Attenuation and protection efficacy of ORF C gene-deleted recombinant of infectious laryngotracheitis virus

Garcı́a, Maricarmen; Spatz, Stephen J.; Cheng, Ying; Riblet, Sylva M.; Volkening, Jeremy D.; Schneiders, Gustavo H.

doi:10.1099/jgv.0.000521

Cited by 17 publications

(9 citation statements)

References 44 publications

(58 reference statements)

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“…This vaccine also offers the potential to discriminate between vaccinated birds and birds infected with wildtype viruses using differential PCR [33] or ELISAs [19] in DIVA (differentiation of infected and vaccinated animals) control programmes. Although a number of gene-deleted ILTV strains have been shown to have in vivo phenotypes that may make them suitable for use as vaccines [12–16, 34–41], the ΔgG ILTV vaccine strain is the most extensively investigated of these deletion mutants, providing a high level of confidence in the performance of the vaccine under different conditions. This current study shows that the ΔgG ILTV vaccine strain is able to induce a high level of protection against a virulent recombinant field virus at a commercially feasible dose.…”

Section: Discussionmentioning

confidence: 99%

Determination of the minimum protective dose of a glycoprotein-G-deficient infectious laryngotracheitis virus vaccine delivered via eye-drop to week-old chickens

et al. 2018

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Infectious laryngotracheitis (ILT) is an upper respiratory tract disease of chickens that is caused by infectious laryngotracheitis virus (ILTV), an alphaherpesvirus. This disease causes significant economic loses in poultry industries worldwide. Despite widespread use of commercial live attenuated vaccines, many poultry industries continue to experience outbreaks of disease caused by ILTV. Efforts to improve the control of this disease have resulted in the generation of new vaccine candidates, including ILTV mutants deficient in virulence factors. A glycoprotein G deletion mutant vaccine strain of ILTV (ΔgG ILTV), recently licenced as Vaxsafe ILT (Bioproperties Pty Ltd), has been extensively characterised in vitro and in vivo, but the minimum effective dose required to protect inoculated animals has not been determined. This study performed a vaccination and challenge experiment to determine the minimum dose of ΔgG ILTV that, when delivered by eye-drop to seven-day-old specific pathogen-free chickens, would protect the birds from a robust challenge with a virulent field strain of virus (class 9 ILTV). A dose of 103.8 plaque forming units was the lowest dose capable of providing a high level of protection against challenge, as measured by clinical signs of disease, tracheal pathology and virus replication after challenge. This study has shown that the ΔgG ILTV vaccine strain is capable of inducing a high level of protection against a virulent field virus at a commercially feasible dose. These results lay the foundations upon which a commercial vaccine can be developed, thereby offering the potential to provide producers with another important tool to help control ILTV.

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Section: Discussionmentioning

confidence: 99%

Determination of the minimum protective dose of a glycoprotein-G-deficient infectious laryngotracheitis virus vaccine delivered via eye-drop to week-old chickens

et al. 2018

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“…KEYWORDS herpesvirus, recombination, replication, diversity, SNP genotyping assay, vaccine, infectious laryngotracheitis virus, ILTV I nfectious laryngotracheitis virus (ILTV; Gallid alphaherpesvirus 1) causes mild to severe respiratory tract disease in chickens that results in major economic losses in poultry industries throughout the world as a consequence of increased mortality, decreased weight gain, and decreased egg production (1). Live attenuated vaccines are widely used to help control disease caused by infection with ILTV in Asia (2-4), Australia (5)(6)(7)(8)(9), Europe (10) and the United States (11)(12)(13)(14). These vaccines are generally effective in controlling clinical disease, and although some of these vaccines may not entirely prevent ILTV replication, as measured by viral tires after challenge (15), they have been used successfully to curtail outbreaks of the disease in the United States (1).…”

Section: Importancementioning

confidence: 99%

Single Nucleotide Polymorphism Genotyping Analysis Shows That Vaccination Can Limit the Number and Diversity of Recombinant Progeny of Infectious Laryngotracheitis Viruses from the United States

Loncoman

Hartley

Coppo

et al. 2018

Appl Environ Microbiol

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Infectious laryngotracheitis (ILTV; Gallid alphaherpesvirus 1) causes mild to severe respiratory disease in poultry worldwide. Recombination in this virus under natural (field) conditions was first described in 2012 and more recently has been studied under laboratory conditions. Previous studies have revealed that natural recombination is widespread in ILTV and have also demonstrated that recombination between two attenuated ILTV vaccine strains generated highly virulent viruses that produced widespread disease within poultry flocks in Australia. In the United States, natural ILTV recombination has also been detected, but not as frequently as in Australia. To better understand recombination in ILTV strains originating from the United States, we developed a TaqMan single nucleotide polymorphism (SNP) genotyping assay to detect recombination between two virulent U.S. field strains of ILTV (63140 and 1874c5) under experimental in vivo conditions. We also tested the capacity of the Innovax-ILT vaccine (a recombinant vaccine using herpesvirus of turkeys as a vector) and the Trachivax vaccine (a conventionally attenuated chicken embryo origin vaccine) to reduce recombination. The Trachivax vaccine prevented ILTV replication, and therefore recombination, in the trachea after challenge. The Innovax-ILT vaccine allowed the challenge viruses to replicate and to recombine, but at a significantly lower rate than in an unvaccinated group of birds. Our results demonstrate that the TaqMan SNP genotyping assay is a useful tool to study recombination between these ILTV strains and also show that vaccination can limit the number and diversity of recombinant progeny viruses. IMPORTANCE Recombination allows alphaherpesviruses to evolve over time and become more virulent. Historically, characterization of viral vaccines in poultry have mainly focused on limiting clinical disease, rather than limiting virus replication, but such approaches can allow field viruses to persist and evolve in vaccinated populations. In this study, we vaccinated chickens with Gallid alphaherpesvirus 1 vaccines that are commercially available in the United States and then performed coinoculations with two field strains of virus to measure the ability of the vaccines to prevent field strains from replicating and recombining. We found that vaccination reduced viral replication, recombination, and diversity compared to those in unvaccinated chickens, although the extent to which this occurred differed between vaccines. We suggest that characterization of vaccines could include studies to examine the ability of vaccines to reduce viral recombination in order to limit the rise of new virulent field strains due to recombination, especially for those vaccines that are known not to prevent viral replication following challenge.

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“…The ILTV strain (63140/C/08/BR) was obtained from the pathogen repository bank at the Poultry Diagnostic and Research Center (PDRC, University of Georgia, Athens, GA) and used as the challenge virus [11,24]. A recombinant ILTV expressing the green fluorescent protein (ILTV/GFP) was used to infect LMH cell line (ATCC ® CRL-2117 ™ ) in order to measure neutralizing maternal antibody titers against ILTV [25]. LMH cells were cultured in Dulbecco's Modified Eagle Medium (DMEM, Life Technologies, Carlsbad, CA) supplemented with 10% fetal bovine serum (FBS, Life Technologies, Carlsbad, CA) and antibiotics (100U/ml Penicillin, 100µg/ml Streptomycin, 0.25µg/ml Amphotericin B, Thermo Scientific, Suwanee, GA) at 37°C in 5% CO 2 atmospheres.…”

Section: Vaccines Viruses and Cellsmentioning

confidence: 99%

Newcastle disease virus vectored infectious laryngotracheitis vaccines protect commercial broiler chickens in the presence of maternally derived antibodies

Spatz

et al. 2017

Vaccine

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Newcastle disease virus (NDV) recombinants expressing the infectious laryngotracheitis virus (ILTV) glycoproteins B and D have previously been demonstrated to confer complete clinical protection against virulent ILTV and NDV challenges in naive chickens. We extended this study to assess whether maternally derived antibody (MDA) against NDV and ILTV would interfere with protection in vaccinated broiler chickens. Chickens with a mean NDV MDA hemagglutination inhibition (HI) titer of 6.4 (log) and detectable ILTV neutralization (VN) antibodies at hatch were vaccinated with rLS/ILTV-gB or rLS/ILTV-gD at 1 or 10day of age (DOA) or on both days. Groups of birds vaccinated with the commercial ILT vaccines (FP-LT and CEO) or sham inoculated were also included in this study. All vaccinated birds were challenged with virulent ILTV strain at 21 DOA. By that time, NDV HI titers declined to 2.6 (log) in unvaccinated birds, whereas the HI titers in NDV vectored vaccine groups increased to 3.5-6.3 (log). At standard dosages, both vaccine candidates conferred significant clinical protection; however, the protection elicited by the rLS/ILTV-gD was superior to that of rLS/ILTV-gB. Recombinant rLS/ILTV-gD reduced ILTV shedding from tracheal and ocular tissues by approximately 3 log TCID. Notably, there was no improvement in protection after booster vaccination at 10 DOA. Overall results indicate that the presence of maternal antibodies to NDV and ILTV did not significantly interfere with the ability of the NDV LaSota strain-vectored ILTV gB and gD vaccine candidates to elicit protective immunity against infectious laryngotracheitis.

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Attenuation and protection efficacy of ORF C gene-deleted recombinant of infectious laryngotracheitis virus

Cited by 17 publications

References 44 publications

Determination of the minimum protective dose of a glycoprotein-G-deficient infectious laryngotracheitis virus vaccine delivered via eye-drop to week-old chickens

Determination of the minimum protective dose of a glycoprotein-G-deficient infectious laryngotracheitis virus vaccine delivered via eye-drop to week-old chickens

Single Nucleotide Polymorphism Genotyping Analysis Shows That Vaccination Can Limit the Number and Diversity of Recombinant Progeny of Infectious Laryngotracheitis Viruses from the United States

Newcastle disease virus vectored infectious laryngotracheitis vaccines protect commercial broiler chickens in the presence of maternally derived antibodies

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