Efficacy of a commercial vaccine against different strains of rabbit haemorrhagic disease virus

Read, Andrew J.; Kirkland, PD

doi:10.1111/avj.12600

Cited by 17 publications

(22 citation statements)

References 12 publications

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“…The level of RNA persistence in this control (2.9 log 10 copies/µg liver) is consistent with previously internal data collected for GI.2-CH.2012 challenge, after which 100% of surviving controls were still PCR-positive 14 dpc (range: 3 to 4.5 log 10 copies) (Le Minor, unpublished data). In addition, several experimental studies showed that vaccination against GI.1 or GI.2 lagoviruses, regardless of the type of vaccine (inactivated vaccines, recombinant or an experimental subunit), is unable to ensure complete "sterile immunity" after challenge, as carriers of low amounts of viral RNA are identified (Gall and Schirrmeier, 2006;Spikey, et al, 2012;Read and Kirkland, 2017). However, until now, none of the experiments have been able to prove that the persistence of RNA in different organs, including spleen and liver, is linked to the persistence of infectious virus particles (Shien et al, 2000;Forrester et al, 2003;Gall et al, 2007;Strive et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Rabbit haemorrhagic disease: experimental study of a recent highly pathogenic GI.2/RHDV2/b strain and evaluation of vaccine efficacy

Minor¹,

Boucher

Joudou³

et al. 2019

World Rabbit Sci.

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In 2010, a variant of the rabbit haemorrhagic disease virus (RHDV) belonging to a new GI.2 genotype was identified in France and rapidly spread worldwide. Due to antigenic difference, new vaccines including G1.2 strains have been developed to confer adequate protection. An increase in the pathogenicity of the circulating strains was recently reported. The objective of this experimental study was to characterise the infection with a highly pathogenic GI.2/RHDV2/b isolate (2017) and assess the efficacy of Filavac VHD K C+V vaccine (Filavie) against this strain. Four and 10-wk-old specific pathogen-free rabbits were inoculated with a recommended dose of vaccine. After 7 d, controls and vaccinated rabbits were challenged and clinically monitored for 14 d. All animals were necropsied and blood, organs and urine were sampled for quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis. In adult groups, regular nasal and rectal swabbing were performed, and faeces were collected after death to monitor RNA shedding. In control groups, the challenge strain induced acute RHD between 31 and 72 h post-inoculation, with a mortality rate of 100% for kits and 89% for adult rabbits. Except for a shorter mean time to death in kits, similar clinical signs and lesions were observed between age groups. The vaccination significantly prevented all mortality, clinical signs, detection of viral RNA in serum and gross lesions in kits and adult rabbits. In adult groups, we also demonstrated that vaccine significantly protected from detectable RNA shedding via naso-conjunctival and rectal routes. Two weeks after challenge, RNA copies were not detected by PCR in the liver, spleen, lungs, kidneys, faeces and urine of vaccinated adult rabbits. The findings for kits were similar, except that very low levels of RNA were present in the liver and spleen of a few rabbits. These data show that immunisation prevented any significant viral multiplication and/or allowed a rapid clearance. We concluded that, despite the quick evolution of GI.2/RHDV2/b strains, the protection conferred by the vaccine remains adequate. In the context of coexistence of both GI.1 and GI.2 genotypes in some countries, with the circulation of multiples recombinant viruses, the vaccination should be based on the association of strains from both genotypes.

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Section: Discussionmentioning

confidence: 99%

Rabbit haemorrhagic disease: experimental study of a recent highly pathogenic GI.2/RHDV2/b strain and evaluation of vaccine efficacy

Minor¹,

Boucher

Joudou³

et al. 2019

World Rabbit Sci.

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“…The genome sequence of this isolate is available under Genbank accession MW467791. For titration, groups of six rabbits were inoculated intramuscularly with 10-fold serial dilutions of the concentrated virus stock and the Reed-Muench method was used to determine the 50% endpoint [ 42 ]. Individual vials of freeze-dried virus stock (Elizabeth Macarthur Agricultural Institute, NSW, Australia) were reconstituted in sterile water immediately prior to each trial and diluted to the required dose.…”

Section: Methodsmentioning

confidence: 99%

Age and Infectious Dose Significantly Affect Disease Progression after RHDV2 Infection in Naïve Domestic Rabbits

Hall

King

O’Connor

et al. 2021

Viruses

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Rabbit haemorrhagic disease virus 2 (RHDV2 or GI.2, referring to any virus with lagovirus GI.2 structural genes) is a recently emerged calicivirus that causes generalised hepatic necrosis and disseminated intravascular coagulation leading to death in susceptible lagomorphs (rabbits and hares). Previous studies investigating the virulence of RHDV2 have reported conflicting results, with case fatality rates ranging from 0% to 100% even within a single study. Lagoviruses are of particular importance in Australia and New Zealand where they are used as biocontrol agents to manage wild rabbit populations, which threaten over 300 native species and result in economic impacts in excess of $200 million AUD annually to Australian agricultural industries. It is critically important that any pest control method is both highly effective (i.e., virulent, in the context of viral biocontrols) and has minimal animal welfare impacts. To determine whether RHDV2 might be a suitable candidate biocontrol agent, we investigated the virulence and disease progression of a naturally occurring Australian recombinant RHDV2 in both 5-week-old and 11-week-old New Zealand White laboratory rabbits after either high or low dose oral infection. Objective measures of disease progression were recorded through continuous body temperature monitoring collars, continuous activity monitors, and twice daily observations. We observed a 100% case fatality rate in both infected kittens and adult rabbits after either high dose or low dose infection. Clinical signs of disease, such as pyrexia, weight loss, and reduced activity, were evident in the late stages of infection. Clinical disease, i.e., welfare impacts, were limited to the period after the onset of pyrexia, lasting on average 12 h and increasing in severity as disease progressed. These findings confirm the high virulence of this RHDV2 variant in naïve rabbits. While age and infectious dose significantly affected disease progression, the case fatality rate was consistently 100% under all conditions tested.

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“…A commercially produced preparation of RHDVa‐K5 that had been titrated in rabbits (Read & Kirkland, ) was used as inoculum to produce hyperimmune sera, diluted to 10,000 RID 50 /ml (Elizabeth Macarthur Agricultural Institute, Menangle, Australia). RHDVa‐Aus inoculum was prepared from a 2% of clarified liver homogenate of RHDVa‐Aus (Ber‐3, GenBank # KY628310) (Mahar, Read, et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…A commercially produced preparation of RHDVa-K5 that had been titrated in rabbits (Read & Kirkland, 2017) was used as inoculum to produce hyperimmune sera, diluted to 10,000 RID 50 /ml (Elizabeth Macarthur Agricultural Institute, Menangle, Australia).…”

Section: Production Of Antigen Virus Inoculum and Experimental Vacmentioning

confidence: 99%

Retrospective serological analysis reveals presence of the emerging lagovirus RHDV2 in Australia in wild rabbits at least five months prior to its first detection

Strive

Piper

Huang

et al. 2019

Transbound Emerg Dis

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The lagovirus rabbit haemorrhagic disease virus (RHDV) has been circulating in Australia since the mid‐1990s when it was released to control overabundant rabbit populations. In recent years, the viral diversity of different RHDVs in Australia has increased, and currently four different types of RHDV are known to be circulating. To allow for ongoing epidemiological studies and impact assessments of these viruses on Australian wild rabbit populations, it is essential that serological tools are updated. To this end, reference sera were produced against all four virulent RHDVs (RHDV, RHDV2 and two different strains of RHDVa) known to be present in Australia and tested in a series of available immunological assays originally developed for the prototype RHDV, to assess patterns of cross‐reactivity and the usefulness of these assays to detect lagovirus antibodies, either in a generic or specific manner. Enzyme‐linked immunosorbent assays (ELISAs) developed to detect antibody isotypes IgM, IgA and IgG were sufficiently cross‐reactive to detect antibodies raised against all four virulent lagoviruses. For the more specific detection of antibodies to the antigenically more different RHDV2, a competition ELISA was adapted using RHDV2‐specific monoclonal antibodies in combination with Australian viral antigen. Archival serum banks from a long‐term rabbit monitoring site where rabbits were sampled quarterly over a period of 6 years were re‐screened using this assay and revealed serological evidence for the arrival of RHDV2 in this population at least 5 months prior to its initial detection in Australia in a dead rabbit in May 2015. The serological methods and reference reagents described here will provide valuable tools to study presence, prevalence and impact of RHDV2 on Australian rabbit populations; however, the discrimination of different antigenic variants of RHDVs as well as mixed infections at the serological level remains challenging.

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Efficacy of a commercial vaccine against different strains of rabbit haemorrhagic disease virus

Abstract: All vaccinated rabbits were protected against rabbit haemorrhagic disease, indicating that the Cylap® vaccine is effective against both strains of the virus under experimental conditions.

Cited by 17 publications

References 12 publications

Rabbit haemorrhagic disease: experimental study of a recent highly pathogenic GI.2/RHDV2/b strain and evaluation of vaccine efficacy

Rabbit haemorrhagic disease: experimental study of a recent highly pathogenic GI.2/RHDV2/b strain and evaluation of vaccine efficacy

Age and Infectious Dose Significantly Affect Disease Progression after RHDV2 Infection in Naïve Domestic Rabbits

Retrospective serological analysis reveals presence of the emerging lagovirus RHDV2 in Australia in wild rabbits at least five months prior to its first detection

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