Suppression of behavioural and physiological oestrus in the mare by vaccination against GnRH

OBJECTIVE: To examine the immunogenicity of an equine immunocontraceptive vaccine and its efficacy in controlling hormone-related behaviour. DESIGN: A total of 24 mares at two sites in Australia were vaccinated with an immunocontraceptive vaccine comprising gonadotrophin releasing hormone (GnRH) conjugated to a carrier protein in immunostimulating complex as an adjuvant. Twelve animals at each site received a placebo of adjuvant alone and served as controls for seasonal oestrus, hormonal and behaviour patterns. Animals were observed for injection site reactions, ovarian and follicular activity, and serum levels of antibody, 17beta-oestradiol and progesterone in the weeks following vaccination. Mares were also examined for oestrous behaviour by teasing with a stallion. RESULTS: All mares responded to vaccination. Two weeks following the second vaccination there was a peak in antibody response to GnRH that declined gradually over the following weeks. Commensurate with the elevated anti-GnRH antibody there was a marked effect on ovarian activity with a reduction in 17beta-oestradiol and progesterone levels in the 24 vaccinated mares. There was also a reduction of oestrus-related behaviour as determined by a teaser stallion. This effect lasted a minimum of 3 months and correlated with the initial level of antibody response. CONCLUSION: Following a conventional two-dose immunisation regime this commercially available equine immunocontraceptive vaccine was effective at inhibiting oestrous behaviour for at least 3 months. This vaccine has a high level of safety since there were no significant local reactions nor were there any adverse systemic responses to vaccination.     

Fatal encephalitozoonosis in two koalas

Two young koalas from a fauna park, recently out of the pouch and approximately 6 months old, were found dead with no previous clinical signs or gross lesions. On histopathological examination, large numbers of spores consistent with a microsporidian organism were present intracellularly within the small intestinal mucosa. Electron microscopy and polymerase chain reaction studies (sequencing the 5' end of the SSU RNA gene) identified the organism as Encephalitozoon intestinalis with 100% homology with those of previously reported human isolates. This is believed to be the first report of this organism in a marsupial.     

Investigation of a possible chain of Streptococcus suis infection in a pig breeding community using PCR-based genotyping

Streptococcus (S.) suis plays an important role in pig breeding causing invasive diseases such as meningitis and polyarthritis. Herd problems with Streptococcus suis are common in many pig farms and are frequently characterised by disease outbreaks. In this context, it is often important to identify chains of infection, e.g. between a farrow-to-wean and a grower farm. In the following case report a possible chain of infection among the different farms of a farrow-to-finish system was investigated. In two grower units herd problems with S. suis were present; the mortality was higher than 5 %. It appeared likely, that the streptococci causing these problems were transmitted from a single farrow-to-wean unit to the two different grower farms. In the respective farms swabs were taken from different healthy animals and, in the case of the grower farms, also from the infected animals. Genotypic profiling of strains by a multiplex-PCR and AFLP typing method revealed that two different S. suis pathotypes were responsible for the herd problems. Both pathotypes could not be detected in the farrow-to-wean farm.Thus, a chain of infection originating from the farrow-to-wean farm appeared unlikely. The multiplex PCR was in this case sufficient to elucidate the described problem.     

Genetic characterization, pathogenicity, and protection studies with an avian adenovirus isolate associated with inclusion body hepatitis

An avian adenovirus (AAV) was isolated from liver samples of two 2-wk-old broiler-breeder flocks obtained from grandparents vaccinated at 10 and 17 wks of age with an autogenous inactivated vaccine containing the European AAV 8 (8565 strain) and 11 (1047 strain) serotypes (AAV8/11 vaccine). Affected broiler-breeders exhibited clinical signs and macroscopic and microscopic lesions associated with inclusion body hepatitis (IBH). The isolated adenovirus, identified as Stanford, was molecularly characterized as European serotype 9. The pathogenicity of the Stanford strain was confirmed after inoculation of specific-pathogen-free (SPF) chickens at 1-7 days of age, causing 100% and 20% mortality, respectively. The level of protection against IBH was evaluated in two broiler-breeder progenies from AAV 8/11-vaccinated grandparent flocks and a commercial broiler flock by challenge at 1 or 7 days of age with the AAV 8 and 11 serotypes and/or the Stanford strain. The broiler-breeder progenies and the commercial broiler flock exhibited protection against IBH after challenge. No significant differences in mean body weights were observed at 3 wk of age in any of the evaluated groups. We conclude that broiler-breeder progenies from 30- to 50-wk-old grandparents vaccinated with the AAV 8/11 vaccine were adequately protected against challenge with the AAV 8 and 11 serotypes and the Stanford strain.     

Expert opinion based modelling of the risk of human infection with H5N1 through the consumption of poultry meat in Germany

According to current scientific opinion the risk of human infection with H5N1 via preparation and consumption of poultry meat is negligible.This opinion has not yet been challenged by a formal risk assessment, due to the lack of empirical data. We have developed a scenario pathway model as a conceptual framework for a formal assessment of the H5N1 risk to humans through consumption of poultry meat and parameterise the model using information derived from expert opinions. The aim of this study was to investigate whether the notion of an overall negligible risk via the oral infection route is consistent with ad hoc data and expert opinions on the relevant parameters of the model.The model is mainly based on expert opinion. A stochastic Monte-Carlo simulation was conducted which took into consideration (amongst others) the exposure and infection of chicken (broiler and layer), turkeys, ducks and geese, the probabilities of detection prior to slaughter, virus survival and contamination during slaughter, as well as during the cutting and preparation of meat in commercial plants and in private households, respectively. The empirical consumption pattern for poultry meat in Germany was taken into account in the simulation.The results show that the risk for the individual consumer is practically zero whereas up to 23 cases per year in Germany might occur if the upper (more pessimistic) ranges of the expert opinions apply.The finding of a low but non-negligible risk to the population is discussed in relation to the epidemiological information available from recent outbreaks in South East Asia.     

Evaluation of the effectiveness of two infectious bronchitis virus vaccine programs for preventing disease caused by a California IBV field isolate

Infectious bronchitis virus CA99 serotype was isolated from several broiler flocks in Northern California. The virus caused late-onset respiratory disease and increased airsacculitis condemnation in affected flocks despite the use of an established infectious bronchitis virus vaccination program. An experimental study compared Holland/Arkansas and Massachusetts/Arkansas vaccination protocols to determine the efficacy of commercial infectious bronchitis virus vaccines in reducing respiratory disease and airsacculitis lesions found at processing that were associated with a CA99 field isolate. All vaccination groups were given Massachusetts/Connecticut strains of infectious bronchitis virus vaccines at age 1 day followed by vaccination with either Holland/ Arkansas or Massachusetts/Arkansas vaccine strains at 18 days of age. Birds were challenged at age 31 days with a CA99 field isolate. Gross pathology, histopathology, and virus isolation were evaluated. Chickens vaccinated with Holland/Arkansas had marginally better protection against CA99 challenge than chickens vaccinated with Massachusetts/Arkansas, although differences were not statistically significant.     

Molecular and serologic characterization, pathogenicity, and protection studies with infectious bronchitis virus field isolates from California

In this study, we characterized three variant infectious bronchitis virus (IBV) strains isolated in 2003 and 2004 from broiler chickens in California and compared them to previously isolated California variant viruses and to common vaccine serotypes used in the United States. We conducted genetic, serologic, and pathogenicity studies on all three isolates, then tested different vaccines against one of the viruses. Genetically the three variant IBV strains, designated CA557/03, CA706/03, and CA1737/04, were not related to each other. GenBank BLAST database search and phylogenetic analysis of the hypervariable region of the S1 subunit of the spike gene to determine the most closely related viruses to the three variants showed the CA557/03 variant to be 81.8% similar to the CAV/CA56b/91 whereas the CA706/03 and CA1737/04 variant viruses were only distantly related to Dutch/D1466/81 (72.2%), a vaccine strain used in Europe, and Korea/K142/02 (72.7%), a Korean field isolate, respectively. Cross virus-neutralization testing showed that none of the 2003-04 California IBV variant viruses were serologically related to each other or to Ark, Conn, or Mass vaccine strains. In addition the CA1737/04 isolate was also tested against DE072 and found not to be serologically related. All three variant viruses were pathogenic in 1-wk-old broilers and vaccination with Mass/Conn followed by Holland/Conn provided 80% protection against the CA1737/04 virus. The 2003-04 California variant viruses were not compared with variants isolated in California during 1970s and 1980s because, to our knowledge, no genetic information is available and those viruses are no longer obtainable. This study shows that the CA557/03 virus was distantly related to the CAV-type viruses isolated in California in the early 1990s, but that none of the 2003-04 viruses were similar genetically or serologically to the CAL99-type viruses, indicating that new IBV variants continue to emerge and cause disease in commercial chickens in California.     

Protection of pigs against post-weaning multisystemic wasting syndrome by a recombinant adenovirus expressing the capsid protein of porcine circovirus type 2

Post-weaning multisystemic wating syndrome (PMWS) associated with PCV2 was one of the most costly diseases currently faced by the swine industry. In order to develop a vaccine to control this disease, we previously constructed a recombinant adenovirus expressing the capsid of PCV2. Here, we examined the protection of swine against PMWS by the recombinant adenovirus. Eighteen 32-day-old pigs were assigned to three groups each with six. Group 1 was vaccinated subcutaneously with rAd-Cap and boosted 2 weeks later. Thirty-seven days after first vaccination, Groups 1 and 2 were oronasally challenged with virulent PCV2 isolate, 4 and 7 days later, intramuscularly exposed to keyhole limpet hemocyanin (KLH). Group 3 remained unchallenged but with KLH. The results showed that high level of PCV2-specific ELISA antibody and neutralizing antibody could be induced at 37 days after first vaccination. After challenge, pigs in vaccinated group had no clearly clinical signs, although some of them had increased rectal temperatures (>/=40 degrees C) for short time. The pyrexic phase in vaccinated group was significantly lighter than that in challenge-control group (P<0.05). The relative daily weight gain in vaccinated-challenged group was similar to that in empty control group. But it was significantly high compared to the challenge-control group (P<0.05). Mean while the pathological lesions and virema presented in vaccinated group were milder than those in control group. It indicated that the recombinant adenovirus was able to confer significant protection against clinical disease and reduce pathogenic lesions induced by PCV2 challenge, even though it could not provide complete virological protection. The recombinant adenovirus might be an attractive candidate vaccine for preventing the disease associated with PCV2 infection.     

Phenotypic and genotypic characterization of Paenibacillus larvae isolates

Paenibacillus larvae is the causative agent of American Foulbrood (AFB), a severe disease of honeybees (Apis melifera). The aim of this work was to develop a strategy for the subtyping and the epidemiological analysis of P. larvae. Phenotypic characterisation, susceptibility to several antibiotics, electrophoresis of whole bacterial proteins, rep-PCR, ribotyping and DGGE were assessed using a collection of P. larvae isolates from different Uruguayan and Argentinean locations. Results indicated that there are two P. larvae genotypes circulating in Uruguay ERIC I-BOX A (worldwide distributed) and ERIC I-BOX C (exclusively detected in Argentina until this study). These results suggest that P. larvae isolates had moved between Argentina and Uruguay, probably through the Uruguay River. Patterns of whole bacterial proteins, DGGE and ribotyping did not improve the P. larvae intraspecific discrimination. Antibiotic susceptibility assays showed that 100% isolates were OTC-sensitive and 22% (belonging to ERIC I-BOX A group) were sulfisoxazole-resistant. This work may contribute to the elucidation of basic aspects related to the epidemiology of AFB in Uruguay and in the region.     

The influence of omega-3 polyunsaturated fatty acids feeding on composition of fatty acids in fatty tissues and eggs of laying hens

The paper deals with supplementation of hen diet with oils with increased content of omega-3 polyunsaturated fatty acids (PUFA) and occurrence of fatty acids (FA) in fatty tissues and eggs of laying hens after the respective supplementation. The experiment was carried out on 30 laying hens of ISA BROWN hybrid, divided to three groups (A, B, C). For the period of three weeks the group A was administered flax-seed oil, group B served as a control and group C was fed base rations supplemented with fish oil. In addition to that the diet of groups A and C was supplemented with vitamin E as an antioxidant. Administration of the oils as a source of omega-3 PUFA increased their concentration in both the fatty tissues and egg-yolk which resulted in the change of the ratio of omega-6 and omega-3 PUFA. No influence of flax-seed and fish oil on concentration of alpha-tocopherol in egg-yolk was observed.