Isolation and characterization of a very virulent Infectious bursal disease virus from turkey

Molecular detection of fowl adenovirus 7 from slaughtered broiler chickens in Iran: the first report

Background

Fowl adenoviruses (FAdVs) are responsible for a variety of clinical symptoms, with an increasing significance in the poultry industry throughout the world. Typical diseases caused by FAdVs include inclusion body hepatitis (IBH), hepatitis-hydropericardium syndrome (HHS), gizzard erosion (GE), respiratory disease, and hemorrhage in muscles and organs.

Aims

During 2020, broiler chickens from the north of Iran showed ecchymotic and petechial hemorrhages in thigh and breast muscles at the slaughterhouse. Hemorrhages were observed in 10% to 60% (with an average of 20-30%) of chicks per flock. To find out the etiology of these lesions, the present study was conducted.

Methods

Different environmental factors were investigated, and FAdV, infectious bursal disease virus (IBDV), and chicken infectious anemia virus (CIAV) were detected using molecular assays.

Results

Among the viruses tested, FAdV was detected by polymerase chain reaction (PCR), and sequence analysis clustered the virus into species E, serotype 7.

Conclusion

This is the first report on FAdV-7 existence among poultry in Iran. Effective screening of the chicks at slaughtering age should be performed from the whole country.

Molecular characterization and pathogenicity of very virulent infectious bursal disease virus isolated from naturally infected turkey poults in Egypt

This study was conducted to investigate the molecular characterization and pathogenicity of very virulent infectious bursal disease virus (vvIBDV) isolated from naturally infected turkey poults and possible spread to chickens. Thirty samples were collected from turkey poults in the vicinity or in the same backyards with chickens suspected to be infected with IBDV and from live bird markets from different localities in Dakahlia governorate, Egypt. There were no obvious clinical signs in tested turkey poults except dehydration and whitish diarrhoea in some birds with no mortality, and post-mortem lesions were observed in few birds as atrophied bursae, nephritis and petechial haemorrhages on thigh muscles. Reverse transcription polymerase chain reaction (RT-PCR), histopathological examination and immunohistochemistry were used for identification of the IBDV. Out of 30 tested samples, 17 samples (56.7%) were positive by RT-PCR. Phylogenetic analysis of VP2 gene of two selected IBDV strains (turkey 1 and turkey 2) showed a close genetic relationship to vvIBDV strains (serotype 1) isolated from chickens in Egypt and other countries with 93.1 to 95.99% identity for turkey 1 strain and 95.54 to 98.51% for turkey 2 strain. Both turkey 1 and turkey 2 strains were closely related to the Nigerian vvIBDV strain isolated from turkeys with 95.78% and 96.37% identity, respectively. Sequence analysis of both strains demonstrated that they have conserved amino acid residues of vvIBDV (I242, I294 and S299) and Y220F amino acid substitution which is very common in Egyptian vvIBDV chicken strains, while Turkey 1 strain has amino acid substitutions at A222P and I256V. Histopathological examination showed marked depletion of bursal lymphoid tissue. In conclusion, for the first time in Egypt, the molecular characterization and pathogenicity confirmed the presence of natural infection of turkey poults with vvIBDV (serotype 1) with possible spread to chickens causing severe economic losses.

Effect of experimental infectious bursal disease virus on clinical signs and pathogenesis of avian influenza virus H9N2 in turkey by real time PCR

Infectious bursal disease virus (IBDV) in turkeys may result in immunosuppression, and inability of turkeys to resist nonpathogenic or less pathogenic organisms. A total number of 120 day-old commercial male turkeys were purchased and blood samples were collected from 20 day-old turkeys, remaining 100 were divided into four equal groups and kept in separated rooms. Groups 1 and 2 were infected with 10⁴ CID₅₀ of IBDV via intra-bursal route on day 1; Groups 1 and 3 were each infected with 10⁶ EID50 of AIV (H₉N₂) via the oculo-nasal routes on day 30. All groups were vaccinated against Newcastle disease vaccine (NDV). Detection of avian influenza virus H₉N₂ in trachea and cloaca swabs and in the tissues, was confirmed by Real-time polymerase chain reaction. Anti- NDV–AIV and anti-IBD titers were measured using HI and ELISA tests, respectively. The present study showed that infectious bursal disease changed the pathogenesis of (AIV) H₉N₂ by affecting AI virus replication and resulted in an increase shedding due to prolonged duration of sever clinical signs. The extent of shedding and virus replication need further study.

Probiotic Lactobacillus and Bifidobacterium strains possess safety characteristics, antiviral activities and host adherence factors revealed by genome mining

Background

Probiotics belonging to Lactobacillus and Bifidobacterium spp. have been exploited for their health benefits in treatment and prevention of many pathological conditions and promoting human health. Recent advances in understanding probiotics-human interaction through microbiome research in the context of various medical conditions suggest their provisional role in preventive, personalized, and predictive medicine. To streamline their application in disease prevention, development of personalized-based treatments, or their use as biomarkers for predictive diagnosis, in vitro screening for strains with potential probiotic properties should be performed. In this work, we aimed to emphasize the probiotic features of four Lactobacillus and two Bifidobacterium probiotic strains which showed antagonistic properties against microbial pathogens.

Methods

Firstly, cytotoxicity assessment of cell-free preparations from these strains was performed using a baby hamster kidney (BHK) cells and cell viability was measured by means of sulfo-rhodamine B stain. Secondly, Newcastle disease (ND) and infectious bursal disease (IBD) viruses which pose a great threat in infected poultry were used for assessing antiviral activity of probiotics. Thirdly, the genomes of six probiotic strains were used to identify genes encoding host adherence factors that mediate interaction with human tissues.

Results

Probiotic preparations exhibited insignificant toxicity as indicated by the high survival rate of BHK cells (surviving fraction varied from 0.82 to 0.99) as compared to the untreated control. Cell-free preparations of probiotics mixed with equal volume of ND and IBD viruses (10⁶ and 10⁴ Tissue Culture Infectious Dose 50, respectively) reduced the titer of ND and IBD viruses on chicken embryo fibroblast cells. Genome mining analysis revealed that the draft genomes of these strains were predicted to encode LPXTG-containing proteins, surface layer proteins, tight adherence pili, sortase-dependent pili, fibronectin, or collagen binding proteins and other factors that adhere to human tissues such as mucus. Such adherence factors enable probiotic bacteria to interact and colonize the host.

Conclusion

Taken together, safety privileges, antiviral activities, and genomically encoded host interaction factors confirmed probiotic features of the six probiotic strains and their potential in promoting human health.

Molecular Characterization of Hemorrhagic Enteritis Viruses (HEV) Detected in HEV-Vaccinated Commercial Turkey Flocks in Germany

Despite the application of live hemorrhagic enteritis virus (HEV) vaccines, HEV field outbreaks are suspected to still occur in turkey flocks in Germany. Increasing secondary bacterial infections in HEV-vaccinated flocks suggest that vaccines may be losing efficacy or, possibly, that vaccine strains are causing disease. Thus, the goal of the current study was to investigate the diversity of HEV isolates from fattening turkey flocks between 2008 and 2012 by characterizing the open reading frame (ORF)1 gene at its 5' and 3' ends. Analyses of ORF1 sequences of field isolates and comparison with sequences present in databases revealed that in many cases (13 out of 16 samples), vaccine (avirulent) strains were present. In addition, data indicated the circulation of suspected virulent field isolates and these isolates (3 out of 16) cluster with an early isolate from Germany in the 1980s, but show some mutations in the predicted amino acid (aa) sequences of ORF1 compared to the early isolate. These virulent isolates clearly differ from the spleen-derived avirulent Domermuth vaccine strain used in Germany. In this study, a unique isolate was identified and showed unusual nucleotide mutations that resulted in aa exchanges at the 5' end of ORF1 between aa positions 34 and 174. This genetic drift suggests evolution of HEV including virulent and vaccine-derived strains in the field. This may lead to evasion of vaccinal immunity by drifted viruses and/or an increase in the virulence of field strains.

Evaluation of infectious bursal disease virus stability at different conditions of temperature and pH

Infectious bursal disease (IBD) is one of the highly pathogenic viral diseases of poultry. The disease poses a serious threat to the economy of many developing countries where agriculture serves as the primary source of national income. Infectious bursal disease virus (IBDV) belongs to the family Birnaviridae. The IBDV is well characterized to cause immunosuppression in poultry. The live attenuated vaccine is the only way to protect the chickens from IBDV infection. The ineffectiveness of vaccine is one of the major causes of IBDV outbreaks in field condition. In the present study, we discuss briefly about the biology of IBDV genome and its proteins under different conditions of temperature and pH in order to evaluate its infectivity under adverse physical conditions. Our results indicate that the IBDV is non-infective above 42 °C and unstable above 72 °C. However, the change in pH does not significantly contribute to the IBDV stability. The study will be useful in estimating an optimum storage condition for IBDV vaccines without causing any deterioration in its viability and effectiveness.

A multiplex RT-PCR assay for detection and differentiation of avian H3, H5, and H9 subtype influenza viruses and Newcastle disease viruses

Avian influenza viruses (AIVs) and Newcastle disease viruses (NDVs) co-circulate in the poultry population in China. These viruses cause repeated disease outbreaks that exhibit similar clinical symptoms and epidemiological patterns. H5 and H9 influenza viruses are the major pathogens infecting poultry stocks. Recently, H3 AIV (one of the main subtypes in waterfowl) has become endemic in chickens. A multiplex reverse-transcriptase polymerase chain reaction (mRT-PCR) assay was designed for simultaneous detection and differentiation of avian H3, H5, H9 subtype AIVs and NDVs. Four primer sets were evaluated, three of which specifically targeted the hemagglutinin genes of H3, H5 and H9 AIVs, while the other targeted the NDV fusion gene. The sensitivity and specificity of the mRT-PCR assay was determined. The assay detected the major clades or genotypes of all of the reference AIVs and NDVs currently circulating in China. In addition, the mRT-PCR results obtained from screening 380 clinical swabs and 12 experimental tracheal samples were consistent with those obtained using conventional virus isolation methods. The mRT-PCR assay was established successfully for the detection and differentiation of avian H3, H5, and H9 subtype AIVs and NDVs. The method should, therefore, provide a valuable diagnostic tool for these infections.