Full genomic characterisation of an emerging infectious laryngotracheitis virus class 7b from Australia linked to a vaccine strain revealed its identity

Sabir, Ahmad Jawad; Olaogun, Olusola Martins; O’Rourke, Denise; Fakhri, Omid; Coppo, Mauricio J. C.; Devlin, Joanne M.; Konsak-Ilievski, Barbara; Noormohammadi, Amir H.

doi:10.1016/j.meegid.2019.104067

Cited by 10 publications

(7 citation statements)

References 34 publications

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“…Outbreaks of ILTV strains were detected in different countries such as in Egypt and Australia which may prompt the vaccine to revert to the virulent form and emergence of new recombinant ILTV strains (4,28), while previous studies have documented severe ILT infections after administration of CEO vaccines (9) that may clarified the severe clinical signs of ILT were reported and confirmed with histopathology, IHC and molecular detection from sampled farms nevertheless their vaccination. However, it could be related to latent infection as Guy et al (12) and Hughes et al (16) documented that latent infection develops where the virus resides in the trigeminal ganglion one week after acute infection.…”

Section: Discussionmentioning

confidence: 78%

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Anatomopathological, ultrastructural, immunohistochemical and molecular characterization of infectious laryngotracheitis outbreaks in poultry farms in Egypt (2018–2020)

El-Saied¹,

El-Mahdy²,

Sakr³

et al. 2021

BJVP

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Infectious laryngotracheitis (ILT) is a severe respiratory disease, which causes high morbidity and mortality in affected birds. In our study, ILT were reported in 42 farms from nine governates over two years (2018–2020) that showed clinical signs of ILT including dyspnea, blood expectoration of, excessive lacrimation, rattling, conjunctivitis. The disease affected different chicken breeds and age groups despite vaccination with licensed and commonly used vaccines. Samples of larynx, trachea, lungs and air sacs were examined and collected for histopathological, ultrastructural, immunohistochemical examination and molecular detection. Gross examination of laryngeal and tracheal lumen revealed different types of exudate varied from catarrhal to fibrinonecotric, also pneumonia and airsacculitis were detected. Histopathological examination showed different alternation in larynx, trachea, lung and air sac as characteristic syncytial cells containing intranuclear inclusion body hanged in fibrinoheterphilic exudate that precent in laryngeal, tracheal, bronchial and parabronchial lumen and air sacs. Tracheal lesion scoring system was used to categorize the severity of lesion in different governates. Tracheal lesion score showed that 6.02%, 26.5%, 43.3% of the birds exhibited mild, moderate, and severe changes, respectively, while 24.18% of the birds exhibited very severe changes. Furthermore, severe cases were related to the Qalyubia , Fayoum then Sharkia Governorate. Moreover, immunohistochemistry was used to detect viral particles in syncytial cells, inflammatory cells beside epithelium of trachea and lung. Transmission electron microscopy enabled the detection of virus particles and demonstrated that heterophils could be infected. PCR targeting a region in the thymidine kinase gene and glycoprotein gJ gene confirmed the presence of infectious laryngotracheitis ILT virus-specific DNA. In conclusion, anatomopathological, immunohistochemical, molecular and ultrastructural findings showed increased of ILTV severity in Egypt. Larynx, trachea, lungs and air sac should be collected and examined that aid in diagnosis. Importance of good biosecurity level to be considered.

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Section: Discussionmentioning

confidence: 78%

“…In Australia, whole genome analysis of an ILTV isolate revealed that recombination is a continuous process, leading to the emergence of virulent strains. The isolate was suggested to be a recombinant of vaccine strain and another recombinant virus (28).…”

Section: Introductionmentioning

confidence: 99%

Anatomopathological, ultrastructural, immunohistochemical and molecular characterization of infectious laryngotracheitis outbreaks in poultry farms in Egypt (2018–2020)

El-Saied¹,

El-Mahdy²,

Sakr³

et al. 2021

BJVP

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“…Very recently, whole genome analysis of an ILTV isolate in Australia revealed that recombination is a continuous process leading to virulent virus. The isolate was suggested to be a recombinant of vaccine strain and another recombinant virus (Sabir et al 2020). To overcome the limitations and biosafety concerns of conventional vaccines, recombinant vaccines such as FPV vector vaccine expressing glycoprotein B and UL32 genes of ILTV(McGeoch et al 2006), two HVT vector vaccines, one containing ILTV glycoproteins I and D, and another containing ILTV glycoprotein B (Esaki et al 2013), LaSota strain of Newcastle diseases virus (NDV) that expresses ILTV glycoproteins (Kanabagatte Basavarajappa et al 2014;Zhao et al 2014), modified very virulent Marek's disease virus (vvMDV) that express ILTV glycoproteins (Gimeno et al 2015) and recombinant vaccines expressing different ILTV glycoproteins including gB, gC, gD, gG, gI, gJ, TK, UL0, UL32, and UL47 (Vagnozzi et al 2012;Yu et al 2017) were introduced and evaluated.…”

Section: Vaccinationmentioning

confidence: 99%

Infectious laryngotracheitis: Etiology, epidemiology, pathobiology, and advances in diagnosis and control – a comprehensive review

Gowthaman

Kumar

Koul

et al. 2020

Veterinary Quarterly

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Infectious laryngotracheitis (ILT) is a highly contagious upper respiratory tract disease of chicken caused by a Gallid herpesvirus 1 (GaHV-1) belonging to the genus Iltovirus, and subfamily Alphaherpesvirinae within Herpesviridae family. The disease is characterized by conjunctivitis, sinusitis, oculo-nasal discharge, respiratory distress, bloody mucus, swollen orbital sinuses, high morbidity, considerable mortality and decreased egg production. It is well established in highly dense poultry producing areas of the world due to characteristic latency and carrier status of the virus. Co-infections with other respiratory pathogens and environmental factors adversely affect the respiratory system and prolong the course of the disease. Latently infected chickens are the primary source of ILT virus (ILTV) outbreaks irrespective of vaccination. Apart from conventional diagnostic methods including isolation and identification of ILTV, serological detection, advanced biotechnological tools such as PCR, quantitative real-time PCR, next generation sequencing, and others are being used in accurate diagnosis and epidemiological studies of ILTV. Vaccination is followed with the use of conventional vaccines including modified live attenuated ILTV vaccines, and advanced recombinant vector vaccines expressing different ILTV glycoproteins, but still these candidates frequently fail to reduce challenge virus shedding. Some herbal components have proved to be beneficial in reducing the severity of the clinical disease. The present review discusses ILT with respect to its current status, virus characteristics, epidemiology, transmission, pathobiology, and advances in diagnosis, vaccination and control strategies to counter this important disease of poultry.

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“…Commonly used ILTV typing techniques such as polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) [ 16 ] and PCR high resolution melt (PCR-HRM) curve analysis [ 6 ] rely on a limited number of genomic fragments that may not represent variations present outside the targeted regions [ 25 ]. Next-generation sequencing (NGS) can provide complete and accurate information about the identity of the ILTV strain involved.…”

mentioning

confidence: 99%

“…Next-generation sequencing (NGS) can provide complete and accurate information about the identity of the ILTV strain involved. Many studies have determined partial or complete genome sequences of vaccine and field strains of ILTV from the USA [ 8 , 27 ], China [ 17 ], and Australia [ 20 , 22 , 25 ] using isolation and propagation of the virus in chicken embryo kidney or fibroblast cells or in embryonated eggs, followed by purification of the virus using gradient centrifugation [ 2 , 17 , 20 , 22 , 26 ]. However, the possibility of genome modifications during the isolation and propagation process cannot be ruled out, and those occasionally may result in the failure of viral growth.…”

mentioning

confidence: 99%

Rapid typing of infectious laryngotracheitis virus directly from tracheal tissues based on next-generation sequencing

et al. 2022

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Infectious laryngotracheitis virus (ILTV) is the causative agent of an economically important disease of chickens causing upper respiratory tract infection. Strains of ILTV are commonly identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and/or PCR high resolution melt (PCR-HRM) curve analysis targeting several genes. However, these techniques examine only a limited number of mutations present inside the target regions and may generate unreliable results when the sample contains more than one strain. Here, we attempted to sequence the whole genome of ILTV with known identity (class 9) directly from tracheal scrapings to circumvent in vitro culturing, which can potentially introduce variations into the genome. Despite the large number of quality reads, mapping was compromised by poor overlapping and gaps, and assembly of the complete genome sequence was not possible. In a map-to-reference alignment, the regions with low coverage were deleted, those with high coverage were concatenated and a genome sequence of 139,465 bp was obtained, which covered 91% of the ILTV genome. Sixteen single-nucleotide polymorphisms (SNPs) were found between the ILTV isolate examined and ILTV class 9 (JN804827). Despite only 91% genome coverage, using sequence analysis and comparison with previously sequenced ILTVs, we were able to classify the isolate as class 9. Therefore, this technique has the potential to replace the current PCR-HRM technique, as it provides detailed information about the ILTV isolates.

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Full genomic characterisation of an emerging infectious laryngotracheitis virus class 7b from Australia linked to a vaccine strain revealed its identity

Cited by 10 publications

References 34 publications

Anatomopathological, ultrastructural, immunohistochemical and molecular characterization of infectious laryngotracheitis outbreaks in poultry farms in Egypt (2018–2020)

Anatomopathological, ultrastructural, immunohistochemical and molecular characterization of infectious laryngotracheitis outbreaks in poultry farms in Egypt (2018–2020)

Infectious laryngotracheitis: Etiology, epidemiology, pathobiology, and advances in diagnosis and control – a comprehensive review

Rapid typing of infectious laryngotracheitis virus directly from tracheal tissues based on next-generation sequencing

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