotein (GP) and nucleocapsid (NC) genes of Rift Valley fever virus (RVFV) were expressed in different expression systems and were evaluated for their ability to protect mice from virulent challenge using a prime-boost regime. Mice vaccinated with a lumpy skin disease virus-vectored recombinant vaccine (rLSDV-RVFV) expressing the two RVFV glycoproteins (G1 and G2) developed neutralising antibodies and were fully protected when challenged, as were those vaccinated with a crude extract of truncated G2 glycoprotein (tG2). By contrast mice vaccinated with a DNA vaccine expressing G1 and G2 did not sero-convert with only 20% of them surviving challenge. Mice vaccinated with the DNA vaccine and boosted with rLSDV-RVFV also failed to sero-convert but 40% survived challenge. Surprisingly, although none of the mice immunised with the purified NC protein sero-converted, 60% of them survived virulent challenge. The rLSDV-RVFV construct was then further evaluated in sheep for its dual protective abilities against RVFV and sheeppox virus (SPV). Vaccinated sheep sero-converted for both viruses and were protected against RVFV challenge, however, neither the immunised or negative control animals showed any significant reactions to the virulent SPV challenge.
Assuntos
Febre do Vale de Rift/prevenção & controle , Febre do Vale de Rift/veterinária , Vírus da Febre do Vale do Rift/imunologia , Vacinas Virais/uso terapêutico , Animais , Antígenos Virais/biossíntese , Antígenos Virais/isolamento & purificação , Temperatura Corporal/fisiologia , Sistemas de Liberação de Medicamentos , Ensaio de Imunoadsorção Enzimática , Feminino , Esquemas de Imunização , Imunização Secundária , Masculino , Camundongos , Camundongos Endogâmicos BALB C , RNA Viral/imunologia , Febre do Vale de Rift/imunologia , Ovinos/imunologia , Vacinas de DNA/administração & dosagem , Vacinas de DNA/uso terapêutico , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/uso terapêutico , Vacinas Virais/administração & dosagemRESUMO
Diagnosis of Rift Valley fever (RVF) is based on serology and virus isolation. The disadvantages of the former include poor sensitivity, high cost, risks associated with using infectious virus as antigen, the lengthy duration of ELISA as well as cross-reactivity with other Phleboviruses. We developed, optimised and evaluated a one-tube reverse-transcription-polymerase chain reaction (RT-PCR) for the detection of Rift Valley fever virus (RVFV) in ruminants. The PCR primers for this assay were designed to anneal to a region within the M segment of the virus genome, encoding glycoproteins G1 and G2. A PCR amplicon of 363 bp was obtained. The sensitivity of the assay was determined to be 0.25 TCID50. This test should allow for the early and rapid detection of RVFV in both serum and whole blood. In addition, it could facilitate the quantification of antigen for the manufacture of current vaccines.
Assuntos
Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Febre do Vale de Rift/veterinária , Vírus da Febre do Vale do Rift/isolamento & purificação , Ruminantes , Animais , RNA Viral/sangue , Reprodutibilidade dos Testes , Febre do Vale de Rift/diagnóstico , Vírus da Febre do Vale do Rift/genética , Sensibilidade e EspecificidadeRESUMO
Massive growth was observed in mesometrial arteries supplying the placenta of the guinea pig in the first 60 days of pregnancy. The wet weight of the vessel wall increased 50 times, with an almost constant protein concentration. The DNA content rose 30 times. The length of the arteries increased 3.5 times and there was a 13-fold increase in the cross-sectional area of the wall. The changes in cross-sectional area were most pronounced in the peripheral part of the vessel. The observed changes followed an exponential time course. Histological sections showed proliferation, particularly of connective tissue with collagen fibres, while the synthesis of elastic material was suppressed. After parturition, involution with reduction of internal diameter occurred with a half-time of around five days.
