Evaluation of Recombinant Herpesvirus of Turkey Laryngotracheitis (rHVT-LT) Vaccine against Genotype VI Canadian Wild-Type Infectious Laryngotracheitis Virus (ILTV) Infection

In Alberta, infectious laryngotracheitis virus (ILTV) infection is endemic in backyard poultry flocks; however, outbreaks are only sporadically observed in commercial flocks. In addition to ILTV vaccine revertant strains, wild-type strains are among the most common causes of infectious laryngotracheitis (ILT). Given the surge in live attenuated vaccine-related outbreaks, the goal of this study was to assess the efficacy of a recombinant herpesvirus of turkey (rHVT-LT) vaccine against a genotype VI Canadian wild-type ILTV infection. One-day-old specific pathogen-free (SPF) White Leghorn chickens were vaccinated with the rHVT-LT vaccine or mock vaccinated. At three weeks of age, half of the vaccinated and the mock-vaccinated animals were challenged. Throughout the experiment, weights were recorded, and feather tips, cloacal and oropharyngeal swabs were collected for ILTV genome quantification. Blood was collected to isolate peripheral blood mononuclear cells (PBMC) and quantify CD4+ and CD8+ T cells. At 14 dpi, the chickens were euthanized, and respiratory tissues were collected to quantify genome loads and histological examination. Results showed that the vaccine failed to decrease the clinical signs at 6 days post-infection. However, it was able to significantly reduce ILTV shedding through the oropharyngeal route. Overall, rHVT-LT produced a partial protection against genotype VI ILTV infection.

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Effect of Pullet Vaccination on Development and Longevity of Immunity

Viruses ◽

10.3390/v11020135 ◽

2019 ◽

Vol 11 (2) ◽

pp. 135 ◽

Cited By ~ 5

Author(s):

Emily Aston ◽

Brian Jordan ◽

Susan Williams ◽

Maricarmen García ◽

Mark Jackwood

Keyword(s):

Clinical Signs ◽

Vaccination Program ◽

Economic Losses ◽

Respiratory Pathogens ◽

Infectious Laryngotracheitis Virus ◽

Vaccination Programs ◽

Live Attenuated Vaccines ◽

Specific Pathogen ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus

Avian respiratory disease causes significant economic losses in commercial poultry. Because of the need to protect long-lived poultry against respiratory tract pathogens from an early age, vaccination programs for pullets typically involve serial administration of a variety of vaccines, including infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and infectious laryngotracheitis virus (ILTV). Often the interval between vaccinations is only a matter of weeks, yet it is unknown whether the development of immunity and protection against challenge when vaccines are given in short succession occurs in these birds, something known as viral interference. Our objective was to determine whether serially administered, live attenuated vaccines against IBV, NDV, and ILTV influence the development and longevity of immunity and protection against challenge in long-lived birds. Based on a typical pullet vaccination program, specific-pathogen-free white leghorns were administered multiple live attenuated vaccines against IBV, NDV, and ILTV until 16 weeks of age (WOA), after which certain groups were challenged with IBV, NDV, or ILTV at 20, 24, 28, 32, and 36 WOA. Five days post-challenge, viral load, clinical signs, ciliostasis, tracheal histopathology, and antibody titers in serum and tears were evaluated. We demonstrate that pullets serially administered live attenuated vaccines against IBV, NDV, and ILTV were protected against homologous challenge with IBV, NDV, or ILTV for at least 36 weeks, and conclude that the interval between vaccinations used in this study (at least 2 weeks) did not interfere with protection. This information is important because it shows that a typical pullet vaccination program consisting of serially administered live attenuated vaccines against multiple respiratory pathogens can result in the development of protective immunity against each disease agent.

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Airborne Transmission of Vaccinal and Wild Type Infectious Laryngotracheitis Virus and Noninfectivity of Extracts of Excreta from Infected Chickens

Avian Diseases ◽

10.1637/aviandiseases-d-20-00073 ◽

2020 ◽

Vol 65 (1) ◽

Author(s):

Addisu Awukew Yegoraw ◽

Shahid Nazir ◽

Priscilla F. Gerber ◽

Stephen W. Walkden-Brown

Keyword(s):

Wild Type ◽

Airborne Transmission ◽

Infectious Laryngotracheitis Virus ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus

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In Vitro and In Vivo Relevance of Infectious Laryngotracheitis Virus gJ Proteins That Are Expressed from Spliced and Nonspliced mRNAs

Journal of Virology ◽

10.1128/jvi.79.2.705-716.2005 ◽

2005 ◽

Vol 79 (2) ◽

pp. 705-716 ◽

Cited By ~ 36

Author(s):

Walter Fuchs ◽

Dorothee Wiesner ◽

Jutta Veits ◽

Jens P. Teifke ◽

Thomas C. Mettenleiter

Keyword(s):

Severe Disease ◽

Progeny Virus ◽

Wild Type ◽

Infectious Laryngotracheitis Virus ◽

Live Virus ◽

Specific Antibodies ◽

Field Virus ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus

ABSTRACT The positional homologue in the infectious laryngotracheitis virus (ILTV) genome of the glycoprotein gJ gene of herpes simplex virus and the gp2 gene of equine herpesvirus 1 is expressed into four proteins of 85, 115, 160, and 200 kDa (J. Veits, B. Köllner, J. P. Teifke, H. Granzow, T. C. Mettenleiter, and W. Fuchs, Avian Dis. 47:330-342, 2003). RNA analyses revealed that these proteins are expressed from two different late (γ2) transcripts, an unspliced 5.5-kb and a spliced 4.3-kb mRNA that are translated into proteins of 985 and 611 amino acids, respectively. ILTV gJ is incorporated into virions and is modified by N- and O-linked glycosylation. After cotransfection of chicken cells with genomic DNA of a pathogenic ILTV strain and transfer plasmids, gJ-negative ILTV mutants could be isolated. In vitro growth studies demonstrated that deletion of the gJ gene has only minor effects on direct cell-to-cell spread as measured by plaque size. However, progeny virus titers of ILTV-ΔgJ were significantly reduced in comparison to those of the parental virus and a gJ rescue mutant. After experimental infection of chickens the gJ rescue mutant, like wild-type ILTV, caused severe disease and considerable mortality, whereas ILTV-ΔgJ was significantly attenuated. All immunized animals were protected against subsequent challenge infection with virulent ILTV. In sera collected after immunization with the gJ-rescue mutant or with wild-type ILTV, gJ-specific antibodies were detectable by immunofluorescence on cells that had been transfected with a gJ expression plasmid. As expected, no gJ-specific antibodies were found in sera obtained from chickens immunized with ILTV-ΔgJ. Thus, gJ deletion mutants of ILTV might be usable as attenuated live-virus vaccines. Furthermore, the gJ gene might constitute a reliable marker for serological discrimination between vaccinated and field virus-infected chickens.

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The UL47 gene of avian infectious laryngotracheitis virus is not essential for in vitro replication but is relevant for virulence in chickens

Journal of General Virology ◽

10.1099/vir.0.82533-0 ◽

2007 ◽

Vol 88 (3) ◽

pp. 732-742 ◽

Cited By ~ 31

Author(s):

Dorothee Helferich ◽

Jutta Veits ◽

Jens P. Teifke ◽

Thomas C. Mettenleiter ◽

Walter Fuchs

Keyword(s):

Deletion Mutant ◽

Cultured Cells ◽

Functional Characterization ◽

Wild Type Virus ◽

Wild Type ◽

Infectious Laryngotracheitis Virus ◽

Live Virus ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus

The genome of infectious laryngotracheitis virus (ILTV) exhibits several differences from those of other avian and mammalian alphaherpesviruses. One of them is the translocation of the conserved UL47 gene from the unique long (UL) to the unique short (US) genome region, where UL47 is inserted upstream of the US4 gene homologue. As in other alphaherpesviruses, UL47 encodes a major tegument protein of ILTV particles, whereas the US4 gene product is a non-structural glycoprotein, gG, which is secreted from infected cells. For functional characterization, an ILTV recombinant was isolated in which US4 together with the 3′-terminal part of UL47 was replaced by a reporter gene cassette encoding green fluorescent protein. From this virus, UL47 and US4 single-gene deletion mutants without foreign sequences were derived and virus revertants were also generated. In vitro studies revealed that both genes were non-essential for ILTV replication in cultured cells. Whereas US4-negative ILTV exhibited no detectable growth defects, maximum virus titres of the double deletion mutant and of UL47-negative ILTV were reduced about 10-fold compared with those of wild-type virus and rescued virus. Experimental infection of chickens demonstrated that UL47-negative ILTV was significantly attenuated in vivo and was shed in reduced amounts, whereas wild-type and rescued viruses caused severe disease and high mortality rates. As all immunized animals were protected against subsequent challenge infection with virulent ILTV, the UL47 deletion mutant might be suitable as a live-virus vaccine.

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Multilocus analysis of Gallid herpesvirus 1 in layer chickens in Iraq

Veterinary World ◽

10.14202/vetworld.2020.170-176 ◽

2020 ◽

Vol 13 (1) ◽

pp. 170-176

Author(s):

Mohammed Hamzah Abdulkadhim Al-Saadi

Keyword(s):

Genetic Relatedness ◽

Polymerase Chain Reaction Method ◽

Infectious Laryngotracheitis Virus ◽

Live Attenuated Vaccine ◽

Gallid Herpesvirus ◽

Infectious Laryngotracheitis ◽

Blotting Technique ◽

Herpesvirus 1 ◽

Laryngotracheitis Virus ◽

Chicken Sample

Background and Aim: Infectious laryngotracheitis virus (ILTV) causes a highly pathogenic respiratory disease that affects poultry. It is also known as Gallid herpesvirus 1. ILT prophylaxis measures often include using live attenuated vaccines. The live attenuated vaccine can, however, lead to the formation of new strains of ILTV as a result of vaccine reversion and recombination with field strains. Therefore, this study was performed to explore the multilocus variation of ILTV strains of field and vaccine origin. Samples were tested from two distinctive geographical areas in Iraq as little is known about the ILTV genetic diversity within these areas. Materials and Methods: The polymerase chain reaction method was utilized to generate sequencing templates of six highly polymorphic genes, including UL54, UL52, gB, ICP18.5, ICP4, and gJ in the layer chicken sample (n=15). The Western blotting technique was also employed to detect and estimate the native molecular weight of gE. Results: The results revealed an important degree of genetic relatedness between the field and vaccine strains across all genes. In addition, gE was found to be expressed natively at 49 kDa. Conclusion: The findings of this study may be used to improve the production process of the vaccine for more effective ILT prophylaxis and could further the understanding of epidemiologists and immunologists to better control ILT in the future.

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Genotyping of Infectious Laryngotracheitis Virus (ILTV) Isolates from Western Canadian Provinces of Alberta and British Columbia Based on Partial Open Reading Frame (ORF) a and b

Animals ◽

10.3390/ani10091634 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1634

Author(s):

Catalina Barboza-Solis ◽

Ana Perez Contreras ◽

Victor A. Palomino-Tapia ◽

Tomy Joseph ◽

Robin King ◽

...

Keyword(s):

British Columbia ◽

Open Reading Frame ◽

Nucleotide Polymorphisms ◽

Wild Type ◽

Infectious Laryngotracheitis Virus ◽

Group V ◽

Reading Frame ◽

Transmission Potential ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus

Infectious laryngotracheitis virus (ILTV) causes an acute upper respiratory disease in chickens called infectious laryngotracheitis (ILT). Live attenuated vaccines are effective in disease control; however, they have residual virulence, which makes them able to replicate, cause disease and revert to the original virulent form. Information is scarce on the molecular nature of ILTV that is linked to ILT in Canada. This study aims to determine whether isolates originating from ILT cases in Western Canada are a wild type or vaccine origin. Samples submitted for the diagnosis of ILT between 2009–2018 were obtained from Alberta (AB, n = 46) and British Columbia (BC, n = 9). For genotyping, a Sanger sequencing of open reading frame (ORF) a and b was used. A total of 27 from AB, and 5 from BC samples yielded a fragment of 1751 base pairs (bp). Three of the BC samples classified as group IV (CEO vaccine strains) and 2 as group V (CEO revertant). Of the AB samples, 22 samples clustered with group V, 3 with group VI (wild type), and 2 with group VII, VIII, and IX (wild type). Overall, 17 non-synonymous single nucleotide polymorphisms (SNPs) were detected. Further studies are underway to ascertain the virulence and transmission potential of these isolates.

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Experimental infection on the locally isolated avian infectious laryngotracheitis virus

The Iraqi Journal of Veterinary Medicine ◽

10.30539/iraqijvm.v41i1.69 ◽

2017 ◽

Vol 41 (1) ◽

pp. 1-4

Author(s):

Zaid Haddam Taha

Keyword(s):

Experimental Infection ◽

Post Infection ◽

Clinical Signs ◽

Elisa Test ◽

Infected Group ◽

Control Group ◽

Infectious Laryngotracheitis Virus ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus ◽

And Control

The aim of this study was to evaluate virulence of local isolated avian infectious laryngotracheitis virus in experimentally infected chicken. Forty chickens 10 weeks old were used for the experimental infection with the locally isolated infectious laryngotracheitis virus. Chickens were divided into three groups, the first group consisted from 20 chickens infected with isolated infectious laryngotracheitis virus (2×104.16 TCID 50/50 µl) via eyes and mouth drops (one drop for each). The second group consisted of 10 chickens (non-infected) in contact with infected group inoculated with maintenance media (Minimum essential medium) on their eyes, to observe if the infected group can spread the virus. The third group consisted from 10 chickens (non-infected) were left as a control group separated from other groups, inoculated with maintenance media (Minimum essential medium) on their eyes. Clinical signs and mortality were examined daily up to 12 days post infection. The main clinical signs were depression coughing and gasping with mild conjunctivitis and no mortality. Enzyme linked immunosorbent assay (ELISA) test was conducted on the collected sera of chickens before and after experimental infection with isolated virus. The results of ELISA test was negative for all groups of chickens before experiment and positive results for infected group with titer approximately ranging from (2534-7910); Measure of central tendency and dispersion were used with mean (4874.75) and stander error (355.96\ 13.6%); while negative results for contact group and control group. Eighteen chickens (10 weeks old) separately were divided into three groups (infected, contact and control) treated as mention above and were used for histopathological examination; the chickens were killed, two in each group at 24 hr., 48 hr. and 72 hr. post infection. The histopathological changes on trachea and larynx were intracellur inclusion bodies formation detected at 72hr., post infection for infected group only.

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Transmission of infectious laryngotracheitis virus vaccine and field strains: the role of degree of contact and transmission by whole blood, plasma and poultry dust

Veterinary Research ◽

10.1186/s13567-021-00959-1 ◽

2021 ◽

Vol 52 (1) ◽

Author(s):

Addisu A. Yegoraw ◽

Awol M. Assen ◽

Priscilla F. Gerber ◽

Stephen W. Walkden-Brown

Keyword(s):

Direct Contact ◽

Vaccine Virus ◽

Wild Type ◽

Airborne Transmission ◽

Infectious Laryngotracheitis Virus ◽

Infectious Laryngotracheitis ◽

Poultry Dust ◽

Laryngotracheitis Virus ◽

Type Strains

AbstractUnderstanding the mechanisms of transmission of infectious laryngotracheitis virus (ILTV) is critical to proper control as both vaccine and wild-type strains circulate within chicken flocks with potential adverse consequences. The relative efficiency of transmission by direct contact between chickens and airborne transmission has not been investigated. Furthermore, relatively high levels of ILTV DNA have been detected in poultry dust and blood but the infectivity of these is unknown. In this study, comparison of in-contact and airborne transmission of two vaccine and one field strain of ILTV revealed that all transmitted to 100% of in-contact birds by 6 days post-exposure (dpe). Airborne transmission without contact resulted in 100% transmission by 14 and 17 dpe for the wild-type and Serva vaccine virus but only 27% transmission by 21 dpe for the A20 vaccine virus. The infectivity of dust or extracts of dust and blood or plasma from infected chickens at various stages of infection was assessed by inoculation into susceptible chickens. There was no transmission by any of these materials. In conclusion, direct contact facilitated efficient ILTV transmission but the virus was unable to be transmitted by dust from infected chickens suggestive of a limited role in the epidemiology of ILTV.

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Pathogenic and Transmission Potential of Wildtype and Chicken Embryo Origin (CEO) Vaccine Revertant Infectious Laryngotracheitis Virus

Viruses ◽

10.3390/v13040541 ◽

2021 ◽

Vol 13 (4) ◽

pp. 541

Author(s):

Ana Perez-Contreras ◽

Catalina Barboza-Solis ◽

Shahnas M. Najimudeen ◽

Sylvia Checkley ◽

Frank van der Meer ◽

...

Keyword(s):

Chicken Embryo ◽

Severe Disease ◽

Clinical Signs ◽

Upper Respiratory Tract ◽

Infectious Laryngotracheitis Virus ◽

Live Attenuated Vaccines ◽

Transmission Potential ◽

Infectious Laryngotracheitis ◽

Laryngotracheitis Virus ◽

Embryo Origin

Infectious laryngotracheitis (ILT) is an infectious upper respiratory tract disease that impacts the poultry industry worldwide. ILT is caused by an alphaherpesvirus commonly referred to as infectious laryngotracheitis virus (ILTV). Vaccination with live attenuated vaccines is practiced regularly for the control of ILT. However, extensive and improper use of live attenuated vaccines is related to vaccine viruses reverting to virulence. An increase in mortality and pathogenicity has been attributed to these vaccine revertant viruses. Recent studies characterized Canadian ILTV strains originating from ILT outbreaks as related to live attenuated vaccine virus revertants. However, information is scarce on the pathogenicity and transmission potential of these Canadian isolates. Hence, in this study, the pathogenicity and transmission potential of two wildtype ILTVs and a chicken embryo origin (CEO) vaccine revertant ILTV of Canadian origin were evaluated. To this end, 3-week-old specific pathogen-free chickens were experimentally infected with each of the ILTV isolates and compared to uninfected controls. Additionally, naïve chickens were exposed to the experimentally infected chickens to mimic naturally occurring infection. Pathogenicity of each of these ILTV isolates was evaluated by the severity of clinical signs, weight loss, mortality, and lesions observed at the necropsy. The transmission potential was evaluated by quantification of ILTV genome loads in oropharyngeal and cloacal swabs and tissue samples of the experimentally infected and contact-exposed chickens, as well as in the capacity to produce ILT in contact-exposed chickens. We observed that the CEO vaccine revertant ILTV isolate induced severe disease in comparison to the two wildtype ILTV isolates used in this study. According to ILTV genome load data, CEO vaccine revertant ILTV isolate was successfully transmitted to naïve contact-exposed chickens in comparison to the tested wildtype ILTV isolates. Overall, the Canadian origin CEO vaccine revertant ILTV isolate possesses higher virulence, and dissemination potential, when compared to the wildtype ILTV isolates used in this study. These findings have serious implications in ILT control in chickens.

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