The susceptibility of chicken kidney and oviduct organ cultures to a vaccine strain of avian infectious bronchitis virus.

The minimal infectious dose of the H52 strain of infectious bronchitis virus for organ cultures of oviduct and kidney was compared in chickens of different ages. Organ cultures of oviduct were found to be highly susceptible to infection regardless of the age of chicken and no difference in susceptibility could be demonstrated between cultures of the magnum and uterus regions of the mature oviduct. Kidney organ cultures were less susceptible and resistance to infection increased significantly (P less than 0.001) with the age of the chicken from which cultures were prepared.     

Growth kinetic studies of avian infectious bronchitis virus in tracheal organ cultures.

An egg-adapted vaccine strain (H120) and an organ culture-passaged field strain (HV-10) of avian infectious bronchitis (AIB) virus were propagated in tracheal organ cultures and their growth kinetics examined using nine-day-old embryonated fowl eggs and chick tracheal explants for virus assay. When the H120 strain was assayed in embryonated eggs, titres were approximately log10 2-0 ID50 (50 per cent infectious dose) per ml higher than when assays were performed in tracheal explants. The HV-10 strain, assayed in tracheal explants, yielded higher titres than did the H120 strain, but when assayed in embryonated eggs, yielded only minimal and variable virus titres.     

Gallid-1 herpesvirus infection in the chicken. 3. Reinvestigation of the pathogenesis of infectious laryngotracheitis in acute and early post-acute respiratory disease

Specific-pathogen-free chickens were infected via the trachea when 4 weeks old with 2000 plaque-forming units (PFU) of the virulent Australian infectious laryngotracheitis (ILT) virus strain CSW-1. Titers of ILT virus in the trachea were greatest (10(7.0) PFU/ml in washings, 10(6.0) PFU/g of tissue) 2-4 days postinfection (PI). Infectivity then declined rapidly, to become undetectable by 7 days PI, although highly localized areas of ILT antigen in the tracheal epithelium were occasionally observed by fluorescent antibody staining at 7 and 8 days PI. Tracheal organ cultures established 7 and 8 days PI provided no evidence of latent ILT virus infection at this immediate post-acute stage of pathogenesis. ILT virus was not isolated from peripheral blood leukocytes or lymphoid organs (spleen, bursa, thymus). ILT virus was found in the trigeminal ganglia and/or brain in 14 of 36 chickens (40%) examined between 4 and 7 days after intratracheal inoculation, but it was not in these tissues in five chickens examined at 8 days PI. Virus was also detected at 6 days PI in the trigeminal ganglia in one of five chickens infected by the conjunctival route. These data indicate that the early pathogenesis of ILT (CSW-1) infection frequently involves the tissues of the nervous system. In acute ILT in 4-week-old chickens, interferon-alpha/beta activity was not detectable in serum or tracheal exudates within 14 days PI, but tracheal washings contained significant virus-neutralizing activity by 7 and 8 days PI. In 3-day-old chickens infected via the trachea with 200 PFU of ILT CSW-1, the clearance of ILT virus from the trachea was similar to that observed in 4-week-old chickens, but ILT virus spread systemically to the livers of 20% by 5-7 days PI.     

六株传染性支气管炎病毒的生物学特性鉴定及遗传进化分析

从华南地区疑似传染性支气管炎的病料中,分离到6株传染性支气管炎病毒并对这些分离株进行鸡胚矮小化试验、新城疫病毒干扰试验、血凝特性试验、鸡胚气管环感染试验、S1基因的克隆测序与序列分析。结果表明,各分离株均对鸡胚有明显的致矮小化作用;对新城疫病毒有明显的干扰作用;无直接血凝性,经10g/L胰酶处理后,可凝集鸡的红细胞;对鸡胚气管环有明显的感染致病变作用;利用RT-PCR方法,成功扩增出分离株的S1基因,与参考株S1基因序列比对,其中1株(GD-09II)属于Mass型,剩下5株与LX4型亲缘关系较近。     

The isolation and attenuation of a virus causing rhinotracheitis in turkeys in South Africa

In March 1978, a number of turkeys with severe respiratory symptoms affecting over 80% of the flock were investigated for a possible causative agent. With the standard techniques used for the isolation of bacteriae, mycoplasmae and viruses, only Mycoplasma gallisepticum, Mycoplasma meleagridis and Newcastle disease virus were isolated. Tracheal organ cultures were subsequently prepared from 27-day-old turkey embryos and inoculated with sinus exudate from affected turkeys. After an incubation period of 4 days a virus was isolated with which the typical symptoms, as observed in the field, could be reproduced in susceptible turkeys after 3-5 days. Following primary isolation in tracheal organ cultures, the virus grew readily in embryonated eggs and Vero cells. With the electron microscope, virus-like particles, varying in size from 40 nm-500 nm, were observed, having a pleomorphic shape and studded with fine surface projections. The virus seems to fall into the family Paramyxoviridae. A vaccine produced from attenuated virus in embryonated eggs afforded good protection against mortalities due to airsacculitis that normally follows on to turkey rhinotracheitis infection. The serological and clinical effects of the virus on chickens are also reported on.     

Effects of some components of the humoral immune response on the replication of bovine herpesvirus type I in tracheal organ cultures

The addition of high concentrations of serum neutralizing antibody against bovine herpesvirus type I (BHV-1) to bovine fetal tracheal organ cultures before and after infection with a minimal infectious dose of BHV-1 completely inhibited virus replication. The daily addition of serum antibody from day 0 to day 2 after infection markedly reduced virus yields but failed to cure the infection. The antiviral effect of nasal antibody was not superior to that of an equivalent concentration of serum antibody. Treatment of infected organ cultures with complement sometimes enhanced the antiviral effect of antibody. Peripheral blood lymphocytes from an experimentally infected calf were cultivated in the presence of BHV-1 antigen, and the culture supernatants were shown to possess interferon activity. Pretreatment of organ cultures with this material failed to inhibit BHV-1 replication, but when the interferon treatment was continued daily after infection, there was a transient reduction in BHV-1 replication.     

Comparative use of direct organ cultures of infected chicken tracheas in isolating avian infectious bronchitis virus

Five trials were conducted to compare four in vitro methods of isolating avian infectious bronchitis virus (IBV)-direct organ culture of infected tracheal rings (DOC), inoculation of tracheal organ culture (OC), inoculation of chicken embryo, and inoculation of cultured cells. DOC was prepared from tracheas of chickens experimentally inoculated with field samples. In the other methods, pooled tracheal and kidney suspensions were used to inoculate OC, chicken embryos, and cultured cells. IBV was consistently isolated at the initial passage by the DOC and OC inoculation systems, but it was not always isolated by embryo inoculation and never isolated by cultured-cell inoculation. When combined with immunofluorescent staining, DOC was much more efficient than the OC inoculation system for isolation and identification of the five strains of IBV tested because of its simplicity and speed.     

Recent studies on the enterotropic strain of avian infectious bronchitis virus

Avian infectious bronchitis (AIB) is an economically important disease of chickens. Recent studies have revealed enterotropism by at least one strain of AIB virus with pathological lesions in parts of the gut. This review highlights the findings of the studies so far made on this enterotropic strain of AIB virus.     

Adenovirus infection associated with respiratory disease in commercial chickens

The lesions and etiologic agents associated with 13 outbreaks of respiratory disease in commercial chickens were investigated. Adenoviruses were isolated from tracheal and lung tissues of affected chickens in all 13 outbreaks. Escherichia coli was isolated from the lung of an occasional bird. The tracheal specimens were consistently negative for Bordetella avium, but E. coli and occasionally Staphylococcus aureus were isolated. There was also serological evidence in one outbreak, and pathological evidence in another, of a concurrent infectious bursal disease virus (IBDV) infection of chickens affected with the disease. Gross and microscopic alterations in the tracheas and lungs of affected chickens were similar in all outbreaks and consisted of catarrhal tracheitis and occasionally multifocal pneumonia with mononuclear cell infiltrates. Hepatitis and splenitis with heterophil infiltrates occasionally were seen in birds with coliform septicemia. The tracheal and lung lesions in the present investigation were considered primarily of adenovirus etiology, complicated by secondary bacterial infection.     

Susceptibility of bovine macrophage and tracheal-ring cultures to bovine viruses.

Cultures of macrophages initiated from peripheral blood monocytes and organ cultures of tracheal rings were tested for their susceptibility to bovine viruses. With several notable exceptions, viruses cytopathogenic for bovine embryonic lung cultures were cytopathogenic for macrophages. Although cowpox virus replicated in macrophages, pseudocowpox did not, and although pseudorabies virus replicated within macrophages, infectious bovine rhinotracheitis and DN-599 herpesviruses did not. Bluetongue virus established an interesting relationship with macrophages. Whereas bluetongue virus was initially cytopathogenic for macrophages, it lost its cytopathogenicity on repeated passage, although it was capable of continued replication in macrophages. When subsequently passaged onto bovine embryonic lung cultures, it regained its cytopathogenicity. Parainfluenza-3, bovine viral diarrhea, and infectious bovine rhinotracheitis viruses readily destroyed ciliary activity in tracheal-ring cultures, as contrasted with the inability of bovine respiratory syncytial virus to destroy ciliary activity, even though bovine respiratory syncytial virus was able to replicate within ciliated epithelial cells of tracheal rings.     

Avian infectious bronchitis: cross-protection studies using different Australian subtypes

The cross-immunity of vaccinated chickens after challenge with some Australian infectious bronchitis viruses was assessed by humoral antibody responses and by ciliary activity in tracheal rings of vaccinated chickens following challenge. Four viruses were used for vaccination: Vac 3, Vac 4, both current infectious bronchitis vaccine viruses, and Q1/76 and N2/62. IBV N1/62 (synonym T0 and infectious bronchitis virus N9/74 (synonym Appin) were used to challenge the vaccinated chickens. Results showed a lack of correlation between humoral antibody levels and protection. Cross-immunity was found after vaccination with each subtype, but was lower for Vac 3 and Vac 4 than for Q1/76 and N2/62.     

Effect of lymphocytes and broncho-alveolar washing cells on the replication of bovine herpesvirus type 1 in tracheal organ cultures

The daily addition of lymphocytes collected from a calf between 7 and 11 days after experimental infection with bovine herpesvirus type 1 (BHV-1) to bovine fetal tracheal organ cultures after infection with BHV-1 did not inhibit virus replication. The daily addition of normal lymphocytes, together with a low concentration of serum antibody against BHV-1, had a slight viral inhibitory effect which was believed to be due to antibody-dependent cell-mediated cytotoxicity. The addition of broncho-alveolar washing (BAW) cells, collected before infection or 30 days after infection of a calf with BHV-1, together with lymphocyte culture supernatant, to tracheal organ cultures immediately after infection with BHV-1 produced some inhibition of virus replication. Virus replication was markedly inhibited when BAW cells collected from the calf 18 days after infection were used in a similar manner.     

鸡肾型传染性支气管炎病毒的分离与鉴定

山东省某些大型鸡场自１９９４年以来,连续爆发一种传染快,发病急,死亡率高的呼吸道疫病。剖检出现肾脏病变。从发病鸡场陆续分离到了多个毒株,经过鸡胚传代,新城疫中和,血凝检测,电镜观察,病毒干扰,动物回归,气管环培养等试验确诊所分离的病毒为鸡传染性支气管炎病毒,并对其理化特性进行了研究。     

用SPF鸡制备IBD诊断抗原及血清的研究

将IBDV接种SPF鸡，死者取其法氏囊，经超声波粉碎或匀浆，反复冻融制备IBDAGP诊断原，未死者，再用IBD组织灭活苗免疫制备IBD诊断血清。如此制备的IBD诊断液特异性强、灵敏度高、成本低．适于禽病检验室推广应用。     

Persistence of Mycoplasma gallisepticum in chickens after treatment with enrofloxacin without development of resistance

The ability of the avian pathogen Mycoplasma gallisepticum to persist despite fluoroquinolone treatment was investigated in chickens. Groups of specific pathogen free chickens were experimentally infected with M. gallisepticum and treated with enrofloxacin at increasing concentrations up to the therapeutic dose. When M. gallisepticum could no longer be re-isolated from chickens, birds were stressed by inoculation of infectious bronchitis virus or avian pneumovirus. Although M. gallisepticum could not be cultured from tracheal swabs collected on several consecutive sampling days after the end of the enrofloxacin treatments, the infection was not eradicated. Viral infections reactivated the mycoplasma infection. Mycoplasmas were isolated from tracheal rings cultured for several days, suggesting that M. gallisepticum persisted in the trachea despite the enrofloxacin treatment. The minimal inhibitory concentration (MIC) of enrofloxacin for most of the re-isolated mycoplasmas was the same as that of the strain with which the birds were inoculated. Furthermore, no mutation could be detected in the fluoroquinolone target genes. These results suggest that M. gallisepticum can persist in chickens without development of resistance despite several treatments with enrofloxacin.     

An Alcaligenes faecalis isolate from turkeys: pathogenicity in selected avian and mammalian species

An Alcaligenes faecalis isolate of known pathogenicity for turkeys was examined for adherence and cytotoxicity in tracheal organ cultures of turkeys, chickens, Japanese quail, guinea pigs, hamsters, and mice, and for colonization and pathogenicity in these 6 species. Adherence and colonization were detected by fluorescent antibody staining. Infected and noninfected tracheal rings were examined by phase-contrast microscopy for cytotoxicity (ciliostasis, blebing of the cell membrane, and sloughing of the ciliated epithelium). Alcaligenes faecalis adhered to the tracheal rings of all species examined. Cytotoxicity was apparent in the tracheal rings of turkeys, quail, and chickens. Cytotoxicity was not detected in tracheal rings from the mammalian species. Alcaligenes faecalis colonization of turbinates and tracheas of intact turkeys and quail was detected. Clinical signs of alcaligenes rhinotracheitis were observed and histopathologic characteristics of the disease were detected. Chickens, guinea pigs, hamsters, and mice were refractory to infection with this isolate of A faecalis.     

Virus isolation from tracheal explant cultures and oropharyngeal swabs in attempts to detect persistent Newcastle disease virus infections in chickens

Three-to-seven-week-old broiler-type chickens were inoculated with Newcastle disease virus (NDV) by eye-drop (ED) or intratracheally (IT), and virus isolation was attempted from oropharyngeal (oral) swabs and medium harvested from tracheal explant cultures (TEC). The TEC were maintained in screw-capped tissue-culture flasks for at least 1 month, and medium harvested at regular feeding times was assayed for NDV and NDV antibody. The earliest and latest sample times were 3 and 21 days after NDV inoculation. The three experiments done were: Expt. 1, infection of nonvaccinates with NDV strain La Sota; Expt. 2, infection of NDV vaccinates and nonvaccinates with NDV strain Largo; and Expt. 3, infection of NDV vaccinates and nonvaccinates with NDV wild-type strain Kansas-Manhattan (KM) and two temperature-sensitive (ts) clones derived by J. S. Youngner from the KM strain. All experiments yielded similar results. On day 3 postinoculation (PI), most chickens were shedding virus recoverable by oral swabs and detectable in harvests from TEC prepared on that day. On day 7 PI, there was a sharp reduction in the frequency of virus-positive oral swabs, but there was no decline in the frequency of virus-positive TEC. On day 14 PI or later, all oral swabs and TEC were virus-negative, except for one chicken in Expt. 3 that was oral-swab-positive. There was no evidence of NDV persistence in the TEC of oral-swab-negative chickens on or after day 14 PI. The results of these experiments are in contrast with previous reports of the detection of latent NDV by virus isolation from harvests of TEC prepared 18 or more days PI. The ts clones of strain KM used in Expt. 3 induced a markedly poorer antibody response and were shed for a shorter time than the KM parental virus.     

鸡传染性支气管炎病毒广西分离株血清型的分析

应用病毒感染的鸡胚材料免疫新西兰兔的方法制备抗鸡传染性支气管炎病毒(IBV)单因子血清,然后在鸡胚气管环培养(Tracheal organ cultures,TOC)上对广西分离的7个IBV代表性毒株和3个常用疫苗株进行交叉病毒中和试验。结果显示,10个毒株被分为6个血清型。根据试验所得的R值,应用聚类分析法分析了各血清型毒株之间的亲缘关系,显示目前在广西流行的IBV野毒株之间以及其与疫苗株间的抗原性存在很大程度的差异,分属不同的血清型。同时还对IBV基因分型和血清分型之间的关系进行了探讨。     

Intestinal cryptosporidiosis in chickens

In a retrospective examination of histopathology reports from Aug. 1, 1985, through Sept. 31, 1987, 10 cases of small- or large-intestinal cryptosporidiosis (not epithelial cryptosporidiosis of the bursa of Fabricius) were found in chickens. Infection was evenly distributed among young chickens. Incidence of intestinal cryptosporidiosis increased during 1987. Although all infected birds were clinically ill, signs or gross lesions of intestinal disease were not always present. In all cases, mild to marked histologic lesions were associated with Cryptosporidium sp.; however, intestinal tracts were not cultured for other infectious agents. The numbers of Cryptosporidium sp. and character of inflammatory response were not significantly correlated. A difference (P = 0.01) among intestinal segment (small vs. large) infection with Cryptosporidium was seen. Light-microscopic appearance and organ distribution of Cryptosporidium sp. suggest that in addition to C. baileyi, other Cryptosporidium species infect chickens. Until the diagnostic procedure for outbreaks of gastrointestinal disease in poultry routinely includes histopathology, fecal flotation, and virus, bacteria, and chlamydia cultures, and until species of Cryptosporidium are isolated, identified, reported, and investigated experimentally, the importance of intestinal cryptosporidiosis in chickens will remain unknown.     

Isolation of chicken anaemia virus from broiler chickens.

Chicken anaemia virus (CAV) infection was demonstrated, by both serology and virus isolation, in 1- to 6-week-old broiler chickens originated from various parent flocks in Hungary. Total losses in the broiler flocks were estimated at 7 to 8% and about 25% of the chickens failed to reach target body mass by the 7th week of life. The clinical signs, postmortem lesions and histopathological changes of the affected chickens were similar to those of naturally occurring CAV-induced infectious anaemia of young chickens. In MDCC-MSB1 cell cultures, a chloroform-resistant virus smaller than 50 nm in diameter, resistant to heating at 70 degrees C for 30 min, and antigenically very closely related to the Cux-1 strain of CAV was isolated from the liver of naturally diseased broilers. This virus isolate was designated the Bia strain of CAV. Inoculation of susceptible 1-day-old SPF chicks with a CAV-positive liver extract from naturally diseased broilers caused pathological changes characteristic of CAV infection, namely impaired growth, severe anaemia with atrophy of the bone marrow, marked atrophy of the lymphoid organs and petechial haemorrhages throughout the body. A quite similar pathological syndrome was also induced by inoculation of 1-day-old SPF chicks with the MDCC-MSB1 cell-culture-propagated new Bia strain of CAV. The CAV was successfully reisolated from the livers of experimentally inoculated birds, and antibodies to the reference Cux-1 strain of CAV were also demonstrated by the indirect immunofluorescence test in sera of naturally diseased and experimentally inoculated chickens. No antibodies were found against infectious bursal disease virus, reticuloendotheliosis virus, Marek's disease herpesvirus as well as avian adenoviruses and reoviruses. The reported disease of young broiler chickens was associated with natural infection of a new isolate of CAV. On the basis of its physicochemical, antigenic and pathogenic characteristics, this virus is similar to other strains of CAV isolated from chickens in other countries.