Riks A. Maas

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Infections with Schmallenberg virus (SBV) are associated with congenital malformations in ruminants. Because reporting of suspected cases only could underestimate the true rate of infection, we conducted a seroprevalence study in the Netherlands to detect past exposure to SBV among dairy cattle. A total of 1,123 serum samples collected from cattle during(More)
Successful immunotherapy with recombinant interleukin 2 (rIL-2) of mice bearing a large burden of lymphokine-activated killer-resistant disseminated SL2 lymphoma is described. When mice were challenged i.p. with 2 x 10(4) SL2 cells on day 0 and treated with daily i.p. injections of 5,000 units rIL-2 on days 3-7, no therapeutic effect was observed. However(More)
Inoculation of influenza (H5N1) into beagles resulted in virus excretion and rapid seroconversion with no disease. Binding studies that used labeled influenza (H5N1) showed virus attachment to higher and lower respiratory tract tissues. Thus, dogs that are subclinically infected with influenza (H5N1) may contribute to virus spread.
International regulations prescribe that the absence of avian leucosis viruses (ALV) in avian live virus vaccines has to be demonstrated. Primary chicken embryo fibroblasts (CEF) from special SPF chicken lines are normally used for detection of ALV. The suitability of the DF-1 cell line for ALV-detection, as alternative for primary CEF, was studied in three(More)
The correlation between the antigen content of inactivated Newcastle disease (ND) oil emulsion-vaccines and the serological response after immunisation was studied. The haemagglutinin-neuraminidase (HN) and fusion (F) proteins of Newcastle disease virus (NDV) were quantified in 33 inactivated oil-adjuvanted ND vaccines using isopropylmyristate(More)
A quantification assay for the Haemagglutinin-Neuraminidase (HN) protein of Newcastle Disease Virus (NDV) has been developed at CIDC-Lelystad as a candidate in vitro potency test for inactivated Newcastle disease (ND) vaccines. In studies performed at CIDC-Lelystad, a high correlation was demonstrated between the results of this candidate in vitro potency(More)
The purpose of this study was to prepare and characterize virosomes and ISCOMs containing envelope proteins of Newcastle disease virus (NDV) and to evaluate their immunogenicity in target animals (chickens). Virosomes were prepared by solubilization of virus with either Triton X-100 or octyl glucoside (OG) followed by detergent removal. Biochemical analysis(More)
Knowledge of the relation between the antigen content of inactivated avian influenza (AI) vaccines, the serological response after vaccination and protection of vaccinated animals is important for the choice of optimal vaccines and vaccination regimes as well as for the assessment of criteria for the licensing of new AI-vaccines. We studied this relation in(More)
The histology of Interleukin-2 induced tumour regression is presented. DBA/2 mice were injected simultaneously ip (intraperitoneally) and sc (subcutaneously) with 2 x 10(4) and 2 x 10(5) syngeneic SL2 lymphosarcoma cells, respectively. After treatment with 20,000 U IL-2 given ip at days 10-14, 50% of these mice survive. Histological analysis of the sc(More)
In 2009 a new influenza A/H1N1 virus strain ("pandemic (H1N1) 2009", H1N1v) emerged that rapidly spread around the world. The virus is suspected to have originated in swine through reassortment and to have subsequently crossed the species-barrier towards humans. Several cases of reintroduction into pigs have since been reported, which could possibly create(More)