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1.
J Comp Pathol ; 125(4): 292-303, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11798246

ABSTRACT

Post-weaning multisystemic wasting syndrome (PMWS) is a comparatively new disease of swine, and known to occur in France since 1996. A porcine circovirus type 2 (PCV2) is found in the lesions of affected piglets. Six piglets aged 10-13 weeks were obtained from a French PMWS-affected farm. Two showing characteristic signs of PMWS (palor, weakness and emaciation) remained in poor condition and were finally killed 6 and 9 days after their arrival in the experimental unit. Tissue homogenates from these two piglets were used to reproduce mild PMWS in specific pathogen-free (SPF) piglets. This mild PMWS consisted of pyrexia (up to 41.7 degrees C) and growth retardation (up to 30% of weight reduction compared with controls) commencing 1 week after infection and lasting 3 weeks. In seven additional trials, pyrexia, growth retardation and lesions characteristic of PMWS were consistently produced in SPF and conventional piglets. However, only four of 55 inoculated SPF piglets (7.2%) showed severe wasting disease. One died and the others had to be killed 3 to 4 weeks after inoculation. None of the inoculated animals developed antibodies to any common swine viruses or bacteria, but clear evidence of PCV2 seroconversion was obtained. Our results therefore strongly suggest that PCV2 is the primary aetiological agent of PMWS.


Subject(s)
Circoviridae Infections/veterinary , Circovirus/isolation & purification , Disease Models, Animal , Swine Diseases/virology , Wasting Syndrome/veterinary , Animals , Circoviridae Infections/pathology , Circovirus/pathogenicity , Circovirus/physiology , Fever/veterinary , Fever/virology , Growth/physiology , Reproducibility of Results , Specific Pathogen-Free Organisms , Swine , Swine Diseases/pathology , Wasting Syndrome/etiology , Wasting Syndrome/pathology , Weaning
2.
Vaccine ; 18(17): 1738-42, 2000 Mar 06.
Article in English | MEDLINE | ID: mdl-10699321

ABSTRACT

In neonates, one limitation of vaccination is its inhibition by maternal antibodies. We show that piglets vaccinated intramuscularly once at birth with recombinant replication-defective adenoviruses developed comparable neutralizing antibody response against pseudorabies virus, independently of the presence or absence of maternal antibodies, and were partially protected against challenge 16 weeks later.


Subject(s)
Adenoviridae/immunology , Immunity, Maternally-Acquired/immunology , Pseudorabies/prevention & control , Swine Diseases/prevention & control , Vaccines, Synthetic/immunology , Viral Vaccines/administration & dosage , Viral Vaccines/immunology , Adenoviridae/genetics , Administration, Intranasal , Animals , Animals, Newborn , Antibodies, Viral/blood , Dose-Response Relationship, Immunologic , Enzyme-Linked Immunosorbent Assay , Herpesvirus 1, Suid/genetics , Injections, Intramuscular , Mice , Pseudorabies/blood , Pseudorabies/immunology , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Swine , Swine Diseases/blood , Swine Diseases/immunology , Vaccines, Synthetic/administration & dosage , Viral Envelope Proteins/genetics , Viral Envelope Proteins/immunology
3.
Vet Immunol Immunopathol ; 61(1): 49-66, 1998 Feb 16.
Article in English | MEDLINE | ID: mdl-9613472

ABSTRACT

In three successive experiments, the immune functions of pigs persistently infected with the porcine reproductive and respiratory syndrome virus (PRRSV) have been evaluated. Non-specific immune responses were analyzed over a period of 12 weeks post-infection (PI). In addition, the capacity of PRRSV-infected pigs to develop an efficient immune response against pseudorabies virus (PRV) glycoproteins and to resist to a subsequent virulent challenge was investigated. Our results demonstrate that PRRSV produced minor effects on the immune system of pigs. The skin delayed type hypersensitivity (DTH) in response to phytohemagglutinine injection was slightly diminished one week after challenge, but was restored thereafter. However, three weeks after the infection, the total white blood cell count, and the number of CD2+, CD8+ and IgM+ cells were enhanced. The increase in numbers of CD8+ cells persisted for three consecutive weeks. Serum immunoglobulins in infected pigs also increased by week 3 PI and up to 8 weeks PI. These results show that PRRSV may have stimulating effects on the pig immune system during the phase of long-lasting infection. After immunization with PRV glycoproteins, the production of anti-PRV antibodies and skin DTH response against PRV glycoproteins were not affected. On the contrary, following a virulent PRV challenge, PRRSV-infected pigs developed a better secondary antibody response and their resistance to the infection was as effective as in control pigs. Taken together, our data do not support a systemic immunosuppressive effect of PRRSV, during the persistent phase of infection. Other mechanisms may therefore apply to explain the emergence of secondary infections in endemically infected herds.


Subject(s)
Antibodies, Viral/analysis , Porcine Reproductive and Respiratory Syndrome/immunology , Porcine respiratory and reproductive syndrome virus/immunology , Swine Diseases/immunology , Swine/immunology , Animals , Blood Cell Count/veterinary , CD2 Antigens/immunology , CD4-CD8 Ratio , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Enzyme-Linked Immunosorbent Assay/veterinary , Hypersensitivity, Delayed/immunology , Immune System , Immunoglobulin M/analysis , Porcine respiratory and reproductive syndrome virus/pathogenicity , Skin/immunology , Viremia/immunology , Viremia/veterinary
4.
Zentralbl Veterinarmed B ; 39(9): 683-91, 1992 Nov.
Article in English | MEDLINE | ID: mdl-1337234

ABSTRACT

Six isolates originating from acute outbreaks of infectious bursal disease recently reported in broiler and pullet flocks in France were studied with respect to their pathogenicity and their antigenic relatedness to the Faragher 52/70 reference strain. Although the mortality experimentally induced in susceptible chickens by the field strains was sometimes four times higher than that which followed the inoculation of the reference strain (16 to 48% versus 12%), neither mortality nor morbidity were observed in chickens previously vaccinated with a commercial live vaccine and then challenged under the same conditions. Agar gel precipitation tests demonstrated the existence of common antigens in the different strains, and high cross-neutralization indices measured in embryonated specific pathogen free eggs showed them all to belong to serotype I. These data are discussed with reference to previous European and North-American studies on the antigenic status of infectious bursal disease virus.


Subject(s)
Chickens , Disease Outbreaks/veterinary , Infectious bursal disease virus/pathogenicity , Reoviridae Infections/microbiology , Acute Disease , Animals , Antigens, Viral/immunology , Female , France/epidemiology , Infectious bursal disease virus/immunology , Male , Reoviridae Infections/epidemiology , Specific Pathogen-Free Organisms , Vaccination/veterinary
5.
Avian Pathol ; 20(4): 577-84, 1991 Dec.
Article in English | MEDLINE | ID: mdl-18680055

ABSTRACT

Avoparcin (10 mg/kg feed), bacitracin (50 mg/kg), flavomycin (5 mg/kg) and virginiamycin (20 mg/kg) were tested for their synergy or antagonism on the protective effect of an adult caecal flora administered to 1-day-old chicks. The chicks were challenged experimentally per os with 10(4) to 10(5)Salmonella typhimurium (a rifampicin-resistant strain) when aged 2 days. Chicks receiving avoparcin continuously in the feed had significantly more Salmonella in their caeca than control birds given feed containing no antibiotics; those receiving flavomycin had similar numbers to the controls whereas the groups fed on a diet supplemented with bacitracin or virginiamycin exhibited the lowest level of Salmonella carriage.

6.
Arch Virol ; 105(3-4): 199-208, 1989.
Article in English | MEDLINE | ID: mdl-2546517

ABSTRACT

This report describes an ELISA blocking test using a peroxidase-labelled monoclonal antibody which binds to the HN protein of Newcastle disease (NDV). This test allows specific detection of type 1 avian paramyxovirus (PMV1) antibodies but does not detect other avian paramyxovirus (PMV2-9) antibodies recognized by the usual serological NDV tests (HI, Orgenics, and Agritech ELISA tests). Furthermore, swollen head syndrome and influenza antibodies were also not detected. ELISA blocking and HI titers of sera collected from SPF chickens immunized with 18 different PMV1 strains (including pigeon isolates) were the same; the correlation between ELISA blocking and HI titers was highly significant (P less than 0.001). In comparison with ELISA tests available commercially at the present time, the ELISA blocking test can be performed more quickly and is applicable without modification to sera from different species of fowls. For this reason, the test appears to be useful for determining the immunity and sanitary status of fowls. When recombinant or deleted vaccines become available, the test should make it possible to demonstrate with confidence any infection of fowls by wild type PMV1.


Subject(s)
Antibodies, Monoclonal/immunology , Enzyme-Linked Immunosorbent Assay/methods , Hemagglutinins, Viral/immunology , Newcastle disease virus/immunology , Paramyxoviridae/immunology , Viral Envelope Proteins/immunology , Animals , Antibodies, Viral/immunology , Chickens/microbiology , Ducks/microbiology , Evaluation Studies as Topic , HN Protein , Hemagglutination Inhibition Tests , Newcastle Disease/diagnosis , Paramyxoviridae/isolation & purification , Peroxidase , Reproducibility of Results , Sensitivity and Specificity , Specific Pathogen-Free Organisms
7.
Avian Pathol ; 17(3): 601-15, 1988.
Article in French | MEDLINE | ID: mdl-18766719

ABSTRACT

Five-week-old SPF chickens were inoculated with a virulent strain of M. gallisepticum and half were exposed to an atmosphere containing 100 ppm ammonia. The inoculation reduced weight gain and induced general and respiratory signs (prostration, tracheal rales, and snoring). Tracheal cilial movement was stopped. The severity and duration of M. gallisepticum infection were exacerbated by exposure to ammonia.

9.
Avian Pathol ; 15(3): 367-83, 1986.
Article in English | MEDLINE | ID: mdl-18766539

ABSTRACT

Virological 1 examination of a severe infectious bronchitis (IB)-like field case in laying hens, led to the isolation of a coronavirus antigenically different from Massachusetts, Connecticut and four Dutch IB variant strains. The virulence of the isolate for the fowl, and its dual tropism for the respiratory and genital tracts were demonstrated. In preliminary cross-protection studies Commercial vaccines did not protect against challenge with this isolate. These points and the possible economic significance of the virus are discussed.

10.
Article in French | MEDLINE | ID: mdl-6303682

ABSTRACT

The immunity to infectious bronchitis afforded by spray vaccination of mycoplasma free two days-old broilers with maternal antibodies to infectious bronchitis virus was tested by comparing zootechnical scores, clinical signs, macroscopical and microscopical changes, frequency of infectious bronchitis virus isolation following challenge at one, three and five weeks of age in vaccinated, unvaccinated, challenged and unchallenged birds. This vaccination gave a very good protection to infectious bronchitis for the most part of broiler economical life; growth delays were especially avoided. However, vaccinated and unvaccinated one-week-old birds were not protected enough. No correlation was observed between haemagglutinating antibodies titres and protection. At last this vaccination caused a notable reaction in specific pathogen free control birds of the same age.


Subject(s)
Bronchitis/veterinary , Coronaviridae Infections/veterinary , Poultry Diseases/prevention & control , Animals , Antibodies, Viral/administration & dosage , Bronchitis/immunology , Bronchitis/prevention & control , Chickens , Coronaviridae Infections/immunology , Coronaviridae Infections/prevention & control , Immunity, Maternally-Acquired , Infectious bronchitis virus/immunology , Poultry Diseases/immunology , Vaccination
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