Experimental avian paramyxovirus serotype-3 infection in chickens and turkeys

Avian paramyxoviruses (APMV) are divided into nine serotypes. Newcastle disease virus (APMV-1) is the most extensively characterized, while relatively little information is available for the other APMV serotypes. In the present study, we examined the pathogenicity of two divergent strains of APMV-3, Netherlands and Wisconsin, in (i) 9-day-old embryonated chicken eggs, (ii) 1-day-old specific pathogen free (SPF) chicks and turkeys, and (iii) 2-week-old SPF chickens and turkeys. The mean death time in 9-day-old embryonated chicken eggs was 112 h for APMV-3 strain Netherlands and > 168 h for strain Wisconsin. The intracerebral pathogenicity index in 1-day-old chicks for strain Netherlands was 0.39 and for strain Wisconsin was zero. Thus, both strains are lentogenic. Both the strains replicated well in brain tissue when inoculated intracerebrally in 1-day-old SPF chicks, but without causing death. Mild respiratory disease signs were observed in 1-day-old chickens and turkeys when inoculated through oculonasal route with either strain. There were no overt signs of illness in 2-weeks-old chickens and turkeys by either strain, although all the birds seroconverted after infection. The viruses were isolated predominantly from brain, lungs, spleens, trachea, pancreas and kidney. Immunohistochemistry studies also showed the presence of large amount of viral antigens in both epithelial and sub-epithelial lining of respiratory and alimentary tracts. Our result suggests systemic spread of APMV-3 even though the viral fusion glycoprotein does not contain the canonical furin proteases cleavage site. Furthermore, there was little or no disease despite systemic viral spread and abundant viral replication in all the tissues tested.     

Detection of fowlpox in chickens and turkeys in Germany

The present work outlines molecular diagnostic examinations for detection of poxvirus infection in chickens and turkeys in Germany over a time period of twelve years. Diagnostic samples suspected for fowlpox were investigated using the polymerase chain reaction (PCR) in combination with restriction enzyme analysis (REA) for presence of fowlpox virus (FPV) specific DNA. For a long period of time fowlpox did not play a role in commercial poultry farms in Germany. Beginning in 1999 an increasing number of new infections was identified. During the whole study period FPV specific DNA was detected in 92 out of 192 investigated samples. Positive samples were derived especially from layer hens but also from broiler breeders, turkey breeders, and meat turkeys. Thereby, a differentiation between isolates of chickens and turkeys by restriction enzyme analysis (REA) was not possible. As possible explanations for this reemergence, especially the lack of prophylactic vaccination in the past as well as an increasing number of alternative rearing systems has to be considered. Beginning in 2003, a downward tendency was observed following intensification of prophylactic vaccination.     

Pathogenesis of two strains of avian paramyxovirus serotype 2, Yucaipa and Bangor, in chickens and turkeys

Nine serologic types of avian paramyxovirus (APMV) have been recognized. Newcastle disease virus (APMV-1) is the most extensively characterized virus, while relatively little information is available for the other APMV serotypes. In the present study, we examined the pathogenicity of two strains of APMV-2, Yucaipa and Bangor, in 9-day-old embryonated chicken eggs, 1-day-old specific-pathogen-free (SPF) chicks, and 4-wk-old SPF chickens and turkeys. The mean death time in 9-day-old embryonated chicken eggs was more than 168 hr for both strains, and their intracerebral pathogenicity index (ICPI) was zero, indicating that these viruses are nonpathogenic in chickens. When inoculated intracerebrally in 1-day-old chicks, neither strain caused disease or replicated detectably in the brain. This suggests that the zero ICPI value of APMV-2 reflects the inability of the virus to grow in neural cells. Groups of twelve 4-wk-old SPF chickens and turkeys were inoculated oculonasally with either strain, and three birds per group were euthanatized on days 2, 4, 6, and 14 postinoculation for analysis. There were no overt clinical signs of illnesses, although all birds seroconverted by day 6. The viruses were isolated predominantly from the respiratory and alimentary tracts. Immunohistochemistry studies also showed the presence of a large amount of viral antigens in epithelial linings of respiratory and alimentary tracts. There also was evidence of systemic spread even though the cleavage site of the viral fusion glycoprotein does not contain the canonical furin protease cleavage site.     

Primary isolation and identification of avian rotaviruses from turkeys exhibiting signs of clinical enteritis in a continuous MA 104 cell line

Avian rotaviruses were isolated from turkeys with enteritis using MA 104 cell line. MA 104 cells were suitable for primary isolation and propagation of avian rotaviruses. Trypsin appeared essential for the enhancement of infectivity and the occurrence of cytopathic effect (CPE). Serum neutralization (SN), electron microscopy (EM), and analysis of genomic RNA were done to identify and confirm the identity of rotaviruses. Electrophoretic migration patterns of genomic RNA from avian rotaviruses were examined, and they were compared with those from mammalian rotaviruses. The migration patterns differed between these groups.     

从腺胃肿大病鸡中分离到一株冠状病毒

1998年秋 ,天津市郊区部分鸡场已作新城疫、呼吸型传染性支气管炎、肾病变型传染性支气管炎疫苗免疫的 1～ 2月龄雏鸡发生气喘、拉稀、极度消瘦、生长迟滞等症 ,临诊观察有传染性 ,死亡率约 30 %。鸡主送来病死鸡 ,要求诊断。我们从病料中分离到 1株能使鸡胚发育迟滞 ,胚体蜷曲     

Pathogenesis of rotavirus infection in various age groups of chickens and turkeys: pathology

Various age groups of turkeys, White Leghorn chickens, and broiler chickens were inoculated with turkey rotavirus strain Tu-2 or with chicken rotavirus Ch-2, and the development of rotavirus-induced lesions were evaluated macroscopically and microscopically (light microscopy and scanning electron microscopy). Morphometric evaluations were conducted to determine morphologic changes in the villi of infected turkeys. Macroscopic lesions that were found in turkeys, but not in chickens, consisted of pallor of the intestinal tract and distension of the cecum with frothy or nonfrothy fluid contents. Histologic lesions in turkeys consisted of basal vacuolation of enterocytes, separation of enterocytes from the lamina propria (with subsequent desquamation), villus atrophy accompanied by widening of the lamina propria, scalloping of the villus surface, fusion of the villi, and leukocytic infiltration of the lamina propria. Scanning electron microscopy indicated roughened villus surfaces, distortion of the normal morphologic features of the villi, and loss of microvilli in cells located on the tips of the villi. Most of the lesions disappeared by 8 days after inoculation. Results of the morphometric evaluations indicated that the crypt length had increased and the villus-to-crypt ratio had significantly decreased, compared with that of noninoculated control turkeys. Broilers greater than or equal to 21 days old and White Leghorn chickens greater than or equal to 35 days old had minimal leukocytic infiltration of the lamina propria and minimal loss of microvilli in cells located on the tips of the villi. The loss of microvilli was more extensive in chickens greater than or equal to 119 days old than in younger birds. Generally, turkeys 1 to 112 days old developed more severe lesions than did chickens, and lesions were more pronounced in turkeys at 112 days of age.     

Necropsy of chickens, turkeys, and other poultry

Necropsy of dead or terminally ill birds is a key approach to disease diagnosis. It is important that one establish an orderly, consistent necropsy procedure and evaluate gross lesions as to their likely cause and significance. A very high percentage of farm flock poultry maladies can be diagnosed by gross lesions plus a few simple laboratory procedures, such as direct microscopy, Gram's stain, fecal flotation, and aerobic bacteriology.     

Physical, chemical, and serological characterization of avian rotaviruses

Physical, chemical, and serological characterization of rotavirus isolates from turkeys was done. Cesium chloride (CsCl)-gradient isopycnic centrifugation of infected cell cultures revealed the presence of rotavirus particles of three different densities. They were double-shelled, single-shelled, and core particles. The double-shelled particles had a buoyant density (in CsCl) of 1.34 g/cml3, and that of single-shelled particles in CsCl was 1.36 g/cm3. The buoyant density of core particles in CsCl was greater than 1.40 g/cm3. These rotavirus isolates were not inactivated by chloroform and were relatively stable at pH 3.0. Their replication was not affected by 5-bromo-2'-deoxyuridine. Avian rotaviruses were not completely inactivated by heat treatment of 56 C for 8 hr. All six avian rotavirus isolates examined were antigenically related to each other. However, there was no antigenic relationship between mammalian rotaviruses and the avian rotavirus isolates examined.     

Immunization of chickens and turkeys against avian influenza with monovalent and polyvalent oil emulsion vaccines.

Chickens and turkeys vaccinated with inactivated virus oil-emulsion vaccines containing different concentrations of either 1 (monovalent) or 4 (polyvalent) strains of avian influenza virus (AIV) were challenged-exposed with virulent AIV A/chicken/Scotland/59 or A/turkey/Ontario/7732/66. Four of 6 vaccines protected completely against postexposure mortality. Vaccine valency did not alter the serologic and challenge-exposure responses of chickens vaccinated with AIV A/turkey/Wisconsin/68, which was the virus component common to both monovalent and polyvalent vaccines. The magnitude of the serologic responses and protection against challenge-exposure were dependent on the concentration of virus in the vaccines. These data indicate that control of virulent AIV in chickens and turkeys by vaccination with inactivated vaccines may be feasible.     

Full-length genome analysis of G2, G9 and G11 porcine group A rotaviruses

Group A rotaviruses with G2 and G9 VP7 specificity are common in humans, while G11 strains have been detected only sporadically. G2, G9 and G11 rotaviruses also circulate in pigs and swine rotaviruses have been suspected of interspecies and zoonotic transmissions in numerous studies. However, the complete gene constellation of G2 and G9 porcine rotaviruses has not yet been determined. In order to start filling this gap, the genomic make up of two G2, one G9 and one G11 porcine rotavirus strains, detected in Canada in 2005–2007, was determined. With the exception of a G2P[34] strain, with E9 NSP4 type and mixed I5 + I14 VP6 type, the constellation of genomic segments was rather conserved and were closely related to prototype porcine strains in the four viruses characterized (I5-R1-C1-M1-A8-N1-T7-E1-H1). Most notably, all the viruses displayed a rare NSP3 genotype, T7, which has also been identified in rare human reassortant strains and in the reference strain RVA/Cow-tc/GBR/UK/1973/G6P[5]. This study provides crucial genetic data on these complex viruses and will help understand the origin and ecological niche of gene segments and the role played by pigs in their evolution.     

Isolation of avian paramyxoviruses from sentinel ducks and turkeys in Minnesota

In a 4-year study (1980-1983) involving the use of sentinel ducks that intermingled with wild ducks, a total of 98 paramyxovirus (PMV) isolates (84 Newcastle disease virus, 14 PMV-6) were obtained from 3652 sentinel duck cloacal samples (2.7% isolation rate) collected between June and mid-November each year. PMV infection of sentinel ducks appeared to be seasonal, with the onset of infection occurring between mid-July and mid-August. PMV was not isolated from sentinel turkeys that co-mingled with sentinel ducks during the last 2 years of the study. However, there was serological evidence that the sentinel turkeys were infected with PMV. These findings indicate that wild waterfowl are a natural reservoir of PMV and suggest that interspecies transmission of certain PMV serotypes may occur between waterfowl and turkeys.     

Pathogenesis of rotavirus infection in various age groups of chickens and turkeys: clinical signs and virology

Age-related susceptibility patterns of turkeys, broilers, and specific pathogen-free (SPF) White Leghorn chickens to experimentally induced infection with turkey or chicken rotavirus isolates were compared. The following determinants were evaluated: clinical signs, onset and duration of virus production, viral titers, involvement of intestinal villi in the replication of the virus, and the development of antibodies against the virus. Older turkeys and chickens were more susceptible than were their younger counterparts, turkeys were more susceptible than were broiler and White Leghorn chickens (regardless of age), and broiler chickens were slightly more susceptible than were age-matched White Leghorn chickens. Turkeys developed diarrhea, accompanied by high viral titers within 1 day after inoculation with virus. Viral antigen was found in the epithelial cells of the intestinal villi throughout the intestinal tract and some cells of the cecal tonsils. Antibodies could be detected as early as 4 to 5 days after inoculation. These findings were more pronounced in turkeys inoculated at 112 days of age than in birds inoculated at a younger age. Age-related susceptibility patterns were similar in White Leghorn and broiler chickens. Infection was subclinical in birds less than 56 days old, whereas older birds developed soft feces. Egg production in the White Leghorn chickens decreased after being inoculated with virus at 350 days of age.     

Isolation of five species ofeimeria from chickens in Bangladesh

Five species of Eimeria, namely E. acervulina, E. tenella, E. maxima, E. brunetti and E. necatrix were identified in chickens in Bangladesh on the basis of lesions seen at post-mortem examinations of naturally infected birds, and on the dimensions of oocysts and the lesions seen in chicks experimentally infected with single oocyst derived strains. The use of filter top, polycarbonate cages permitted the isolation of strains without sophisticated animal isolators and is appropriate for use in laboratories throughout the developing world. Responses to a questionnaire sent to all known intensive poultry farms suggested that coccidiosis is a major disease. For control, producers rely mostly on management procedures and the tactical use of sulphonamides; in-feed chemoprophylaxis is not widely used. These control measures are unsatisfactory and recent coccidiosis outbreaks were reported from seven of 16 farms. There was evidence of a seasonal incidence in clinical coccidiosis.     

Pathogenicity of turkey coronavirus in turkeys and chickens

We designed this study to compare the replication potential of turkey coronavirus (TCV) and its effect in chickens and turkeys and to study the effect of singleand combined infection of turkey poults with TCV and astrovirus. We studied the pathogenicity of TCV in experimentally inoculated turkey poults and chickens by observing the dinical signs and gross lesions. Two trials were conducted with 1-day-old and 4-wk-old specific-pathogen-free turkey poults and chickens. One-day-old turkey poults developed diarrhea at 48 hr postinoculation. Poults euthanatized at 3, 5, and 7 days postinoculation had flaccid, pale, and thin-walled intestines with watery contents. The 4-wk-old turkeys had no clinical signs or gross lesions. One-day-old and 4-wk-old chicks developed no clinical signs or gross lesions although the TCV was detected in gut contents of the birds throughout the experimental period (14 days). In another experiment, mean plasma D-xylose concentrations in 3-day-old turkey poults inoculated with TCV, turkey astrovirus, or a combination of both viruses were significantly lower than in the uninoculated controls.