Isolation, characterisation and preliminary cross-protection studies with a new pathogenic avian infectious bronchitis virus (strain PL-84084)

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.

Vaccination of one-day-old chicks against newcastle disease using inactivated oil adjuvant vaccine and/or live vaccine

One-day-old chicks, with or without maternal antibodies against Newcastle disease, were vaccinated by different methods: one group received a live vaccine (Hitchner B1 strain), the second group an oil-adjuvant vaccine, and the third group both vaccines simultaneously. The serological response and the protection of the chicks against challenge were evaluated regularly up to 80 days of age. The best results were obtained when using both vaccines, which induced a good level of protection against the challenge virus strain.

Effect of four antibiotic additives on the Salmonella contamination of chicks protected by an adult caecal flora

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.

Picorna-like viruses of young turkeys: pathogenesis of a disease of poults caused by a picorna-like virus

A strain of picorna-like virus cultivated in the yolk sac membranes of inoculated eggs was inoculated into 6-day-old turkeys. Clinical signs and mortality were observed between two and three weeks. Virus was seen in the faeces. The post-mortem and histological changes in the organs of infected birds were highly suggestive of a viral aetiology. The virus was reisolated from organs of sick and dead poults by inoculating SPF embryonated eggs.

Line differences in resistance to Salmonella enteritidis PT4 infection

1. Four groups of hens, each of a different line, were inoculated at peak of lay, per os in the crop with 1 ml of a suspension containing 10(9) cfu/ml Salmonella enteritidis PT4 (SE). The kinetics of SE contamination in the environment, egg shell and yolk were studied during the first 28 d post inoculation. On the day of slaughter, intestines, caeca, spleen, liver, ovary, oviduct and content were investigated for SE contamination. 2. The commercial egg-type line L2 was found to be the most susceptible to SE. It laid many SE-positive yolks (13.8%) and internal and faecal organs were frequently infected. 3. Certain lines are found to exhibit a degree of resistance to SE; the cause of which is unknown and might be attributed to major genes.

Dose titration study of enrofloxacin (Baytril) against respiratory colibacillosis in Muscovy ducks

Four-week-old specific-pathogen-free Muscovy ducks were inoculated with reovirus. One week later, they were inoculated intratracheally with a O78:K80 strain of Escherichia coli. The next day, they were given enrofloxacin at different doses in the drinking water. Comparison of mortality rates, weight gain, macroscopic lesions, and E. coli re-isolations among treated and untreated birds showed that a 5-day treatment course with 12.5 or 25 ppm enrofloxacin in water for 4 hours in the morning provided good therapeutic efficacy against respiratory colibacillosis.

Evaluation of different turkey rhinotracheitis viruses used as antigens for serological testing following live vaccination and challenge

Two enzyme-linked immunosorbent assays (ELISA) developed in the authors' laboratory for turkey rhinotracheitis serological testing, a commercial ELISA kit, and two virus-neutralization (VN) assays were compared with respect to the efficiency of these assays for serological monitoring in specific-pathogen-free (SPF) turkeys inoculated with four pathogenic isolates of turkey rhinotracheitis virus, with or without previous live vaccination. Both the live vaccine and the different isolates of virus were shown to induce antibody rises, the detectability of which varied depending on the ELISA or VN assay used for serological testing. The results show that 3 weeks after vaccination with an attenuated strain, the choice of an inadequate antigen for serological testing may be the cause of an apparent lack of immunogenicity of the vaccine, and that 2 weeks after challenge, such a choice in ELISA can also hinder the early diagnosis of a TRT virus infection in both vaccinated and unvaccinated turkeys.

Mycoplasma gallisepticum infection in drug-treated chickens: comparison of diagnosis methods including polymerase chain reaction

Ten chickens were inoculated with Mycoplasma gallisepticum (MG) and treated with enrofloxacine. On eight different dates post-inoculation (PI), tracheal swab samples were collected for mycoplasma culture or detection by polymerase chain reaction (PCR), and blood samples were analysed by slide-agglutination test (SA) and enzyme-linked immunosorbent assay (ELISA). Results showed that culture and PCR detected MG from 14/80 or 20/80 samples, respectively. The last culture-positive sample was collected on day 26 PI, whereas PCR still gave positive results on day 54 PI. This difference may be attributed to the high sensitivity of PCR and to its ability to detect non-viable or non-culturable pathogens. Sera were SA positive as early as 5 days PI and some of them remained positive up to day 47 PI. ELISA detected 53 suspicious or positive sera.

Comparison of antigenic and pathogenic properties of Mycoplasma iowae strains and development of a PCR-based detection assay

The six reference strains of Mycoplasma iowae (I, J, K, N, Q and R) and 12 field strains, most of them isolated from turkeys, were studied with a growth-inhibition test and a dot immunobinding test with rabbit antisera to the different serovars of M iowae, 16S rDNA gene amplification by polymerase chain reaction, and pathogenicity for chicken or turkey embryos. Antigenic tests tended to be strain specific and showed that most field strains were closely related to serovars K or N. The two pairs of primers chosen in 16S rDNA guided the amplification of 332 base pairs (bp) or 892 bp fragments from all the M iowae strains tested. All the field strains tested were highly pathogenic for turkey embryos.

[Serologic diagnosis of avian salmonelloses: adjustment of an ELISA test using antigens adsorbed with the aid of anti-colibacillary sera]

A serological ELISA test for diagnosis of avian salmonellosis infections with Salmonella typhimurium or enteritidis has been established. Plates were coated half with a negative antigen and half with a positive antigen. Both negative and positive antigens were adsorbed with a monovalent agglutinant anti Escherichia coli serum prior to being distributed into wells of the plates. Sera from SPF birds and from SPF birds vaccinated and/or inoculated with numerous viruses or bacteria, or sera from conventional birds bacteriologically free of any salmonellosis were tested and the percentage of false positive reactions was inferior than 1%. In groups of birds naturally infected or experimentally inoculated with Salmonella enteritidis or typhimurium the percentages of positive individuals were ranged from 15 to more than 90% according to the doses and routes of inoculation and the delay between contamination and sampling.

Pathogenicity and preliminary antigenic characterization of six infectious bursal disease virus strains isolated in France from acute outbreaks

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.

Efficacy of danofloxacin in the therapy of experimental mycoplasmosis in chicks

Specific pathogen free day-old chicks were inoculated with a virulent strain of Mycoplasma gallisepticum. Birds received either danofloxacin (50 ppm), tylosin (500 ppm) or no medication in the drinking water from 24 hours after infection for three days. The effects of medication on mortality, weight gain, serology, lesions and reisolation of M gallisepticum 21 days following infection were studied. Treatment with danofloxacin and tylosin significantly decreased mortality and increased weight gain compared with infected unmedicated birds. Twenty-one days after infection, M gallisepticum was isolated from 96 per cent of unmedicated birds compared with only 6 per cent of danofloxacin-treated and 40 per cent of tylosin-treated birds, and the percentage showing positive serological tests was reduced from 100 per cent of unmedicated birds to 0 per cent of danofloxacin-treated and 29 per cent of tylosin-treated birds. In both cases, the proportion of positive birds from the danofloxacin-treated group was significantly lower than that from the tylosin-treated group. The occurrence of air sac lesions was also significantly lower in danofloxacin-treated than in tylosin-treated birds.

[Isolation of an adenovirus responsible for a case of pancreatitis in guinea fowl]

Necrotizing pancreatitis is observed in 2 to 4 week-old guinea poult. Virus isolation was attempted from the pancreata of naturally affected birds. The isolate was identified as a type 1 adenovirus, and it reproduced the disease when inoculated to sensible guinea fowl.

An ELISA blocking test using a peroxidase-labelled anti-HN monoclonal antibody for the specific titration of antibodies to avian paramyxovirus type 1 (PMV1)

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.

Characterization of French avian paramyxovirus type 1 (PMV 1) isolates with a Panel of monoclonal antibodies to the Ploufragan strain of Newcastle disease virus

Eight monoclonal antibodies against the Ploufragan strain of Newcastle disease virus were used to characterize 58 virus strains including 29 French isolates. By combining ELISA and haemagglutination inhibition tests, PMV 1 strains were differentiated from other avian PMV 1 and grouped into 7 classes.

[Efficacy of spiramycin and tylosin in preventing mycoplasmosis in chicks experimentally infected with mycoplasma gallisepticum]

In order to evaluate the activity of two drugs (spiramycin and tylosin), one-day-old chicks are inoculated with a virulent strain of Mycoplasma gallisepticum (MG) and given spiramycin (3 different doses) or tylosin (1 dose) for two or three days. Effectiveness is assessed on different criteria: mortality, symptoms, weight gains, gross lesions, MG tracheal recovery and serology. Results show that spiramycin and tylosin have the potential of reducing mortality, symptoms and lesions. Weight gains of treated birds are greater than those of infected untreated birds. However, MG was recovered from tracheas of all treated birds.

Rapid identification of Salmonella from poultry meat products by using 'Mucap Test'

A study was made in order to improve a new Salmonella identification test (Mucap Test) in which umbelliferone is released, giving a blue fluorescent light under a Wood lamp, after contact with Salmonella colonies. The study concerned 354 colonies, previously isolated from 55 poultry meat samples. Two enrichment media [Tetrathionate Bile Broth (TBB) and Rappaport Vassiliadis (RV)] and two isolation media [Brilliant Green Agar (BGA) and Desoxycholate Agar (DA)] were used, and the results of the test obtained respectively with each association were compared. The sensitivity was consistently good, but the specificity of the test was generally poor. The best association seemed to be RV/DA which gave 85% specificity, against 39% for TBB/BGA, 58% for TBB/DA, and 77% for RV/BGA. The predominant genera responsible for false-positive results were Pseudomonas and Proteus Providencia.

[Comparison of sensitivity of four turkey genetic types infected with virulent or attenuated strains of haemorrhagic enteritis virus]

Four turkey genetic strains reacted differently to an experimental infection with different strains, virulent or attenuated, of haemorrhagic enteritis virus. Criteria used were: clinical signs (diarrhoea, mortality), daily weight gain, histopathology and virus recovery in the spleen. Turkeys of one genetic type developed more quickly the disease; the serological response to vaccine using ELISA and agar gel precipitation techniques was also faster. Turkeys of two other genetic types responded later both to the virus and the vaccine. Turkeys of the fourth genetic type responded last. The origin of this discrepancy is discussed.

[Isolation from ducks of a hypervirulent strain of duck plague virus and an avian type 6 paramyxovirus]

This paper describes the isolation and identification of a duck plague virus (DP) and a paramyxovirus (PMV6), from the livers and intestines collected in 4-month old mule ducks, under fattening, exhibiting 75% mortality and necrotic-haemorrhagic gross lesions. These viruses were isolated in specific pathogen free (SPF) muscovy duck eggs and SPF chicken eggs respectively. Then the DP virus was adapted to duck and chicken fibroblasts. The disease was reproduced in 2-week old SPF muscovy ducklings, intramuscularly inoculated with the previous organs, as well as in contact ducks. From them, only the DP virus was isolated again. Experimentally the intramuscular inoculation of the duck plague French vaccinal strain, 4 h post contact, did not prevent the disease and did not decrease its severity. Regarding the DP virus, the typical signs and lesions observed in experimentally infected muscovy ducks as well as the presence of intranuclear inclusions of the epithelial cells of their oesophagus, intestines, bursa of Fabricius and liver on the one hand, and on the other hand, of the epithelial cells of the duck egg chorio-allantoic membrane and fibroblasts inoculated with the samples first defined, allowed the characterization of the virus. Direct electron microscopy, as well as the results of seroneutralization tests with different specific avian Herpes virus antisera confirmed the DP virus identification. Moreover the DP isolate was not antigenically different from the serotype actually known. The haemagglutinating virus (PMV6) was characterized by direct electron microscopy as well as with 18 specific avian Myxovirus antisera; its identification was confirmed too by the specific seroconversion observed 4 weeks post-inoculation of this virus, in 11 weeks old SPF muscovy ducklings. Finally an assay was carried out to appreciate the pathogenicity of theses viruses inoculated either separately or associated. It showed the high pathogenicity of the DP strain. The PMV6 was apathogenic and no synergic effect with the DP virus was demonstrated. It appears to be the first isolation of PMV6 in France, to our knowledge. The epidemiological circumstances related to theses isolations are discussed. The failure of the emergency vaccination in contact ducks, might be attributed to the high virulence of the DP strain.

Influence of resident Salmonella on contamination of broiler flocks

An epidemiological survey was made of 5329 samples from 10 poultry operations to determine the relationship between total poultry farm environment and incidences of Salmonella contamination of broiler flocks. Samples were analyzed from walls, drinkers, feeders, litter, insects, water, chicks, broilers, and feed to determine the effect of common sanitary practices on Salmonella contamination of flocks. Results indicated that although similar hygienic practices had been taken on the 10 poultry farms examined, great variation exists in Salmonella contamination among the farms. Among the sources studied, the most important source of contamination was determined to be the resident Salmonella of the flock i.e., the strain isolated on chicks' first day in the poultry house. This source was more important than Salmonella isolated during the rearing period. However, the precise conditions of Salmonella contamination in poultry flocks remain to be elucidated.

Respiratory disease (rhinotracheitis) in turkeys in Brittany, France, 1981-1982. I. Field observations and serology

During the summer of 1981, a respiratory disease epidemic occurred in turkeys in Brittany, France. Since this initial epizootic, which lasted through fall, epizootic waves similar to the initial one have occurred at approximately 6-month intervals, with smaller peaks at 2-month intervals. The epidemiology, clinical signs, and postmortem findings were highly suggestive of an epizootic of chlamydiosis. Serological tests for chlamydia, paramyxoviruses, avian influenza, adenovirus 127, mycoplasma, and Alcaligenes faecalis were conducted. The chlamydia tests were the only ones consistently positive.

Respiratory disease (rhinotracheitis) in turkeys in Brittany, France, 1981-1982. II. Laboratory findings

After discovering that numerous turkey flocks experiencing rhinotracheitis in Brittany, France, had antibodies against chlamydia, laboratory studies were conducted to determine whether chlamydia and/or viruses would explain the respiratory disease observed. Although both lentogenic paramyxoviruses of type 1 (Newcastle disease virus) and Chlamydia psittaci were isolated, it was concluded, based on epidemiologic and other laboratory findings, that C. psittaci was the primary cause of the disease.

[Vaccination against infectious bronchitis in young chickens--carriers or not of maternal antibodies]

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.