First detection and molecular characterization of avian polyomavirus in young parrots in Pakistan

Veterinary Research Communications - Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause...     

Papovavirus infection in hand-fed parrots: virus isolation and pathology

Papovavirus infection was diagnosed in 44 parrots of at least 18 species exclusive of the budgerigar (Melopsittacus undulatus). The birds were 14 days to 4 months old and had been removed from parental care and hand-fed as nestlings. The birds had been unexpectedly found dead after having evidenced no premonitory signs of illness, or they died following a short (12-to-48-hour) period of lassitude and anorexia. In most cases, necropsies revealed pallor, multiple hemorrhages, splenomegaly, and hepatomegaly with multifocal necrosis. Histological lesions included multifocal to diffuse hepatic necrosis that spared the periportal hepatocytes, karyomegaly of splenic reticuloendothelial cells and cells in other tissues, membranous glomerulopathy, and necrosis of bursal medullary lymphocytes. Papovaviruses were isolated from two cases, and papovavirus infection was confirmed in 27 of the birds by the fluorescent-antibody test using a conjugate against a papovavirus isolated from a budgerigar.     

An outbreak of the polyomavirus infection in budgerigars and cockatiels in Slovakia, including a genome analysis of an avian polyomavirus isolate

In winter 2003-04, large numbers of budgerigars (Mellopsitacus undulatus) and cockatiels (Nymphicus hollandicus) fell ill and died in a large parrot-breeding aviary in Slovakia. In budgerigars, the disease outbreak occurred at the age of 2-3 weeks; cockatiels died within their first 7 days of life. In budgerigars, symptoms of the disease included delayed growth, tremor, darkish discoloration of skin, quill bleeding, and feathering defects. cockatiels often died without any symptoms and with a full crop; feathering defects occurred sporadically. Electron microscopy with negative staining of aqueous lysates of the affected skin and of bleeding quills showed isolated or clustered polyomavirus particles 45-50 nm in size. Long filamentous forms of the virus were also found in virion clusters of skin lysates from the budgerigars. In ultrathin sections through the pathologically altered skin tissue of budgerigars, virus particles were present in both nuclei and cytoplasm of epidermal cells, often in crystalline form. In infected cells, enlarged nuclei showed an extensive chromatin margination. On the DNA level, presence of a polyomavirus infection was conclusively proved by the polymerase chain reaction using avian polyomavirus (APV)-specific primers. A sequence analysis of the gene encoding viral protein (VP)1 and of the combined region for VP2 and VP3 proteins revealed a previously undescribed synonymous mutation in this isolate. This report extended the knowledge of the area of APV occurrence and of the spectrum of hosts in the context of genomic and morphologic variability of APV isolates.     

禽白血病病毒自然感染及抗体变化动态规律

试验随机选取1日龄地方鸡(原种鸡)115只,带翅号。于1、7、14、21、28、38、58、68、88、98、108、120、130、140、150、160、170、180、190、200、210、220、260、300日龄按号对应采泄殖腔棉拭子进行ELISA检测禽白血病病毒p27抗原。同时按号对应翅静脉采血分离血清进行ELISA检测A、B亚型抗体和J亚型抗体。260日龄时,对全群鸡只进行病毒分离。试验结果表明,全群鸡在监测的300日龄内均有ALV感染发生。其中p27抗原检出率在7日龄时达到最低值,为2.11%;在170日龄时达到最高峰,为32.18%。从38日龄到300日龄逐渐出现ALVA、B抗体阳性鸡只,阳性率在10%左右。260日龄时阳性率达到最高峰,为30.86%。260日龄病毒分离阳性率为29.49%(23/78),略高于棉拭子p27检出率20%(16/80),二者符合率为79.49%。J亚群抗体检测均为阴性。病毒感染与抗体变化没有直接相关性。     

Evaluation of antibody response to vaccination against West Nile virus in thick billed parrots (Rhynchopsitta pachyrhyncha)

West Nile virus (WNV) was first documented in North America in New York City in 1999. Several deaths attributable to WNV have been reported in captive thick-billed parrots (Rhynchopsitta pachyrhyncha), an endangered psittacine native to North America. The serologic responses in 12 captive adult thick-billed parrots after a series of three initial WNV vaccine injections with annual boosters over 6 yr was evaluated. In addition, the serologic responses of 11 thick-billed parrot chicks following an initial vaccination series to determine if there were seroconversions were also reported. Most adults (67%) had seroconverted after 5 yr of annual vaccination, with a median titer of 1:80 (range 1:40-1:160) for those that seroconverted. After the first year, birds were likely naturally exposed to WNV, which limited interpretation of titers. None of the chicks seroconverted during the initial three-vaccine series; only two of four chicks (50%) had seroconverted when tested at the 1-yr yearly booster, and at 2 yr, three of four chicks had seroconverted. Although some birds had detectable antibody titers, it is unclear whether this vaccine can reliably provide protection against WNV in thick-billed parrots.     

Detection of avian polyomavirus infection by polymerase chain reaction using formalin-fixed, paraffin-embedded tissues

Avian polyomavirus infection in psittacines was diagnosed in tissues by the use of polymerase chain reaction (PCR) test. The tissues used in the procedure were either formalin-fixed tissues embedded in paraffin blocks or fresh tissues (heart, liver, and spleen) collected from the psittacines during necropsy. DNA was extracted from these tissues and was tested with the published primers for avian polyomavirus VP1 gene in the PCR that yielded an amplicon of 550 base pair size, which was then visualized by electrophoresis. The amplicon size was consistent with avian polyomavirus. The PCR test was found to be an effective method for identifying avian polyomavirus infection in both formalin-fixed, paraffin-embedded and fresh tissues from psittacine birds of different age groups.     

Temporal development of bluetongue virus protein-specific antibody in sheep following natural infection

Humoral immune responses of sheep to natural bluetongue virus (BTV) infection were studied on a temporal basis. The temporal development of viral protein-specific IgG was determined by western immunoblotting; virus neutralization and agar gel immunodiffusion (AGID) were conducted for comparative purposes. Prior to the emergence of the arthropod vector and the associated transmission of BTV, virus-neutralizing antibody was absent from all sentinel sheep; 3 sheep had pre-existing AGID antibody and all sheep had IgG, specific for 4 viral proteins, as determined by immunoblotting. Following emergence of the BTV vector, 9 of 11 sheep became infected, as determined by virus isolation, with BTV. All sheep developed virus-neutralizing and AGID antibody. However, only those sheep with a demonstrable viremia experienced an increase in viral protein-specific antibody. Development of viral protein-specific IgG varied with the individual animal and no obvious correlation between a specific response and protective immunity or viral clearance was noted. From a diagnostic viewpoint, the immunoblotting procedure was superior in identifying past exposure to BTV, as compared with neutralization and AGID. In addition, the application of immunoblotting to paired serum samples appeared to be a sensitive indicator of viremia.     

Egg transmission of avian adenovirus-associated virus and CELO virus during a naturally occurring infection.

Both avian adenovirus-associated virus (A-AV) and CELO virus were isolated from the embryonating eggs of 25-week-old black sex-linked hens during a naturally occurring infection. In the first 7 days of egg collection, A-AV was isolated from 10 of 43 (23.2%) embryonating eggs, and CELO virus was isolated from 8 of 43 (18.6%) embryonating eggs. Both viruses were isolated from six eggs. In the next 16 days of egg collection, A-AV and CELO virus were coisolated from 1 of 127 (0.8%) eggs; all other samples were negative for both viruses. All six hens transmitting A-AV to eggs and 5 of 6 hens transmitting CELO virus showed seroconversions (fourfold increase in antibody concentrations). Viruses were not isolated from eggs after the hens showed a fourfold increase in antibody concentrations.     

Breda virus (Toroviridae) infection and systemic antibody response in sentinel calves

Enzyme-linked immunosorbent assays were established to detect Breda virus antigen in feces and homologous antibodies of the IgG1, IgM, and IgA isotypes in serum. With the aid of solid-phase immune-electron microscopy, torovirions in fecal material were observed. The course of natural infection was studied in 10 sentinel calves that had been obtained from different farms, and housed together at 1 week of age. They were separated from other cattle until the age of 10 months. Up to the age of 4 months, all calves regularly excreted Breda virus in the feces. Irrespective of the existence of IgG1 isotype maternal antibodies, all calves had early IgM responses in serum, but lack of IgA seroconversion. In 7 calves, antibody titer decreased below detection, whereas 3 calves had an isotype switch, resulting in persistent IgG1 titer. After introduction into the dairy herd at 10 months of age, all calves had diarrhea, and shedding of Breda virus was observed in 8 of them. Seroconversion for all antibody isotypes was observed, indicating lack of mucosal memory. In contrast, coronavirus infection in the presence of maternal antibodies led to isotype switch in all calves but one, and a memory response was observed after introduction into the dairy herd.     

Influence of strain, dose of virus, and age at inoculation on subgroup J avian leukosis virus persistence, antibody response, and oncogenicity in commercial meat-type chickens

The effects of viral strain, viral dose, and age of bird at inoculation on subgroup J avian leukosis virus (ALV J) persistence, neutralizing antibody (VNAb) response, and tumors were studied in commercial meat-type chickens. Chickens were inoculated on the fifth day of embryonation (5 ED) or on day of hatch (DOH) with either 100 or 10,000 50% tissue-culture infective dose (TCID50) of one of three ALV J strains, namely ADOL Hcl, ADOL 6803, or ADOL 4817. At 1, 3, 7, 11, 15, 19, 23, 27, and 32 wk posthatch, chickens were examined for ALV J viremia and VNAb against the inoculated strain of ALV J. A high incidence (83%-100%) of ALV J persistence was observed in all treatment groups. Development of VNAb did not always lead to viremia-free status; even though 18% of the chickens developed VNAb, only 4% were able to clear viremia. The viral strain, dose, and age of bird at inoculation seemed to have an effect on the incidence of VNAb; however, the differences were statistically significant in only some treatment groups. Chickens infected with ADOL 6803 had higher incidence of VNAb than chickens infected with ADOL Hc1 and ADOL 4817 (P < 0.05 in groups 5 ED at 100 TCID50 and DOH at 10,000 TCID50). There was a trend in all groups inoculated with 100 TCID50 to have higher incidence of VNAb than that of groups inoculated with 10,000 TCID50 (ADOL 6803 at 5 ED and ADOL 4817 at DOH [P < 0.05]; ADOL Hc1 at DOH [P < 0.08]). In most treatment groups (ADOL Hc1 at 100 and 10,000 TCID50, ADOL 6803 at 10,000 TCID50, and ADOL 4817 at 100 TCID50), chickens inoculated at DOH had higher incidence of VNAb than that of chickens inoculated at 5 ED (ADOL 6803 at 10,000 TCID50 [P < 0.05], ADOL Hc1 at 100 TCID50 [P < 0.08]). Incidence of ALV J-induced tumors and tumor spectrum were influenced by viral strain, age at inoculation, and VNAb response.     

Local antibody response in avian infectious bronchitis: virus-neutralizing antibody in tracheobronchial secretions

Specific-pathogen-free chickens were tested for local antibody response after respiratory exposure to live avian infectious bronchitis virus (IBV). Tracheobronchial secretions were obtained after intraocular-intratracheal vaccinations with Holland and Massachusetts 41 strains IBV. Low levels of immunoglobulin (Ig)A and IgG virus-neutralizing antibodies were detected in secretions after each of two vaccinations with a moderate dose (10(4) EID50), neutralizing activity in secretions was found mainly in IgG antibody. Only challenge exposure to Holland IBV resulted in a marked secondary secretion antibody response.     

Seroprevalence of avian influenza virus, infectious bronchitis virus, reovirus, avian pneumovirus, infectious laryngotracheitis virus, and avian leukosis virus in Nigerian poultry

Eight poultry farms in Nigeria, including chickens from nine breeder, 14 broiler, 28 pullet, 11 layer, and three cockerel flocks, were tested for antibody seroprevalence to the following poultry viruses of potential economic importance: infectious bronchitis virus (IBV), avian reovirus, avian pneumovirus (APV), infectious laryngotracheitis virus (ILTV), avian influenza virus (AIV), and avian leukosis virus (ALV). Serum samples were collected between 1999 and 2004 and were tested for antibodies using commercial enzyme-linked immunosorbent assay (ELISA) kits. Seroprevalence was very high for IBV (84%); intermediate for reovirus (41%), APV (40%), and ILTV (20%); and very low for ALV (<5%) antibodies. By commercial ELISA, the seroprevalence of antibodies against AIV was, in some flocks, up to 63%. However, more specific assays did not confirm AIV antibodies, indicating that all flocks tested were free of avian influenza antibodies. Birds seemed to be first infected by IBV (at about 7 wk of age), then by reovirus at 12 wk, before they became infected by APV (week 25) and ILTV (week 30). This is the first report of serological evidence of the above viruses in West Africa. Further studies are necessary to assess economic losses due to these avian viruses and the costs and benefits of countermeasures.     

Humoral antibody response and assessment of protection following primary vaccination of chicks with maternally derived antibody against avian infectious bronchitis virus

Commercially bred chicks with maternally derived antibody to avian infectious bronchitis virus (IBV) were hatched in isolated conditions and a number vaccinated within the first three weeks of life with live IBV strain H120. Humoral antibody responses were assayed by haemagglutination inhibition (HI) or neutralisation (SN) tests, and the degree of protection against challenge with the virulent Massachusetts M41 strain assessed on the basis of tracheal ciliary activity four days after challenge. Maternal antibody in unvaccinated chicks declined linearly with a mean half-life of five to six days based on both HI and SN tests; these chicks were protected against challenge until four weeks old. There was complete correlation between ciliary activity and histopathological findings, but little between protection and antibody titre. It was concluded that the optimum age for primary vaccination was about two weeks.     

A survey of avian polyomavirus (APV) infection in imported and domestic bred psittacine birds in Japan

Although birds infected with avian polyomavirus (APV) subclinically could be a source of infection, no epidemiological studies of APV in psittacine birds have been reported in Japan. In the present study, we investigated subclinical morbidity rate of APV in imported and domestically bred psittacine birds by polymerase chain reaction (PCR). Of 402 live birds from which blood or feather samples were taken between April, 2003 and March, 2004, 11 (2.7%) were found to be APV positive. The DNA sequences of the APV t/T antigen region were determined for five APV-positive randomly selected samples and were found to be conserved.     

H9N2亚型禽流感病毒感染TC-1细胞诱导的免疫反应

为了更好地了解宿主对禽流感病毒(AIV)感染后的免疫反应,本试验以TC-1细胞为模型,感染H9N2亚型AIV。通过荧光定量PCR(qRT-PCR)和酶联免疫吸附试验(ELISA)方法检测了3种模式识别受体(TLR-3、RIG-I和MDA-5)和5种炎性细胞因子(IL-6、RANTES、IP-10、TNF-α和IFN-β)。结果显示:3种模式识别受体中MDA-5上调最为明显,5种炎性因子中RANTES和IP-10上调最为明显;而IL-6、TNF-α和IFN-β上调相对较平缓。本研究结果表明:在病毒感染过程中MDA-5反应较TLR-3和RIG-I更为强烈,而在炎性反应过程中RANTES和IP-10反应更加剧烈,IL-6、TNF-α和IFN-β反应则相对较温和一些。本研究在一定程度上反映了机体对流感病毒的免疫反应机制,为在生产中疫苗的使用具有一定的指导意义。     

重组禽流感病毒H5亚型二价灭活疫苗(H5N1,Re-5+Re-4)免疫鸡和鸭后抗体消长规律

禽流感(AI)是由A型流感病毒引起的一种禽类传染病.根据致病性的不同将禽流感分为高致病性禽流感(HPAI)和低致病性禽流感(IPAI),HPAI被世界动物卫生组织(OIE)列为A类传染病,我国将其列为一类动物疫病 [1].近几年来,禽流感在世界各地反复出现,2004年亚洲发生了高致病性禽流感,2006年底和2007年初东南亚又出现疫情,并发现了人感染禽流感.我国养禽业也一直受到禽流感的威胁.因此,它不仅给畜牧业造成了巨大的损失,而且给人们的公共卫生安全带来了严重的威胁.     

Immune response to avian leukosis virus infection in chickens: Sequential expression of serum immunoglobulins and viral antibodies

Chickens of a 15I₅ × 7₂ cross that produces endogenous Rous associated virus (RAV-0) were infected with subgroup A lymphoid leukosis virus (RAV-1). Within 3 weeks, before RAV-1 neutralizing antibodies were detected, significantly higher levels of serum immunoglobulin G (IgG) were found in infected birds than in uninoculated hatchmates. Immunoglobulin M was significantly elevated only during the late leukotic state. Although most of the inoculated birds tested had RAV-1 neutralizing antibodies, no correlation was found between IgG levels and antibody titers. Tolerance to endogenous virus (RAV-0) and viral group-specific antigen was apparently abrogated by RAV-1 inoculation because significantly higher percentages of iodinated envelope glycoprotein (gpE) of RAV-0 and a viral structural antigen of mol. wt 19,000 daltons (p 19) were precipitated by sera from inoculated birds than from control birds.