A.F.G. Antonis

Publications (7)10.14 Total impact

• Article: Vertical Transmission of Rift Valley Fever Virus Without Detectable Maternal Viremia.

  A F G Antonis, J Kortekaas, J Kant, R P M Vloet, A Vogel-Brink, N Stockhofe, R J M Moormann
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  ABSTRACT: Abstract Rift Valley fever virus (RVFV) is a zoonotic bunyavirus that causes abortions in domesticated ruminants. Sheep breeds exotic to endemic areas are reportedly the most susceptible to RVFV infection. Within the scope of a risk assessment program of The Netherlands, we investigated the susceptibility of a native breed of gestating sheep to RVFV infection. Ewes were infected experimentally during the first, second, or third trimester of gestation. Mortality was high among ewes that developed viremia. Four of 11 inoculated ewes, however, did not develop detectable viremia nor clinical signs and did not seroconvert for immunoglobulin G (IgG) or IgM antibodies. Surprisingly, these ewes were found to contain viral RNA in maternal and fetal organs, and the presence of live virus in fetal organs was demonstrated by virus isolation. We demonstrate that RVFV can be transmitted vertically in the absence of detectable maternal viremia.
  Vector borne and zoonotic diseases (Larchmont, N.Y.) 05/2013; · 2.61 Impact Factor
• Article: Efficacy of three candidate Rift Valley fever vaccines in sheep.

  J Kortekaas, A F G Antonis, J Kant, R P M Vloet, A Vogel, N Oreshkova, S M de Boer, B J Bosch, R J M Moormann
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  ABSTRACT: Rift Valley fever virus (RVFV) is a mosquito-transmitted Bunyavirus that causes high morbidity and mortality among ruminants and humans. The virus is endemic to the African continent and the Arabian Peninsula and continues to spread into new areas. The explosive nature of RVF outbreaks requires that vaccines provide swift protection after a single vaccination. We recently developed several candidate vaccines and here report their efficacy in lambs within three weeks after a single vaccination. The first vaccine comprises the purified ectodomain of the Gn structural glycoprotein formulated in a water-in-oil adjuvant. The second vaccine is based on a Newcastle disease virus-based vector that produces both RVFV structural glycoproteins Gn and Gc. The third vaccine comprises a recently developed nonspreading RVFV. The latter two vaccines were administered without adjuvant. The inactivated whole virus-based vaccine produced by Onderstepoort Biological Products was used as a positive control. Five out of six mock-vaccinated lambs developed high viremia and fever and one lamb succumbed to the challenge infection. A single vaccination with each vaccine resulted in a neutralizing antibody response within three weeks after vaccination and protected lambs from viremia, pyrexia and mortality.
  Vaccine 03/2012; 30(23):3423-9. · 3.77 Impact Factor
• Source

  Available from: kacst.edu.sa

  Article: Rift Valley fever virus immunity provided by a paramyxovirus vaccine vector.

  J Kortekaas, S M de Boer, J Kant, R P M Vloet, A F G Antonis, R J M Moormann
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  ABSTRACT: Rift Valley fever virus (RVFV) causes recurrent large outbreaks among humans and livestock. Although the virus is currently confined to the African continent and the Arabian Peninsula, there is a growing concern for RVFV incursions into countries with immunologically naïve populations. The RVFV structural glycoproteins Gn and Gc are preferred targets in the development of subunit vaccines that can be used to control future outbreaks. We here report the production of Gn and Gc by a recombinant vaccine strain of the avian paramyxovirus Newcastle disease virus (NDV) and demonstrate that intramuscular vaccination with this experimental NDV-based vector vaccine provides complete protection in mice. We also demonstrate that a single intramuscular vaccination of lambs, the main target species of RVFV, is sufficient to elicit a neutralizing antibody response.
  Vaccine 06/2010; 28(27):4394-401. · 3.77 Impact Factor
• Article: Rift Valley fever virus immunity provided by a paramyxovirus vaccine vector

  J.A. Kortekaas, Boer, S.M, J. Kant, R.P.M. Vloet, A.F.G. Antonis, R.J.M. Moormann
  Vaccine 2010 (2010) 28.
• Article: Rift Valley fever virus subunit vaccines confer complete protection against a lethal virus challenge

  Boer, S.M, J.A. Kortekaas, A.F.G. Antonis, J. Kant, Oploo, J.L, P.J.M. Rottier
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  ABSTRACT: Rift Valley fever virus (RVFV) is an emerging mosquito-borne virus causing significant morbidity and mortality in livestock and humans. Rift Valley fever is endemic in Africa, but also outside this continent outbreaks have been reported. Here we report the evaluation of two vaccine candidates based on the viral Gn and Gc envelope glycoproteins, both produced in a Drosophila insect cell expression system. Virus-like particles (VLPs) were generated by merely expressing the Gn and Gc glycoproteins. In addition, a soluble form of the Gn ectodomain was expressed and affinity-purified from the insect cell culture supernatant. Both vaccine candidates fully protected mice from a lethal challenge with RVFV. Importantly, absence of the nucleocapsid protein in either vaccine candidate facilitates the differentiation between infected and vaccinated animals using a commercial recombinant nucleocapsid protein-based indirect ELISA.
  Vaccine 28 (2010) 11.
• Article: RVFV subunit vaccines confer complete protection against a lethal challenge

  S.M. de Boer, J. Kortekaas, A.F.G. Antonis, J. Kant, J.L. van Oploo, P.J.M. Rottier, R.J.M. Moormann, B.J. Bosch
• Article: Rift Valley fever virus immunity provided by a paramyxovirus vaccine vector

  J. Kortekaas, S.M. de Boer, J. Kant, R.P.M. Vloet, A.F.G. Antonis, R.J.M. Moormann
  [show abstract] [hide abstract]
  ABSTRACT: Rift Valley fever virus (RVFV) causes recurrent large outbreaks among humans and livestock. Although the virus is currently confined to the African continent and the Arabian Peninsula, there is a growing concern for RVFV incursions into countries with immunologically naïve populations. The RVFV structural glycoproteins Gn and Gc are preferred targets in the development of subunit vaccines that can be used to control future outbreaks. We here report the production of Gn and Gc by a recombinant vaccine strain of the avian paramyxovirus Newcastle disease virus (NDV) and demonstrate that intramuscular vaccination with this experimental NDV-based vector vaccine provides complete protection in mice. We also demonstrate that a single intramuscular vaccination of lambs, the main target species of RVFV, is sufficient to elicit a neutralizing antibody response.
  Vaccine.