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Biomedical subjects

M Pensaert

Publications and source records attributed to M Pensaert.

At least 55 records · Page 3Linked to original sources
PubMed1987

Vaccination of swine against H3N2-influenza field isolates using the human Philippines-strain.

Intratracheal inoculation of 2 Belgian H3N2-influenza viral strains, isolated from sick swine in the field, caused high fever, anorexia and dyspnoea in unvaccinated swine. The strains are related to the human A/Port Chalmers/1/73 (H3N2)-strain. In a limited study, 2 subunit vaccines, both derived from the human A/Philippines/2/82 (H3N2)-strain, were tested for efficacy in protecting swine against these Belgian field isolates. Vaccine A was a commercial vaccine, vaccine B an experimental vaccine. For evaluation of the efficacy of the vaccines, clinical as well as virological parameters were used. It was found that 2 spaced injections of the experimental vaccine (B) resulted in very high serum hemagglutination-inhibition (HI) titres against the Philippines-strain. Nevertheless, only partial protection was obtained, as indicated by the milder clinical signs and the decreased viral replication at challenge. One injection of the experimental vaccine (B) and 2 spaced injections of the commercial vaccine (A) did not result in any protection at challenge, even though moderate HI titres against the Philippines-strain were obtained. It was concluded that if an H3N2-strain is included in vaccines for use in swine, a strain should be selected which is identical or very closely related to the strain(s) prevalent in the swine population of the country in which the vaccine will be used.

Animals↗
PubMed1986

Isolation of a porcine respiratory, non-enteric coronavirus related to transmissible gastroenteritis.

A porcine respiratory, non-enteric virus which is related to the coronavirus transmissible gastroenteritis virus (TGEV) has been isolated in pigs and in cell culture. The isolate was designated TLM 83. It has become very widespread and enzootic among the swine population in Belgium and in other swine raising countries. It causes an infection of the lungs and appears to spread by aerogenic route. It does not replicate in the enteric tract. The experimental infection in conventional and gnotobiotic pigs in isolation remains subclinical. The infection, either experimental or in the field, results in the formation of antibodies which neutralise the classical enteric TGEV. Based on this relationship, this virus is assumed to be a new TGEV-related porcine respiratory coronavirus or TGEV itself which has totally lost its tropism for the enteric tract.

Animals↗
PubMed1984

[Persistence of virus in swine stock and breeding farms following an outbreak of Aujeszky's disease].

On seven fattening farms and seven breeding farms, investigations were carried out to examine whether Aujeszky virus was capable of persisting in particular animal groups or units of the farm as a productive infection following a virologically verified outbreak. After an outbreak on fattening farms, virus persisted temporarily as newly arrived piglets became systematically infected. On the farms on which this could be accurately followed, virus persistence continued for at least 1 1/2 to 2 months. However, this cycle of infection was found to be interrupted on each farm within approximately three months after the outbreak, which resulted in a gradual return to a totally sensitive animal population, so that new outbreaks could occur. On the seven swine breeding farms, virus persistence in the farrowing house was examined by placing seronegative sentinel piglets with sows during the immediate post-partum period. Twelve sentinel piglets were placed in the various farrowing houses for a total period of sixty-seven weeks, during which time 172 sows farrowed. None of these piglets became seropositive during their stay on the breeding farms. The results of this study show that Aujeszky's disease virus did not persist on breeding farms and that the productive infection on fattening farms in only transient following an outbreak. Therefore, it is very likely that new outbreaks of the disease are due to reintroduction of Aujeszky's disease virus on the farm. Though the role of latent carrier animals cannot be totally disregarded, natural reactivation of latent virus is believed an exception rather than the general rule.

Animals↗
PubMed1983

Coronaviridae.

The family Coronaviridae comprises a monogeneric group of 11 viruses which infect vertebrates. The main characteristics of the member viruses are: (i) Morphological: Enveloped pleomorphic particles typically 100 nm in diameter (range 60-220 nm), bearing about 20 nm long club-shaped surface projections. (ii) Structural: A single-stranded infectious molecule of genomic RNA of about (5-7) X 10(6) molecular weight. A phosphorylated nucleocapsid protein [mol. wt. (50-60) X 10(3)] complexed with the genome as a helical ribonucleoprotein; a surface (peplomer) protein, associated with one or two glycosylated polypeptides [mol. wt. (90-180) X 10(3)]; a transmembrane (matrix) protein, associated with one polypeptide which may be glycosylated to different degrees [mol. wt. (20-35) X 10(3)]. (iii) Replicative: Production in infected cells of multiple 3' coterminal subgenomic mRNAs extending for different lengths in the 5' direction. Virions bud intracytoplasmically. (iv) Antigenic: 3 major antigens, each corresponding to one class of virion protein. (v) Biological: Predominantly restricted to infection of natural vertebrate hosts by horizontal transmission via the fecal/oral route. Responsible main for respiratory and gastrointestinal disorders.

Antigens, Viral↗
PubMed1983

Rotavirus excretion in suckling pigs followed under field circumstances.

The enzootic behaviour of porcine rotavirus in swine breeding farms was investigated by determination of the rotavirus excretion pattern in faeces using an enzyme linked immunosorbent assay (ELISA). Three herds were followed for 23, 14 and 9 consecutive weeks respectively and faeces were collected once a week from suckling piglets, weaned pigs and sows. The piglets of nearly all litters were found to excrete rotavirus in faeces before the age of 5-6 weeks. Weaned pigs rarely excreted rotavirus and faeces of sows were always negative. About half of the litters excreted rotavirus during more than one week or showed a recurrent excretion period 3-4 weeks after a first one. The presence of rotavirus group-specific antibodies in milk of sows, as detected by ELISA, did not appear to prevent infection of their piglets. These data may be an indication of the presence of serologically different porcine rotavirus strains within the same herd. Subclinical rotavirus infection occurred often in suckling pigs of all ages. Rotavirus was also found in a high number of fecal samples from pigs with diarrhea, but it was impossible to demonstrate the irrefutable association between the rotavirus infection and the presence of diarrhea.

Animal Population Groups↗
PubMed1982

Enzyme-linked immunosorbent assay for the detection of the coronavirus-like agent and its antibodies in pigs with porcine epidemic diarrhea.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of the coronavirus-like agent in feces of pigs naturally affected with porcine epidemic diarrhea (PED) or experimentally infected with the CV777 isolate. The assay was specific and more sensitive than electron microscopy. An ELISA blocking assay is described for the detection and titration of antibodies. Specific antibody formation was demonstrated in pigs experimentally infected with CV777 and in swine naturally affected in PED.

Animals↗
PubMed1981

Evidence for the natural transmission of influenza A virus from wild ducts to swine and its potential importance for man.

In 1979, epidemics of influenza occurred in pigs in Belgium from which were isolated strains of influenza A (Hsw1N1) virus antigenically closely related to Hsw1N1 strains previously isolated from ducks in North America and the Federal Republic of Germany. This finding is considered as the first supportive evidence that an influenza A virus in an avian species might have been transmitted to mammals.

Animals↗
PubMed1980

Vaccination of pregnant sows against transmissible gastroenteritis with two attenuated virus strains and different inoculation routes.

Two attenuated transmissible gastro-enteritis (T.G.E.) virus strains were used for vaccination experiments in sows. Four different experiments were carried out (see Table 1). In each experiment, 9 sows were vaccinated during pregnancy and 3 sows served as controls. They were kept together in one farrowing house. The sows were due to farrow at about the same time. The sows and their litters were challenged shortly after farrowing by exposing 3 piglets of 2 controls litters to virulent TGE virus. The following vaccination schedules were used (see Table 1): twice intramuscularly with TGE-vac (a commercially available TGE-vaccine), one oral administration followed by an intramuscular vaccination with an attenuated TGE Purdue (Pu) strain, twice orally with Pu strain in enteric coated capsules, and one direct intra intestinal administration followed by 2 intramuscular vaccinations or 3 intramuscular vaccinations with the Pu strain. All sows, except most of those treated with enteric coated capsules, seroconverted demonstrably (Table 2). The geometric mean seroneutralization (SN) titer log 2 varied from 4.1 to 7.5 after the first vaccination and from 7.6 to 10 after the second vaccination. None of the vaccination schedules resulted in an effective lactogenic immunity. The morbidity in the piglets was 100% within 3 to 5 days after challenge. The mortality rate varied from 44 to 80% in litters from vaccinated sows and from 71 to 100% in litters from control sows (see Table 3). Clinical signs were observed in 33.3% of the control sows and in 36% of the vaccinated sows. No correlation was found between the titer of SN antibodies in the sera of the piglets and their survival rate (Table 4). A rapid decrease in antibody concentration was observed, during the first week of lactation in milk samples collected from 4 orally and intramuscularly vaccinated sows (Table 5).

Animals↗
PubMed1980

A seroepizootiologic study of vomiting and wasting disease virus in pigs.

Neutralizing antibodies to Vomiting and Wasting Disease virus were found in 95 per cent of the sera collected from Belgian sows at slaughter. Piglets suckled by immune sows and kept in isolation acquired maternal antibodies; these had disappeared in all the animals at the age of 15 weeks. Most pigs had lost their maternal antibodies at the age of 11 or 12 weeks (respectively 57 per cent or 86 per cent). A serologic study on two conventional breeding farms showed that this passive immunity was replaced by active immunity between the ages of 8 and 16 weeks. No clinical disturbances appeared to be associated with the infection. The present data indicate that Vomiting and Wasting Disease virus persists on the majority of the conventional breeding farms.

Animals↗
PubMed1980

Experimental infection of pigs with a new porcine enteric coronavirus, CV 777.

Cesarean-derived colostrum-deprived and conventionally reared pigs were orally inoculated with the coronavirus-like agent, CV 777, isolate from an outbreak of epizootic diarrhea in swine of all ages. Viral particles detected by electron microscopy in the feces and intestinal contents of inoculated pigs had the typical coronavirus morphology. The present studies provided further evidence that this coronavirus-like agent is different from the two known porcine coronaviruses, transmissible gastroenteritis virus and hemagglutinating encephalomyelitis virus. The experimental infection of pigs with this new agent resulted in vomiting, diarrhea, and dehydration. This coronavirus-like agent was shown to replicate in the epithelial cells covering the small intestinal villi but, unlike transmissible gastroenteritis virus, it also replicated in the epithelial cells covering the large intestinal villi.

Animals↗
PubMed1978

[Possible methods of control of virus disease in swine today and in the future. II. Specific applications (author's transl)].

The four alternatives discussed in the previous paper (5), are applied to a number of virus infections which are common in pigs. The enzootic state of SMEDI enteroviruses, vomiting and wasting virus and parvovirus should be promoted by bringing the young gilts into close contact with the older sow population at a sufficiently early stage. There should preferably not be a change of herd for primiparous sows during pregnancy. In parvovirus infection, maternal immunity may be so prolonged that gilts will only be infected after the time of breeding. Therefore, mating should preferably be postponed until they are nine months of age, unless previous serological tests have shown that they are in a state of active immunity. Considering the present disease situation of swine fever in several continental West European countries and consequently they high number of existing virus sources, compulsory vaccination of sows and fattening piglets is recommended against this virus on an international scale for at least three years. This vaccination can be omitted only after the number of outbreaks has been reduced to a very low level. Vaccination is the only possible alternative left in the combat against Aujezky's disease. Caution is undoubtedly indicated in using live vaccines in these cases. So far, methods have not become available for the effective control of transmissible gastroenteritis and prospects are not encouraging. The possibility of eradication of transmissible gastroenteritis is discussed.

Animals↗
PubMed1978

[Possible methods of control of virus disease in swine today and in the future (author's transl)].

To begin with, possible approaches to the control of virus disease in swine are discussed in general. The choice of a method of control will be decided by various factors such as the ecological and geographical environment of the animal population, the epizootiological behaviour of the causative virus itself as well as economic and political considerations. These consist in definitely freeing the swine population and/or keeping it free from a particular virus, maintaining a particular virus in an enzootic state, promoting this enzootic state within the herd, vaccinating and, finally, combining the above procedures. In conjunction with the trend towards increasingly large piggeries, the equilibrium between natural or specific immunity of the animal population and various viruses is often upset to the advantage of the virus. The pressure of infection will increase unduly and the epizootiological behaviour of the virus in question will not infrequently undergo alterations. Therefore, it is believed that the need for artificially increasing immunity or maintaining it at its current level will constantly increase in the long run. This can only be achieved by frequent vaccination. It is not unlikely that vaccination will remain as the sole and last possibility of effectively controlling various forms of virus disease in pigs.

Animal Husbandry↗