Effect of methisoprinol on virus replication in cell cultures

The effect of Methisoprinol (active substance: isoprinozine) on the replication of two animal viruses, the TK900 strain of Aujeszky's disease virus and the Roakin strain of the Newcastle disease virus was investigated. When the maximal tolerable doses of the drug were added to two cell cultures (CECC and GMK), its effect on the level of infectious titres of theviruses and their adsorption were assayed. Investigations were also performed to assess the direct effect of Methisoprinol on the viral strains used. The final stage of the experiment aimed at analysing of the replication dynamics of the viruses in the presence of Methisoprinol. Methisoprinol showed no direct effect on the viruses used in the study. Nor did it affect their adsorption. The preparation applied to the culture 24 hours before infection did not influence the replication of viruses, but administered simultaneously with the infection significantly lowered the final titres of viruses. The highest inhibitory effect of the drug was observed during the analysis of the replication dynamics of both viruses in CECC and of pseudorabies virus in GMK cell culture upon the application of the maximal tolerable doses of Methisoprinol and low infectious doses of the viruses.     

Biological properties of Roakin strain of NDV and TK900 strain of ADV after serial passages in CECC in the presence of methisoprinol and KLP-602

Twenty serial passages of the TK900 strain of Aujeszky's disease virus (ADV) and the Roakin strain of Newcastle disease virus (NDV) were made in a chicken embryo cell culture (CECC), in the presence of two antiviral agents: Methisoprinol and KLP-602. The physicochemical properties of passaged viruses were determined. The results obtained suggest that Methisoprinol causes changes in the structure of viral proteins, whereas KLP-602 affects the envelope-dependent properties of the virus. It was also found that the alternations observed in passaged viruses were temporary phenotypic changes only, and not a consequence of permanent transformations of their genotypes.     

Effect of methisoprinol and KLP-602 on virus replication in chicken embryos

The aim of the present study was to examine the effects of two immunomodulators (KLP-602 and Methisoprinol) on the proliferation of two strains of Newcastle disease virus in chick embryos. The effect of the maximum tolerable doses of both drugs (Methisoprinol--6 mg/embryo, KLP-602--5 mg/embryo) on lymphocyte reactivity were determined prior to the experiment. Both drugs inhibited the replication of the Roakin strain of NDV in various experimental designs, but neither of them affected the proliferation of the LaSota strain of NDV.     

Sensitivity and specificity of the fluorescent antibody technique for detection of infectious laryngotracheitis virus.

The specificity of a fluorescent conjugate to infectious laryngotracheitis virus was examined using chick trachea organ culture or tissue sections infected with other avian viruses (adenovirus, infectious bronchitis, poxvirus, reovirus, Newcastle disease virus, Marek's disease virus, avian encephalomyelitis and infectious bursal agent) or Mycoplasma gallisepticum. Confirmation of virus replication in these preparations was obtained by either 1) demonstration of virus titre increase or 2) demonstration of fluorescence when using the homologous conjugate. Once either of these criteria had been satisfied, negative results with the infectious laryngotracheitis conjugate were taken to indicate that the conjugate would not present false positive results in differentiated cells infected with these heterologous viruses. The spectrum of reactivity of the infectious laryngotracheitis conjugate was then examined on organ cultures infected with several infectious laryngotracheitis isolates from across Canada. Finally, the conjugate was applied to experimental and natural cases of infectious laryngotracheitis and its efficiency was compared to routine virus isolation methods.     

Survival of viruses in fermented edible waste material

The survival of selected viruses in fermented edible waste material was studied to determine the feasibility of using this material as a livestock feed ingredient. Seven viruses, including pseudorabies, Newcastle disease, infectious canine hepatitis, avian infectious bronchitis, measles, vesicular stomatitis, and a porcine picornavirus were inoculated into a mixture of ground food waste (collected from a school lung program) containing Lactobacillus acidophilus. Mixtures were incubated at 5 C, 10 C, 20 C, and 30 C for 96 hours. Temperature, pH, and redox potential were monitored. Samples for virus isolation were obtained daily. Newcastle disease virus and infectious canine hepatitis virus survived the entire test period. The porcine picornavirus was inactivated at 30 C after 74 hours, but survived for the entire test period at the other temperatures. Pseudorabies virus was inactivated at 20 C and 30 C within 24 hours, but survived for 48 hours at 10 C and 96 hours at 5 C. Avian infectious bronchitis virus was inactivated at 20 C and 30 C within 24 hours, but survived 72 hours at 5 C and 10 C. Measles and vesicular stomatitis viruses were rapidly inactivated at all 4 temperatures.     

INTERACTION BETWEEN INFECTIOUS BURSAL DISEASE VIRUS AND NEWCASTLE DISEASE VIRUS IN CHICKENS

The Australian strain of infectious bursal disease virus (IBDV), 002/73, affected the response of chickens to Newcastle disease virus (NDV). The titre of serum antibodies to NDV in chickens infected with IBDV was significantly lower than that of birds infected with NDV alone. It also appeared that IBDV affected NDV excretion from chickens as NDV was more frequently isolated from chickens infected with IBDV, IBDV infection did not alter the pathogenicity of NDV in chickens. This Australian strain of IBDV therefore appeared to be immunodepressive in one-day-old chickens.     

Modification of three avian viruses passaged in Chinese hamster lung cells (Don) in pathogenicity to chicken embryo

The Beaudette 42 strain of avian infectious bronchitis virus, Sato strain of Newcastle disease virus, and Uchida strain of avian reovirus were passaged in Chinese hamster lung cells (Don), and some properties were examined. The Don-passaged strains showed a difference in replication in Don and chicken embryo kidney cells in one-step growth curve examinations and a partial modification in pathogenicity to chicken embryos; nevertheless, neutralization tests revealed no serological alteration.     

A serological and virological survey for evidence of infection with Newcastle disease virus in Australian chicken farms

OBJECTIVE: To determine the prevalence and distribution of antibodies to Newcastle disease virus on Australian chicken farms and to determine the pathotype and relationships of the Newcastle disease viruses present on those farms. DESIGN: A cross-sectional survey of 753 commercial chicken farms. PROCEDURE: The survey comprised a detailed questionnaire and collection of venous blood samples. The titre of antibodies to Newcastle disease virus was determined by haemagglutination inhibition. Virus isolation was conducted from cloacal and tracheal swabs taken from chickens in serologically positive flocks. Virus isolates were pathotyped on the basis of the deduced Fusion protein cleavage site determined by nucleotide sequencing of a 265 bp region of the genome in the region of the cleavage site. RESULTS: Antibody evidence of Newcastle disease virus infection was found on 300 of the 753 surveyed farms throughout all 11 geographic regions of the survey. The highest prevalence occurred in the Sydney basin, New South Wales and Victoria east regions. Antibody titres were also highest in the regions where serologically positive flocks were most prevalent. The 259 virus isolates revealed nine different RNA sequences. Of the nine virus groups isolated, the most common group W was identical in sequence to the V4 vaccine strain. Five of the other groups had novel RNA sequences in the region of the F protein cleavage site. CONCLUSIONS: Antibodies to Newcastle disease virus are highly prevalent in the Australian chicken flock but all identified strains were avirulent in nature.     

In ovo vaccination of specific-pathogen-free chickens with vaccines containing multiple agents.

We used in ovo technology to protect chickens against multiple diseases by inoculating vaccines containing mixtures of live viral agents. A single in ovo injection of a vaccine containing serotypes 1, 2, and 3 of Marek's disease virus (MDV), a vaccine strain of serotype 1 infectious bursal disease virus (IBDV), and recombinant fowl pox vaccine with HN and F genes of Newcastle disease virus (rFP-NDV) induced protection against virulent MDV, IBDV, Newcastle disease virus, and fowl poxvirus. The multiple-agent vaccine induced specific antibodies against the viral agents present in the mixture and did not adversely affect the survival of hatched chickens. Inoculation of a vaccine containing serotypes 1, 2, and 3 of MDV and IBDV did not affect hatchability of eggs, although the addition of rFP-NDV to the mixture reduced hatchability by 23%-26%. In ovo vaccination with a vaccine containing MDV and IBDV vaccine viruses did not exacerbate the inhibitory effect of individual viral agents on humoral and cellular immune competence.     

鸡新城疫Lasota—传染性支气管炎W93二联活疫苗研制

鸡新城疫（ＮＤ）Ｌａｓｏｔａ和肾变病型传染性支气管炎（ＮＩＢ）Ｗ９３弱毒经１０日龄ＳＰＦ鸡胚同胚培养,收获含毒鸡胚液,制成Ｌａｓｏｔａ－Ｗ９３二联活疫苗。经实验室检测和临床应用证明,用于预防ＮＤ和ＮＩＢ效果好。     

THE ISOLATION OF LENTOGENIC STRAINS OF NEWCASTLE DISEASE VIRUS IN AUSTRALIA

SUMMARY Twelve isolations of Newcastle disease virus were made from 77 clinical samples from chickens with conjunctivitis, respiratory disease, proventriculitis and bursal atrophy. Nine of the Isolations were made from chickens with conjunctivitis. The viruses were identified as Newcastle disease virus by inhibition of their haemagglutinins with specific antiserum to Newcastle disease virus. The viruses failed to kill chicken embryos after inoculation into the allantoic cavity and they were judged to be lentogenic strains. There was no evidence that the Newcastle disease viruses were responsible for any of the clinical conditions from which they were isolated. The presence of other agents in 10 of the samples was indicated by reduced production of haemagglutinin in allantoic fluids of infected embryos, by deaths of infected embryos, by the production of cytopathic changes in avian cell cultures and by electron microscopy. Three isolations of infectious bronchitis virus, 2 of avian adenovirus and one of avian reovirus were made. Other samples were suspected of containing infectious bronchitis virus and mycoplasmas, but these were not isolated. The Newcastle disease viruses failed to produce plaques in chicken embryo fibroblast cell cultures and they were separated from the contaminating agents by haemagglutination and elution followed by passage at terminal dilution in chick embryos. No Newcastle disease virus was isolated from 60 caecal tonsils and 60 lung samples from 9-week-old broiler chickens. Eight lung samples yielded mycoplasmas that caused haemadsorption in chicken cell cultures. The mycoplasmas were probably Mycoplasma gallisepticum.     

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.     

Inactivated oil emulsion vaccines from selected clones of Newcastle disease virus

The immunogenicity of oil emulsion (OE) vaccines prepared from two selected clones of a Nigerian strain of Newcastle disease virus and two commercial vaccine strains were compared. Geometric mean haemagglutination inhibition titre was lowest in OE-Lasota, although all four vaccines gave 100% protection against clinical Newcastle disease. The use of OE vaccines is recommended for commercial use in Nigeria.     

不同来源鸡传染性法氏囊病疫苗的免疫效果观察

为了研究商品蛋雏鸡传染性法氏囊病疫苗的免疫程序,对MB株活疫苗、G606株活疫苗和B38株活疫苗3株传染性法氏囊病活疫苗进行了疫苗毒力、免疫效果及对新城疫疫苗免疫影响的观察。结果表明,MB株活疫苗毒力最强,G606株活疫苗次之,B38株活疫苗毒力最弱;突破母源抗体能力强弱依次为MB株活疫苗、G606株活疫苗、B38株活疫苗,其中B38株活疫苗产生的抗体滴度最高,MB株活疫苗次之,G606株活疫苗最低;MB株活疫苗可降低新城疫疫苗产生的血凝抑制抗体滴度,G606株活疫苗和B38株活疫苗对此无影响。     

Pathological and immunological study of an in ovo complex vaccine against infectious bursal disease

The appearance of very virulent strains of infectious bursal disease (IBD) virus at the end of the 1980s made it necessary to develop more effective immunization procedures. To facilitate this, the immunogenicity and the immunosuppressive effect of a mild (G-87), an intermediate (LIBD) and an intermediate-plus (IBDV 2512) IBDV strain were tested after the in ovo inoculation of 18-day-old SPF and broiler chicken embryos. It was established that no noteworthy difference existed between the immunized and the control embryos in hatching rate and hatching weight. The higher the virulence of the vaccine virus strain, the more severe damage it caused to the lymphocytes of the bursa of Fabricius. In SPF chickens, the haemagglutination inhibition (HI) titres induced by a Newcastle disease (ND) vaccine administered at day old decreased in inverse ratio to the virulence of the IBD vaccine strain, while in broiler chickens this was not observed. Despite the decrease of the HI titre, the level of protection did not decline, or did so only after the use of the 'hot' strain. SPF chickens immunized in ovo with a complex vaccine prepared from strain IBDV 2512 and IBD antibody showed the same protection against Newcastle disease as the broilers. In broiler chicken embryos immunized in ovo, only strain IBDV 2512 induced antibody production, and such chickens were protected against IBD at 3 weeks of age. The complex vaccine administered in ovo has been used successfully at farm hatcheries as well.     

The propagation of avian viruses in a continuous cell line (QT35) of Japanese quail origin

Seven of nine avian virus families tested (Birnaviridae, Coronaviridae, Herpesviridae, Paramyxoviridae, Poxviridae, Reoviridae, and Retroviridae) were found to replicate in a quail fibroblast cell line, designated QT35, resulting in a cytopathic effect (CPE) visible with the naked eye or by low-power microscopy. In comparison, only one (Paramyxoviridae) of seven mammalian virus families tested produced an observable CPE. Cytopathic changes induced by examined viruses were round cell, syncytial, and focus formation. Trypsin did not promote cytopathic changes by selected CPE-negative avian and mammalian viruses in QT35 cells. Several avian viruses (infectious bursal disease virus, Newcastle disease virus, Canary pox virus, and reovirus) formed plaques under agar. Avian reovirus and infectious bursal disease virus produced similar titers in chicken embryo fibroblast (CEF) and QT35 cell cultures. Chicken-egg-yolk neutralizing-antibody titers to IBDV were comparable in CEF and QT35 cell-culture systems.     

Effects of standard and variant strains of infectious bursal disease virus on infections of chickens

T-cell-mediated and humoral immune responses were measured in chickens infected with standard and variant strains of infectious bursal disease virus. One-day-old and 3-week-old chickens were infected with these viruses and then given sheep RBC, killed Brucella abortus strain 19, and Newcastle disease virus. Appropriate serologic tests were used to monitor the primary and secondary responses to the antigens. Lymphoblast transformation assays were performed weekly. The response to the infectious bursal disease virus was determined by virus neutralization tests, microscopic examination of bursas, and bursal to body weight ratios. One-day-old chickens had T-cell-mediated and humoral immune suppression with both strains of virus, compared with controls. The lymphoblast transformation responses indicated that the variant strain was significantly (P less than 0.05) more suppressive than the standard strain. Three-week-old chickens had humoral immune suppression with the standard strain, but not with the variant strain. The lymphoblast transformation response was transiently suppressed at this age by the variant strain only. During the first week of infection, 1-day-old and 3-week-old chickens had lower neutralizing antibody titers to the variant strain than to the standard strain.     

The sensitivity of some avian viruses to formaldehyde fumigation.

Various avian viruses (infectious bursal agent, reovirus, adenovirus, infectious bronchitis, Newcastle disease, poxvirus, avian encephalomyelitis and infectious laryngotracheitis virus) as suspensions in buffer or in a litter slurry were exposed to aerosolized formalin in an attempt to determine the efficacy of this fumigation method for decontamination of laboratory isolation cubicles. Formalin (37% formaldehyde) was delivered by a commercial insecticide fogger at a flow rate of 40 ml per minute and a volume of 36 ml per cubic meter of space. Fumigated cubicles were left sealed for 18 hr (cycle 1) before viruses were sampled, or were then exposed to a second fumigation and left sealed for an additional six hour period (cycle 2) before viruses were titrated (commencing at a 1:10 dilution) for residual infectivity. Although the infectivity of all viruses was reduced by over 99% by one fumigation cycle, the second cycle was necessary for reduction of Newcastle disease and reoviruses to non-detectable (no infectivity demonstrated in a 1:10 dilution of fumigated virus) levels.     

Virus interference between H7N2 low pathogenic avian influenza virus and lentogenic Newcastle disease virus in experimental co-infections in chickens and turkeys

Low pathogenicity avian influenza virus (LPAIV) and lentogenic Newcastle disease virus (lNDV) are commonly reported causes of respiratory disease in poultry worldwide with similar clinical and pathobiological presentation. Co-infections do occur but are not easily detected, and the impact of co-infections on pathobiology is unknown. In this study chickens and turkeys were infected with a lNDV vaccine strain (LaSota) and a H7N2 LPAIV (A/turkey/VA/SEP-67/2002) simultaneously or sequentially three days apart. No clinical signs were observed in chickens co-infected with the lNDV and LPAIV or in chickens infected with the viruses individually. However, the pattern of virus shed was different with co-infected chickens, which excreted lower titers of lNDV and LPAIV at 2 and 3 days post inoculation (dpi) and higher titers at subsequent time points. All turkeys inoculated with the LPAIV, whether or not they were exposed to lNDV, presented mild clinical signs. Co-infection effects were more pronounced in turkeys than in chickens with reduction in the number of birds shedding virus and in virus titers, especially when LPAIV was followed by lNDV. In conclusion, co-infection of chickens or turkeys with lNDV and LPAIV affected the replication dynamics of these viruses but did not affect clinical signs. The effect on virus replication was different depending on the species and on the time of infection. These results suggest that infection with a heterologous virus may result in temporary competition for cell receptors or competent cells for replication, most likely interferon-mediated, which decreases with time.     

Inactivated oil emulsion vaccines from selected clones of Newcastle disease virus

Summary

The immunogenicity of oil emulsion (OE) vaccines prepared from two selected clones of a Nigerian strain of Newcastle disease virus and two commercial vaccine strains were compared. Geometric mean haemagglutination inhibition titre was lowest in OE‐Lasota, although all four vaccines gave 100% protection against clinical Newcastle disease. The use of OE vaccines is recommended for commercial use in Nigeria.