Pathogenesis and transmissibility of highly (H7N1) and low (H7N9) pathogenic avian influenza virus infection in red-legged partridge (Alectoris rufa)

ABSTRACT: An experimental infection with highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian influenza virus (LPAIV) was carried out in red-legged partridges (Alectoris rufa) in order to study clinical signs, gross and microscopic lesions, and viral distribution in tissues and viral shedding. Birds were infected with a HPAIV subtype H7N1 (A/Chicken/Italy/5093/1999) and a LPAIV subtype H7N9 (A/Anas crecca/Spain/1460/2008). Uninoculated birds were included as contacts in both groups. In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi. The presence of viral antigen in tissues and viral shedding were confirmed by immunohistochemistry and quantitative real time RT-PCR (qRRT-PCR), respectively, in all birds infected with HPAIV. However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges. In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals. The present study demonstrates that the red-legged partridge is highly susceptible to the H7N1 HPAIV strain, causing severe disease, mortality and abundant viral shedding and thus contributing to the spread of a potential local outbreak of this virus. In contrast, our results concerning H7N9 LPAIV suggest that the red-legged partridge is not a reservoir species for this virus.     

Emesis in birds

Comparative studies of emesis in the herring gull, pigeon, chicken, and cowbird were conducted, using orally administered copper sulfate and intravenously administered copper sulfate, hydergine, apomorphine, and lanatoside C. A response to every emetic was elicited from some birds. However, the individual and species differences among the birds were as great as those among mammals. Further, the response of the avian species studied did not indicate that any of them could be used to predict how a specific mammal would react. The differences in response to the emetics by the birds do not offer any simple pattern related to feeding behavior.     

Effect of a prebiotic on performance of partridge

An experiment was conducted to investigate the effect of a prebiotic on performance of partridge. The experiment was carried out with a total of eighty‐day‐old male Chukar partridge (Alectoris chukar chukar) chicks in a completely randomized design. The dietary treatments consisted of a control and an experimental treatment, and each treatment was replicated four times with 10 chicks per replicate. The experimental period lasted 16 weeks with a starter period (0–8 weeks) and a grower period (9–16 weeks). The control group was fed the basal diet, while the experimental group was fed the basal diet supplemented with 0.18% prebiotic Aspergillus meal in each period. Performance parameters included body weight gain, cumulative feed consumption and cumulative FCR and were recorded at biweekly intervals. Carcass characteristics and blood parameters were measured at the end of the experiment (week 16). Although the results showed that prebiotic had no significant effect on body weight gain and cumulative feed conversion ratio; however, the supplementation of Aspergillus meal significantly (p < 0.05) decreased cumulative feed consumption. Also prebiotic significantly increased percentages of breast and gastrointestinal tract, decreased percentage of back‐neck, decreased blood triglyceride and total cholesterol content and increased blood calcium content. From this study, it was concluded that dietary supplementation of 0.18% Aspergillus meal might offer beneficial effects on partridge feed consumption, carcass quality and blood cholesterol.     

Pathogenicity of two recent Western Mediterranean West Nile virus isolates in a wild bird species indigenous to Southern Europe: the red-legged partridge

ABSTRACT: West Nile virus (WNV) is an emerging zoonotic pathogen whose geographic spread and incidence in humans, horses and birds has increased significantly in recent years. WNV has long been considered a mild pathogen causing self-limiting outbreaks. This notion has changed as WNV is causing large epidemics with a high impact on human and animal health. This has been particularly noteworthy since its introduction into North America in 1999. There, native bird species have been shown to be highly susceptible to WNV infection and disease with high mortalities. For this reason, the effect of WNV infection in North American bird species has been thoroughly studied by means of experimental inoculations in controlled trials. To a lesser extent, European wild birds have been shown to be affected clinically by WNV infection. Yet experimental studies on European wild bird species are lacking. The red-legged partridge (Alectoris rufa) is a gallinaceous bird indigenous to the Iberian Peninsula, widely distributed in South Western Europe. It plays a key role in the Mediterranean ecosystem and constitutes an economically important game species. As such it is raised intensively in outdoor facilities. In this work, red-legged partridges were experimentally infected with two recent WNV isolates from the Western Mediterranean area: Morocco/2003 and Spain/2007. All inoculated birds became viremic and showed clinical disease, with mortality rates of 70% and 30%, respectively. These results show that Western Mediterranean WNV variants can be pathogenic for some European bird species, such as the red-legged partridge.     

The influence of colostrum on infection of calves around 7 months of age with Schistosoma mattheei

Thirty red-legged partridges (Alectoris rufa), 5-month-old, were orally inoculated with oocysts of the OV-51/95 strain of Toxoplasma gondii. Birds were distributed into five groups and received, respectively, 10 (group A, 4 birds), 50 (group B, 14 birds), 10(2) (group C, 4 birds), 10(3) (group D, 4 birds) and 10(4) (group E, 4 birds) oocysts. One partridge from group B and one from group E died suddenly of acute toxoplasmosis at 7 day after inoculation (DAI) with demonstrable T. gondii in several tissues. The rest of birds remained clinically normal until killed at 44, 58, 65, 72, 79 or 100 DAI. Brain, heart, liver and skeletal muscle from these partridges were bioassayed individually in mice; T. gondii was demonstrated in all these tissues, except in heart of three birds inoculated, respectively, with 10, 50 and 10(2) oocysts. Lesions were not seen in histologic sections of tissues from surviving partridges. These results suggest that red-legged partridges are resistant to clinical toxoplasmosis.     

Distribution patterns of influenza virus receptors and viral attachment patterns in the respiratory and intestinal tracts of seven avian species

ABSTRACT: This study assessed the presence of sialic acid α-2,3 and α-2,6 linked glycan receptors in seven avian species. The respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, golden pheasant, ostrich, and mallard were tested by means of lectin histochemistry, using the lectins Maackia amurensis agglutinin II and Sambucus nigra agglutinin, which show affinity for α-2,3 and α-2,6 receptors, respectively. Additionally, the pattern of virus attachment (PVA) was evaluated with virus histochemistry, using an avian-origin H4N5 virus and a human-origin seasonal H1N1 virus. There was a great variation of receptor distribution among the tissues and avian species studied. Both α-2,3 and α-2,6 receptors were present in the respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, and golden pheasant. In ostriches, the expression of the receptor was basically restricted to α-2,3 in both the respiratory and intestinal tracts and in mallards the α-2,6 receptors were absent from the intestinal tract. The results obtained with the lectin histochemistry were, in general, in agreement with the PVA. The differential expression and distribution of α-2,3 and α-2,6 receptors among various avian species might reflect a potentially decisive factor in the emergence of new viral strains.     

Bagaza virus is pathogenic and transmitted by direct contact in experimentally infected partridges,but is not infectious in house sparrows and adult mice

Bagaza virus (BAGV) is a mosquito-borne flavivirus belonging to the Ntaya serocomplex. In 2010, a disease outbreak was reported in Cádiz (Southern Spain) affecting game birds (red-legged partridges and common pheasants). In this work, red-legged partridges were inoculated experimentally with infectious BAGV isolated from this outbreak in order to make a complete clinical and analytical assessment of the disease caused by the pathogen in this species. Viral load (by real-time RT-PCR) in blood, oral and cloacal swabs, and feathers, and neutralizing antibody titres (by VNT) were measured. In order to determine direct contact transmission, non-inoculated partridges were caged together with the inoculated ones. To assess infectiousness in other species, house sparrows and mice were also inoculated with the virus. All the inoculated partridges were clinically affected, and 30% of them died. All the infected individuals lost weight, with larger losses being recorded in females. Conversely, no mortality or disease symptoms were observed in the sparrows or mice. Remarkably, all the contact partridges acquired the infection by direct (non-vectored) transmission. This study confirms that the red-legged partridge is a susceptible host for BAGV infection, and that this pathogen is transmitted by direct contact. Long-lasting viral loads detected in calami of immature feathers demonstrate that feather sampling could be a useful strategy in active surveillance programs for early detection of BAGV.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0233-9) contains supplementary material, which is available to authorized users.     

Anti-predator behaviour of adult red-legged partridge (Alectoris rufa) tutors improves the defensive responses of farm-reared broods

1. The aim of this work was to improve natural anti-predator behaviour of farm-reared gamebirds.

2. We evaluated the anti-predator behaviour of reared red-legged partridge Alectoris rufa chicks kept in brooder houses in large groups (>350 chicks), trained and not trained by parent red-legged partridges acting as experienced tutors.

3. The experiment consisted of two conditioned tests (a raptor model and a human) and two control tests, which were conducted during three consecutive phases of life (1–4, 15–17 and 30–32 d after hatching). The motor anti-predator behaviour, its duration, the intensity of response in chicks and alarm calls elicited by adults were recorded.

4. Tutors elicited aerial alarm calls (76% of tests) and showed prolonged crouching (59% of tests) in response to the raptor model whereas uttering the ground alarm call (73% of tests) and showing vigilance behaviour (78% of tests) was the main pattern during the human test.

5. Trained and not trained chicks showed similar motor behaviour in response to the raptor model (crouching) and the human test (escaping), but frequency of strong responses (all chicks responding) from chicks trained with tutors was double that of chicks trained without them, and chicks trained with tutors showed a higher frequency of long responses (41–60 s).

6. This study indicates that anti-predator training programmes before release may improve behaviour of farm-reared partridges which may confer benefits to survival of birds.

     

Isolation from predators: a key factor in the failed release of farmed red-legged partridges (Alectoris rufa) to the wild?

1. The effects of predation isolation were studied in two lines of 10 month-old farmed red-legged partridges (Alectoris rufa). Birds came from bred generations in captivity (F) and directly from wild parents (W). 2. Releases were carried out in March for two consecutive years on private farmland with a stable population of wild red-legged partridge using 68 tagged birds (36 F, 32 W). 3. No statistical differences were found in survival time (mean 18 d) or home range values (mean 7·38 ha); 49% of mortality was attributable to raptors, 36% to wild canids and 15% had doubtful causes of death. F birds suffered more predation by raptors and W partridges more by mammalian carnivores. 4. A statistical difference was found in post-release dispersion: the means were 243·4 m in F and 593·3 m in W. 5. The result of predation isolation was similar in both groups, which confirms the adverse effects of current production systems on anti-predator behaviour. Farmers should consider the introduction of new rearing techniques with the aim of improving survival after release.     

Residues of DDE and PCB in eggs from herrring gull (Larus argentatus) and common gull (Larus canus) in Norway

In 1969 294 eggs from herring gull were collected from eight different localities in Norway. The eggshell thicknesses were measured, and 10 eggs from each locality were analysed by gas liquid chromatography for organochlorine insecticides and polychlorinated biphenyls (PGB).Residues of DDE were demonstrated in all eggs, the concentrations varying from 0.2 to 5.4 p.p.m. in herring gull, and from 0.2 to 3.5 p.p.m. in common gull. DDT occurred only in four eggs from herring gull and then only in concentrations of from 0.1 to 0.3 p.p.m. Other organochlorine insecticides were not detected. Residues of PGB were found in all eggs from herring gull in concentrations of from 0.2 to 3.8 p.p.m. PGB 10, and in six out of nine eggs from common gull, from trace to 0.8 p.p.m. PGB 10.The analysed material showed a positive correlation between amounts present of DDE and of PGB.There was a significant difference between localities concerning the contents of DDE and PGB in eggs from herring gull. This variance may be taken into consideration by using the herring gull as an indicator organism, since this bird, especially in the northern part of Norway, is migratory.The residue concentrations of DDE and PGB were markedly higher in eggs from herring gull than in eggs from common gull. It is suggested that this may be related to the difference between these species in their feeding habits.The residues of organochlorines demonstrated in this investigation do not seem to have had any effect on eggshell thickness in herring gull.     

Induced systemic listeriosis in Alectoris chukar chicks: clinical,histopathological and microbiological findings

1. Systemic listeriosis was induced in 14-d-old Chukar partridge chicks, Alectoris chukar, by intravenous injection of a suspension containing 10⁶ cfu/ml of viable Listeria monocytogenes organisms to study the course of infection.

2. Septicaemic and encephalitic forms of listeriosis were observed in all birds. Infection resulted in a fever response 8-h post-inoculation. Disease rapidly developed over a 24-h period with decreased activity, lethargy, ruffled feathers, huddling, listlessness, inability to stand, wing droop, decreased feed and water consumption, growth depression, neural disturbances and finally death. Gross and histopathological changes were observed in the myocardium, proventriculus, gizzard, intestine, pancreas, kidney, liver, spleen, lung, meninges and joints.

3. The diversity of these clinical signs and lesions suggests a high susceptibility of Chukar partridge chicks to systemic listeriosis.     

Growth and development of chicks of two species of partridge: the grey partridge (Perdix perdix) and the chukar (Alectoris chukar)

1. In two partridge species, the grey partridge (Perdix perdix) and chukar (Alectoris chukar), from hatching up to 120?d, the growth rate and development of body mass, wing, tarsus, and bill length were measured and fitted by Gompertz equations.

2. As a typical precocial species, partridges hatched with relatively well developed legs and bills, and wing growth followed a gradual development of thermoregulation.

3. Gompertz growth constants for body mass growth were 0·039 and 0·038 for grey partridges and chukars, respectively.

4. The allometric relationship between tarsus length and body mass followed a geometric similarity (1/3 power) in both grey partridges and chukars.     

The current status of avian aspergillosis diagnoses: Veterinary practice to novel research avenues

Aspergillus fungal infections continue to be a significant cause of morbidity and mortality in birds that can, in part, be attributed to the lack of a diagnostic “gold standard” for Aspergillus infection, and which delays the diagnosis, treatment, and outcome of avian patients. At present, none of the available methods in veterinary care can detect aspergillosis early enough and with the accuracy, precision, and specificity required of an ideal diagnostic tool. Therefore, researching methods of Aspergillus detection is still an active area of inquiry, and novel techniques continue to emerge. This review will provide a brief overview of current clinical methods, with an emphasis on avian care, in addition to a series of techniques in development that could offer distinct advantages over existing methods.     

Absence of protection from West Nile virus disease and adverse effects in red legged partridges after non-structural NS1 protein administration

The red-legged partridge (Alectoris rufa) is a competent host for West Nile virus (WNV) replication and highly susceptible to WNV disease. With the aim to assess in this species whether the inoculation of non-structural protein NS1 from WNV elicits a protective immune response against WNV infection, groups of partridges were inoculated with recombinant NS1 (NS1 group) or an unrelated recombinant protein (mock group), and challenged with infectious WNV. A third group received no inoculation prior to challenge (challenge group). The NS1 group failed to elicit detectable antibodies to NS1 while in the mock group a specific antibody response was observed. Moreover, no protection against WNV disease was observed in the NS1 group, but rather, it showed significantly higher viral RNA load and delayed neutralizing antibody response, and suffered a more severe clinical disease, which resulted in higher mortality. This adverse effect has not been observed before and warrants further investigations.     

Genetic effects of vascular endothelial growth factor and its receptor 2 on feather maturity in three chicken breeds

1. The goal of the current study was to evaluate the genetic effects of the vascular endothelial growth factor (VEGF) and its receptor (VEGFR-2) on feather maturity in the Qingyuan partridge chicken, Guangxi sanhuang chicken and Princess chicken.

2. Both SSCP-PCR and qPCR were employed to detect the polymorphism and gene expression of the VEGF and VEGFR-2 genes.

3. Four SNPs were identified in the VEGFR-2 gene. Exon10-A69G was associated with feather maturity (P < 0.01). Princess chickens with the genotype EF had higher feather maturity scores (P < 0.01). Higher expression levels of VEGF and VEGFR-2 were detected in the immature feather group of Qingyuan partridge chickens, especially in the skin.

4. The VEGF and VEGFR-2 genes play critical roles in feather maturity. In addition, exon10-A69G and genotype EF in the Princess chicken could potentially be utilised as genetic markers to improve efficiency in breeding.     

Study of survival, dispersal and home range of autumn-released red-legged partridges (Alectoris rufa)

1. On a private property with a stable population of wild red-legged partridge (Alectoris rufa) and an appropriate habitat for the survival of the species, reinforcement repopulations were carried out in the months of October and November for two consecutive years using 5- to 6-month-old birds reared on a commercial game farm. 2. Of the 36 released birds, none was still alive by the following spring's breeding period. Mean survival time was 9.4 d in the first year and 7.6 d in the second year. 3. Seventy-two per cent of mortality was attributable to predation, 11% to hunting and 17% to doubtful causes of death, accidents and starvation. 4. Post-release mean dispersion was 377.8 m in the first year and 526.3 m in the second. Mean home range was 7.1 ha in the first year and 5.4 ha in the second. 5. The production systems and handling practices of commercial game farms may have modified some anti-predator ethological patterns and strategies, which might make it more difficult for the birds to adapt and integrate into the wild, resulting in reduced survival due to premature mortality.     

The eggs of some blood-flukes (Trematoda: Schistosomatidae) from South African birds

The eggs of three species of avian schistosomes were recovered from indigenous South African birds. Gigantobilharzia sp. was recorded from the kelp gull, Larus dominicanus and the gannet, Morus capensis; Austrobilharzia sp. from L. dominicanus, and Trichobilharzia sp. from the spurwing goose, Plectropterus gambensis, the Egyptian goose, Alopochen aegyptiacus and L. dominicanus. The morphology of these eggs is compared to that of described species of avian schistosomes.     

Demonstration of Infectious Taura Syndrome Virus in the Feces of Seagulls Collected during an Epizootic in Texas

Abstract

Laughing gulls Larus atricilla were observed feeding on diseased shrimp Penaeus vannamei during an epizootic of the Taura syndrome virus (TSV) at a south Texas farm in May 1995. Fresh fecal samples were collected from a gull roosting site on a pond levee where gulls that fed on diseased shrimp had roosted overnight. The feces samples were tested for the presence of TSV by injection bioassay. A cell-free clarified homogenate of the fecal material was injected into indicator P. vannamei, and the shrimp were observed for 9 d. Cumulative mortalities of the two replicate groups of indicator shrimp were 45% and 70%. Moribund indicator shrimp collected and preserved for histological examination exhibited lesions pathognomonic for acutephase infections by TSV. The presence of TSV in the induced lesions was confirmed with in situ hybridization with cDNA probes specific for a portion of the TSV genome. The presence of infectious TSV in the gulls' feces supports the hypothesis that these birds are a probable transport vector of the virus within and among nearby shrimp farms.     

Studies on Cellulitis and Other Disease Syndromes Caused by Escherichia coli in Broilers in Sri Lanka

Cellulitis caused by Escherichia coli in broilers results in substantial losses to the broiler industry in North America and Europe due to condemnations at slaughter. The objective of this study was to identify cellulitis in broilers in Sri Lanka and to characterize the E. coli from cellulitis and other colibacillosis lesions. Twenty-four farms from the low- and mid-country were selected and bacterial isolations were obtained from 241 birds. Two hundred and ninety-one gross lesions were observed in these 241 birds and 162 E. coli isolates were obtained. Cellulitis was observed in 21% of the birds. Twenty-one per cent of the birds had multiple lesions due to E. coli. The frequency of detection of other disease syndromes was 162 (67%) birds with pericarditis, 26 (11%) airsacculitis, 24 (10%) hepatitis, 12 (5%) perihepatitis, and 16 (7%) polyserositis (a combination of pericarditis, perihepatitis and airsacculitis). Serogroups O78, O2, O85 and O88 were distributed among the 32% of typable E. coli and 81% of isolates were assigned to three biotypes. Forty-four per cent of the E. coli isolates produced aerobactin and 88% demonstrated resistance to the bactericidal effect of normal chicken serum. The majority of the E. coli isolates were resistant to the antibiotics commonly used in poultry. All the E. coli isolates were non-haemolytic and 25% of the isolates produced K1 capsule. This study demonstrated the presence of cellulitis in Sri Lanka and this report describes some of the phenotypic characteristics of the E. coli isolates.