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J G van Bekkum

Publications and source records attributed to J G van Bekkum.

At least 19 recordsLinked to original sources
PubMed1987

[Foot and mouth disease--then, now and in the future].

Foot-and-mouth disease was a problem as early as 1862; however, insights into the aetiology and particularly the concept of infectious disease had not yet been elaborated. Our knowledge and the possibilities of dealing with the disease have shown a spectacular increase since then. Foot-and-mouth disease is now under control in large parts of Europe; this is the result of strict measures and mass vaccination of cattle. However, the situation is unstable, as is testified to by the situation in Italy, and there are questions regarding the origin of sporadic cases of the disease. The main question is: how do we reach the ultimate objective: a Western Europe free from foot-and-mouth disease, and where annual vaccination of cattle no longer is applied? The problems are analysed. An international approach appears to be essential.

Animals↗
PubMed1984

The thermal death time curve for foot-and-mouth disease virus contained in primarily infected milk.

Whole and skim milk obtained from cows after intramammary and intravenous inoculation with foot-and-mouth disease virus (primarily infected milk) were exposed to various temperatures ranging from 80 to 148 degrees C for various times ranging from 2.5 s to 27 min then tested for viral infectivity. The average pretreatment titre of the 53 lots of milk used was 10(5.9) plaque-forming units of virus per millilitre 10(3.7)-10(6.8)). A thermal death time curve was plotted using the data obtained. The curve demonstrates that in order to inactivate the virus, times of over 20 min are necessary at 'low' temperatures (100 degrees C) while 2.5 s is sufficient at a temperature of 148 degrees C.

Animals↗
PubMed1980

Aspects of heat inactivation of foot-and-mouth disease virus in milk from intramammarily infected susceptible cows.

In skim milk obtained from susceptible cows after intramammary and intravenous inoculation (primary infected milk), foot-and-mouth disease (FMD) virus type O1 was slower inactivated by heat treatment than virus that had been added to pre-exposure skim milk. Residual virus infectivity in heated primary infected milk was more efficiently detected in bovine thyroid cell cultures than in secondary pig kidney (PK2) cell cultures. Untreated primary infected milk was found to inhibit both FMD-virus and vesicular stomatitis virus plaque formation in PK2 cells, suggesting the presence of interferon. The results of further tests confirmed that the interfering activity in unheated primary infected milk was indeed caused by an interferon. Interferon excretion in primary infected milk was investigated using a series of milk samples from three cows. Maximum interferon titres were found after 24 h, coinciding with or shortly after the first virus excretion peak. The results are discussed with particular reference to the use of primary infected milk in studies of the thermal inactivation of FMD-virus.

Animals↗
PubMed1978

Excretion of foot-and-mouth disease virus in oesophageal-pharyngeal fluid and milk of cattle after intranasal infection.

The virus growth in the pharyngeal area and the virus excretion in milk of susceptible and vaccinated dairy cows after intranasal instillation of foot-and-mouth disease (FMD) virus type O1 were examined. Ten vaccinated cows were purchased through a market. Of these, nine had delivered their first calf. The cows were inoculated 2-9 months after having received the last dose of vaccine. All vaccinated cows resisted the intranasal challenge. The virus multiplied in the pharyngeal area but, compared with two susceptible controls, to a limited extent. No clear relation was found between virus growth and the titre of circulating neutralizing antibody at the time of challenge. Virus was first detected in milk samples of the susceptible cows when generalized FMD lesions had developed on day four; the excretion lasted for 3-4 days. Up to 19 days after inoculation untreated milk of the vaccinated cows was examined for the presence of infectious FMD virus. Samples were inoculated onto cell cultures, fed to susceptible pigs and calves and injected intramuscularly and/or intradermolingually into susceptible steers. No infectious FMD virus could be detected, either in cell cultures or in susceptible animals. The animals did not develop neutralizing antibody against FMD virus and were subsequently shown to be fully susceptible to challenge. The results are discussed with particular reference to current problems regarding the export of milk products from countries where vaccination against FMD is practised to countries free of the disease.

Animals↗
PubMed1975

[I.B.R (author's transl)].

The clinical pictures which may be produced by IBR/IPV virus in cattle are briefly reviewed. Up to the autumn of 1972, infection occurred only sporadically in the Netherlands, no typical cases of IBR having been reported up to the fall of that year. Since the winter of 1972-1973 IBR has increasingly been diagnosed, particularly during the winter months. It may, however, be mistaken for other infections of the respiratory tract. The infection apears to be spreading. The clinical features, diagnosis, epizootiology and methods of treatment are discussed. Administration of a vaccine may be indicated in some herds where IBR-virus is present or its introduction is to be expected. In that case, inoculation of a monospecific vaccine, directed against IBR virus only is to be preferred to the use of combination vaccines.

Animals↗