RESUMO
Rabbit haemorrhagic disease viruses (RHDV) belong to the family Caliciviridae, genus Lagovirus europaeus, genogroup GI, comprising four genotypes GI.1-GI.4, of which the genotypes GI.1 and GI.2 are pathogenic RHD viruses, while the genotypes GI.3 and GI.4 are non-pathogenic RCV (Rabbit calicivirus) viruses. Among the pathogenic genotypes GI.1 and GI.2 of RHD viruses, an antigenic variant of RHDV, named RHDVa-now GI.1a-RHDVa, was distinguished in 1996; and in 2010, a variant of RHDV-named RHDVb, later RHDV2 and now GI.2-RHDV2/b-was described; and recombinants of these viruses were registered. Pathogenic viruses of the genotype GI.1 were the cause of a disease described in 1984 in China in domestic (Oryctolagus (O.) cuniculus domesticus) and wild (O. cuniculus) rabbits, characterised by a very rapid course and a mortality rate of 90-100%, which spread in countries all over the world and which has been defined since 1989 as rabbit haemorrhagic disease. It is now accepted that GI.1-RHDV, including GI.1a-RHDVa, cause the predetermined primary haemorrhagic disease in domestic and wild rabbits, while GI.2-RHDV2/b cause it not only in rabbits, including domestic rabbits' young up to 4 weeks and rabbits immunised with rabbit haemorrhagic disease vaccine, but also in five various species of wild rabbits and seven different species of hares, as well as wild ruminants: mountain muskoxen and European badger. Among these viruses, haemagglutination-positive, doubtful and harmful viruses have been recorded and described and have been shown to form phylogenogroups, immunotypes, haematotypes and pathotypes, which, together with traits that alter and expand their infectious spectrum (rabbit, hare, wild ruminant, badger and various rabbit and hare species), are the determinants of their pathogenicity (infectivity) and immunogenicity and thus shape their virulence. These relationships are the aim of our consideration in this article.
Assuntos
Infecções por Caliciviridae , Vírus da Doença Hemorrágica de Coelhos , Animais , Vírus da Doença Hemorrágica de Coelhos/genética , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Vírus da Doença Hemorrágica de Coelhos/imunologia , Infecções por Caliciviridae/virologia , Infecções por Caliciviridae/veterinária , Infecções por Caliciviridae/imunologia , Coelhos , Genótipo , Virulência , FilogeniaRESUMO
Vimentin is an intermediate filament, a cytoskeleton protein expressed mainly in cells of mesenchymal origin. Increasing evidence indicates that vimentin could play a key role in viral infections. Therefore, changes in tissue and extracellular vimentin expression and associated signal trails may determine/protect the fate of cells and the progression of disease caused by viral infection. Rabbit hemorrhagic disease virus (RHDV), genotype GI.1, is an etiological agent that causes a severe and highly lethal disease-RHD (rabbit hemorrhagic disease). This article evaluates the gene and protein expression of vimentin in the tissues (liver, lungs, spleen, and kidneys) and serum of rabbits experimentally infected with two RHDV variants (GI.1a). The VIM mRNA expression levels in the tissues were determined using reverse transcription quantitative real-time PCR (RT-qPCR). In addition, the amount of vimentin protein in the serum was analyzed by an ELISA test. We observed significantly elevated expression levels of VIM mRNA and protein in the liver and kidney tissues of infected rather than healthy rabbits. In addition, VIM mRNA expression was increased in the lung tissues; meanwhile, we observed only protein-enhanced vimentin in the spleen. The obtained results are significant and promising, as they indicate the role of vimentin in RHDV infection and the course of RHD. The role of vimentin in RHDV infection could potentially rely on the one hand, on creating a cap of invisibility against the intracellular viral spread, or, on the other hand, after the damage of cells, vimentin could act as a signal of tissue damage.
Assuntos
Infecções por Caliciviridae/veterinária , Expressão Gênica , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Interações Hospedeiro-Patógeno/genética , Vimentina/genética , Vimentina/metabolismo , Animais , Infecções por Caliciviridae/sangue , Infecções por Caliciviridae/virologia , Feminino , Vírus da Doença Hemorrágica de Coelhos/genética , Masculino , Coelhos , Baço/virologiaRESUMO
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.
Assuntos
Doenças dos Animais/patologia , Doenças dos Animais/virologia , Infecções por Caliciviridae/veterinária , Vírus da Doença Hemorrágica de Coelhos , Fatores Etários , Animais , Progressão da Doença , Feminino , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Masculino , Coelhos , VirulênciaRESUMO
Viral diseases, whether of animals or humans, are normally considered as problems to be managed. However, in Australia, two viruses have been used as landscape-scale therapeutics to control European rabbits (Oryctolagus cuniculus), the preeminent invasive vertebrate pest species. Rabbits have caused major environmental and agricultural losses and contributed to extinction of native species. It was not until the introduction of Myxoma virus that effective control of this pest was obtained at a continental scale. Subsequent coevolution of rabbit and virus saw a gradual reduction in the effectiveness of biological control that was partially ameliorated by the introduction of the European rabbit flea to act as an additional vector for the virus. In 1995, a completely different virus, Rabbit hemorrhagic disease virus (RHDV), escaped from testing and spread through the Australian rabbit population and again significantly reduced rabbit numbers and environmental impacts. The evolutionary pressures on this virus appear to be producing quite different outcomes to those that occurred with myxoma virus and the emergence and invasion of a novel genotype of RHDV in 2014 have further augmented control. Molecular studies on myxoma virus have demonstrated multiple proteins that manipulate the host innate and adaptive immune response; however the molecular basis of virus attenuation and reversion to virulence are not yet understood.
Assuntos
Agentes de Controle Biológico , Infecções por Caliciviridae/veterinária , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Myxoma virus/patogenicidade , Mixomatose Infecciosa/virologia , Reprodução , Animais , Austrália , Coevolução Biológica , Infecções por Caliciviridae/mortalidade , Infecções por Caliciviridae/virologia , Feminino , Expressão Gênica , Genótipo , Vírus da Doença Hemorrágica de Coelhos/genética , Interações Hospedeiro-Patógeno/genética , Insetos Vetores/virologia , Espécies Introduzidas , Masculino , Myxoma virus/genética , Mixomatose Infecciosa/mortalidade , Mixomatose Infecciosa/patologia , Coelhos , Sifonápteros/virologia , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
Rabbit hemorrhagic disease virus (RHDV) is the causative agent of rabbit hemorrhagic disease (RHD), and its infection results in mortality of 70-90% in farmed and wild rabbits. RHDV is thought to replicate strictly in rabbits. However, there are also reports showing that gene segments from the RHDV genome or antibodies against RHDV have been detected in other animals. Here, we report the detection and isolation of a RHDV from diseased Alpine musk deer (Moschussifanicus). The clinical manifestations in those deer were sudden death without clinical signs and hemorrhage in the internal organs. To identify the potential causative agents of the disease, we used sequence independent single primer amplification (SISPA) to detect gene segments from viruses in the tissue samples collected from the dead deer. From the obtained sequences, we identified some gene fragments showing very high nucleotide sequence similarity with RHDV genome. Furthermore, we identified caliciviral particles using an electron microscope in the samples. The new virus was designated as RHDV GS/YZ. We then designed primers based on the genome sequence of an RHDV strain CD/China to amplify and sequence the whole genome of the virus. The genome of the virus was determined to be 7437 nucleotides in length, sharing the highest genome sequence identity of 98.7% with a Chinese rabbit strain HB. The virus was assigned to the G2 genotype of RHDVs according to the phylogenetic analyses based on both the full-length genome and VP60 gene sequences. Animal experiments showed that GS/YZ infection in rabbits resulted in the macroscopic and microscopic lesions similar to that caused by the other RHDVs. This is the first report of RHDV isolated from Alpine musk deer, and our findings extended the epidemiology and host range of RHDV.
Assuntos
Infecções por Caliciviridae/veterinária , Cervos/virologia , Genoma Viral , Vírus da Doença Hemorrágica de Coelhos/classificação , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Animais , Infecções por Caliciviridae/mortalidade , China/epidemiologia , Feminino , Genótipo , Vírus da Doença Hemorrágica de Coelhos/isolamento & purificação , Especificidade de Hospedeiro , Masculino , Parques Recreativos , Filogenia , Coelhos , Proteínas Estruturais Virais/genéticaRESUMO
Recently, multiple infectious organisms have been identified as the cause of emerging diseases in lagomorphs. The most important of these emerging diseases is rabbit hemorrhagic disease virus (RHDV) type 2, a new variant with differences in pathogenicity to classical RHDV. Hepatitis E is considered an emerging zoonotic infectious disease, with widespread prevalence in many different rabbit populations. Mycobacteriosis has been recently reported in other captive domestic rabbit populations. This article provides a recent review of the published literature on emerging infectious diseases in rabbits, including farmed, laboratory, and pet rabbits, some of which have zoonotic potential.
Assuntos
Infecções por Caliciviridae/veterinária , Doenças Transmissíveis Emergentes/veterinária , Hepatite E/veterinária , Infecções por Mycobacterium/veterinária , Infecções por Parvoviridae/veterinária , Infecções por Picornaviridae/veterinária , Animais , Infecções por Caliciviridae/epidemiologia , Doenças Transmissíveis Emergentes/epidemiologia , Vírus da Doença Hemorrágica de Coelhos/isolamento & purificação , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Hepatite E/epidemiologia , Humanos , Infecções por Mycobacterium/epidemiologia , Infecções por Parvoviridae/epidemiologia , Infecções por Picornaviridae/epidemiologia , Coelhos , ZoonosesRESUMO
The rabbit hemorrhagic disease virus (RHDV), which belongs to the family Caliciviridae and the genus Lagovirus, causes lethal fulminant hepatitis in rabbits. RHDV decreases the activity of antioxidant enzymes regulated by Nrf2 in the liver. Antioxidants are important for the maintenance of cellular integrity and cytoprotection. However, the mechanism underlying the regulation of the Nrf2-antioxidant response element (ARE) signaling pathway by RHDV remains unclear. Using isobaric tags for relative and absolute quantification (iTRAQ) technology, the current study demonstrated that RHDV inhibits the induction of ARE-regulated genes and increases the expression of the p50 subunit of the NF-κB transcription factor. We showed that RHDV replication causes a remarkable increase in reactive oxygen species (ROS), which is simultaneously accompanied by a significant decrease in Nrf2. It was found that nuclear translocation of Keap1 plays a key role in the nuclear export of Nrf2, leading to the inhibition of Nrf2 transcriptional activity. The p50 protein partners with Keap1 to form the Keap1-p50/p65 complex, which is involved in the nuclear translocation of Keap1. Moreover, upregulation of Nrf2 protein levels in liver cell nuclei by tert-butylhydroquinone (tBHQ) delayed rabbit deaths due to RHDV infection. Considered together, our findings suggest that RHDV inhibits the Nrf2-dependent antioxidant response via nuclear translocation of Keap1-NF-κB complex and nuclear export of Nrf2 and provide new insight into the importance of oxidative stress during RHDV infection.IMPORTANCE Recent studies have reported that rabbit hemorrhagic disease virus (RHDV) infection reduced Nrf2-related antioxidant function. However, the regulatory mechanisms underlying this process remain unclear. The current study showed that the NF-κB p50 subunit partners with Keap1 to form the Keap1-NF-κB complex, which plays a key role in the inhibition of Nrf2 transcriptional activity. More importantly, upregulated Nrf2 activity delayed the death of RHDV-infected rabbits, strongly indicating the importance of oxidative damage during RHDV infection. These findings may provide novel insights into the pathogenesis of RHDV.
Assuntos
Antioxidantes/metabolismo , Infecções por Caliciviridae/metabolismo , Vírus da Doença Hemorrágica de Coelhos/imunologia , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , NF-kappa B/metabolismo , Animais , Elementos de Resposta Antioxidante , Antioxidantes/farmacologia , Infecções por Caliciviridae/imunologia , Infecções por Caliciviridae/patologia , Núcleo Celular/metabolismo , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica , Células HEK293 , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Humanos , Hidroquinonas , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Fígado/lesões , Fígado/metabolismo , Fígado/patologia , Fator 2 Relacionado a NF-E2/genética , Estresse Oxidativo , Proteômica , Coelhos , Transdução de Sinais/efeitos dos fármacos , Fator de Transcrição RelA , Replicação ViralRESUMO
Rabbit hemorrhagic disease (RHD) is a lethal disease in rabbits caused by RHD virus (RHDV). Protection is only possible through vaccination. A new virus variant (RHDV2) which emerged in 2010 in France differed from the classical RHDV1 variant in certain aspects and vaccines against RHDV1 induced limited cross protection only. In a previous study, we designed a recombinant baculovirus based RHDV2-VP1 vaccine, which provided a protective immunity in rabbits against RHDV2. In the present study this newly created vaccine is characterized with regard to onset and duration of protection, and possible cross protection against classical RHDV1. Furthermore, humoral and cellular immune mechanisms in vaccinated and infected rabbits were analyzed. In all experiments, the recombinant vaccine was compared to a conventional liver-based RHDV2 vaccine. The RHDV2-VP1 vaccine induced a protective immune response already seven days after single vaccination and fully protected for at least 14â¯months. A booster vaccination 21â¯days after the first had a negative influence on long-term protection. The cross protection provided by the RHDV2-VP1 vaccine against classical RHDV1 was limited since only 50% of vaccinated rabbits survived the infection. Conclusively, the new, baculovirus-based RHDV2-VP1 vaccine has the potential to protect rabbits against the infection with RHDV2, blocks completely the disease progression and prevents the spread of RHDV2 at the population level.
Assuntos
Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Animais , Baculoviridae/imunologia , Baculoviridae/patogenicidade , Infecções por Caliciviridae/imunologia , Infecções por Caliciviridae/prevenção & controle , Vírus da Doença Hemorrágica de Coelhos/imunologia , Imunidade Celular/fisiologia , Imunidade Humoral/fisiologia , CoelhosRESUMO
Caliciviruses use a termination/reinitiation mechanism for translation of their minor capsid protein VP2. A sequence element of about 80 nucleotides denoted 'termination upstream ribosomal binding site' (TURBS) is crucial for reinitiation. RNA secondary structure probing and computer aided secondary structure prediction revealed a rather low degree of secondary structure determinants for the TURBS of the rabbit hermorrhagic disease virus. Mutation analysis showed that prevention of duplex formation had major impact on the VP2 expression levels. Restoration of complementarity of the respective sequences by reciprocal mutation at least partially restored reinitiating rates. Synthetic TURBS structures preserving only the secondary structure forming sequences and the known short motifs important for TURBS function were found to drive reinitiation when the altered sequence could be predicted to allow establishment of the crucial secondary structures of the TURBS.
Assuntos
Infecções por Caliciviridae/genética , Proteínas do Capsídeo/genética , Vírus da Doença Hemorrágica de Coelhos/genética , Relação Estrutura-Atividade , Animais , Sítios de Ligação , Infecções por Caliciviridae/virologia , Regulação Viral da Expressão Gênica/genética , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Mutação , Biossíntese de Proteínas/genética , Coelhos , Ribossomos/genéticaRESUMO
Rabbit hemorrhagic disease virus (RHDV) is a highly contagious calicivirus that causes peracute hemorrhagic fever and frequently kills rabbits before an effective adaptive immune response can be developed. In Australia and New Zealand, RHDV is employed to manage wild European rabbit ( Oryctolagus cuniculus) populations. Although there is no evidence that RHDV replicates in animals other than lagomorphs, the detection of RHDV-specific antibodies and RHDV RNA in mice and other species has raised concerns about the host specificity of the virus. To investigate the replication potential of RHDV in mice ( Mus musculus), standard laboratory mice and knockout animals that lack a functional interferon type I receptor were challenged with high doses of RHDV. None of the animals developed clinical signs of illness, and temporal quantification of the viral RNA by real-time PCR did not reveal signs of virus amplification. These data suggest that RHDV cannot replicate in mice-not even in animals with a severely compromised innate immune system.
Assuntos
Infecções por Caliciviridae/virologia , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Especificidade de Hospedeiro , Hospedeiro Imunocomprometido , Animais , Fígado/virologia , Camundongos , Camundongos Knockout , RNA Viral/isolamento & purificação , Receptor de Interferon alfa e beta/genética , Baço/virologia , Carga ViralRESUMO
RHDVb has become the dominant RHDV on the Iberian Peninsula. A better understanding of its pathogenicity is required to aid control measures. Thus, the clinical course, humoral immune response, viraemia and kinetics of RHDV-N11 (a Spanish RHDVb isolate) infection in different tissues at both viral RNA and protein levels were studied in experimentally infected young and adult rabbits. The case fatality rate differed between the two age groups, with 21% of kits succumbing while no deaths were observed in adults. Fever and viremia were strongly associated with death, which occurred 48â¯h post infection (PI) too fast for an effective humoral immune response to be mounted. A significant effect on the number of viral RNA copies with regard to the variables age, tissue and time PI (pâ¯<â¯0.0001 in all cases) was detected. Histological lesions in infected rabbits were consistently more frequent and severe in liver and spleen and additionally intestine in kits, these tissues containing the highest levels of viral RNA and protein. Although no adults showed lesions or virus antigen in intestine, both kits and adults maintained steady viral RNA levels from days 1 to 7 PI in this organ. Analysis revealed the fecal route as the main dissemination route of RHDV-N11. Subclinically infected rabbits had detectable viral RNA in their faeces for up to seven days and thus may play an important role spreading the virus. This study allows a better understanding of the transmission of this virus and improvement of the control strategies for this disease.
Assuntos
Infecções por Caliciviridae/veterinária , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Fatores Etários , Animais , Antígenos Virais , Infecções por Caliciviridae/virologia , Fezes/virologia , Vírus da Doença Hemorrágica de Coelhos/classificação , Vírus da Doença Hemorrágica de Coelhos/genética , Filogenia , RNA Viral/genética , Coelhos , Baço/virologia , Viremia , VirulênciaRESUMO
European rabbits (Oryctolagus cuniculus) are severely affected by rabbit haemorrhagic disease (RHD). Caused by a lagovirus, the disease leads to losses in the rabbit industry and has implications for wildlife conservation. Past RHD outbreaks have been caused by GI.1/RHDV genotype viruses. A new virus belonging to the GI.2/RHDV2/b genotype emerged in 2010, quickly spreading and replacing the former in several countries; however, limited data are available on its pathogenicity and epidemiological factors. The present work extends these issues and evaluates cross-protection between both genotypes. Ninety-four and 88 domestic rabbits were challenged with GI.2/RHDV2/b and GI.1b/RHDV variant isolates, respectively. Cross-protection was determined by a second challenge on survivors with the corresponding strain. Mortality by GI.2/RHDV2/b was highly variable due to unknown individual factors, whereas mortality by GI.1b/RHDV was associated with age. Mortality in rabbitsâ¯<â¯4 weeks old was 84%, higher than previously reported. Cross-protection was not identical between the two viruses because the ratio of mortality rate ratios for the first and second challenges was 3.80⯱â¯2.68 times higher for GI.2/RHDV2/b than it was for GI.1b/RHDV. Rabbit susceptibility to GI.2/RHDV2/b varied greatly and appeared to be modulated by the innate functionality of the immune response and/or its prompt activation by other pathogens. GI.1b/RHDV pathogenicity appeared to be associated with undetermined age-related factors. These results suggest that GI.2/RHDV2/b may interact with other pathogens at the population level but does not satisfactorily explain the GI.1b/RHDV virus's quick replacement.
Assuntos
Infecções por Caliciviridae/veterinária , Proteção Cruzada/imunologia , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Doença Aguda , Fatores Etários , Animais , Infecções por Caliciviridae/epidemiologia , Infecções por Caliciviridae/imunologia , Infecções por Caliciviridae/mortalidade , Surtos de Doenças , Genótipo , Vírus da Doença Hemorrágica de Coelhos/classificação , Vírus da Doença Hemorrágica de Coelhos/genética , Vírus da Doença Hemorrágica de Coelhos/imunologia , Filogenia , Coelhos , Espanha/epidemiologia , VirulênciaRESUMO
Mortality caused by rabbit haemorrhagic disease virus (RHDV) in wild rabbits is reduced in parts of Australia where the related, non-pathogenic calicivirus RCV-A1 is endemic. Laboratory experiments previously showed that prior infection with RCV-A1 enabled rabbits to better withstand subsequent infection with highly virulent RHDV, and this was assumed to explain higher survival. Here, we analyse serological data from the field suggesting that reduced mortality rates among wild rabbits may also result from rabbits previously infected with RCV-A1 having a reduced likelihood of RHDV infection. We discuss the possible mechanisms underlying this finding and its implications. The methods we describe for analysing field data gave far greater insights into epidemiological processes and virus interactions than gained from reporting basic seroprevalence rates alone.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Caliciviridae/mortalidade , Infecções por Caliciviridae/veterinária , Proteção Cruzada , Vírus da Doença Hemorrágica de Coelhos/imunologia , Animais , Austrália/epidemiologia , Infecções por Caliciviridae/imunologia , Ensaio de Imunoadsorção Enzimática/veterinária , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Coelhos , Estudos SoroepidemiológicosRESUMO
Robinia pseudoacacia flower, a common component in traditional Chinese medicine, has long been well-known for its high pharmaceutical value. This study aimed to assess the immunopotentiating effects of Taishan Robinia Pseudoacacia polysaccharides (TRPPS) in rabbits inoculated with a rabbit haemorrhagic disease virus (RHDV) inactivated vaccine. The rabbits were administered with the RHDV vaccine in conjunction with varying concentrations of TRPPS, and their blood samples were collected at different time points to analyze the ratio and number of blood lymphocytes. In addition, sera were prepared and analyzed to determine the overall antibody titer and the level of IL-2, a cytokine commonly used as an indicator of immune activity. The various TRPPS-supplemented vaccines were shown to be more effective in enhancing the immune functions of the inoculated rabbits compared to their polysaccharide-free counterpart, with 200 mg/mL of TRPPS exhibiting the most pronounced benefits that were comparable to those of propolis. In addition, the TRPPS-supplemented RHDV inactivated vaccines could significantly improve the survival rates of the immunized rabbits against RHDV infection. Our studies offered convincing experimental evidence for the development of TRPPS as a new type of plant-derived immunopotentiator.
Assuntos
Adjuvantes Imunológicos/farmacologia , Infecções por Caliciviridae/prevenção & controle , Medicamentos de Ervas Chinesas/farmacologia , Vírus da Doença Hemorrágica de Coelhos/imunologia , Polissacarídeos/imunologia , Polissacarídeos/farmacologia , Robinia/química , Vacinas de Produtos Inativados/imunologia , Vacinas de Produtos Inativados/farmacologia , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/uso terapêutico , Animais , Anticorpos Antivirais/sangue , Infecções por Caliciviridae/imunologia , Citocinas/metabolismo , Modelos Animais de Doenças , Combinação de Medicamentos , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Imunização , Interleucina-2/análise , Linfócitos , Medicina Tradicional Chinesa , Polissacarídeos/isolamento & purificação , Polissacarídeos/uso terapêutico , Própole/farmacologia , Coelhos , Taxa de Sobrevida , Vacinação , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/uso terapêutico , Vacinas Virais/imunologia , Vacinas Virais/farmacologia , Vacinas Virais/uso terapêuticoRESUMO
The calicivirus Rabbit haemorrhagic disease virus (RHDV) is widely used in Australia as a biocontrol agent to manage wild European rabbit (Oryctolagus cuniculus) populations. However, widespread herd immunity limits the effectiveness of the currently used strain, CAPM V-351. To overcome this, we developed an experimental platform for the selection and characterisation of novel RHDV strains. As RHDV does not replicate in cell culture, variant viruses were selected by serially passaging a highly virulent RHDV field isolate in immunologically naïve laboratory rabbits that were passively immunised 18-24 hours post-challenge with a neutralising monoclonal antibody. After seven passages, two amino acid substitutions in the P2 domain of the capsid protein became fixed within the virus population. Furthermore, a synonymous substitution within the coding sequence of the viral polymerase appeared and was also maintained in all subsequent passages. These findings demonstrate proof-of-concept that RHDV evolution can be experimentally manipulated to select for virus variants with altered phenotypes, in this case partial immune escape.
Assuntos
Evolução Molecular Direcionada , Vírus da Doença Hemorrágica de Coelhos/genética , Animais , Anticorpos Monoclonais , Agentes de Controle Biológico , Infecções por Caliciviridae/virologia , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , CoelhosRESUMO
Rabbit hemorrhagic disease virus (RHDV) was released in Australia as a biocontrol agent for wild European rabbits ( Oryctolagus cuniculus ) in 1995-96; however, its effects were variable across Australia with the greatest population reductions seen in lower annual rainfall areas (<400 mm). There is speculation that the reduced effectiveness observed at higher annual rainfall sites is at least partially due to the presence of a nonpathogenic calicivirus (RCV-A1). The RCV-A1 is related to RHDV and confers partial and transient protection against lethal RHDV infection in laboratory tests. What is not well understood is where, how, and to what degree RCV-A1 impedes the effect of RHDV-mediated rabbit control under field conditions. We investigated seven wild rabbit populations across six states and territories representing different seasonal rainfall zones across Australia, four times during 2011-12, to investigate if the presence and prevalence of RCV-A1 coincided with a change in RHDV immunity status within these populations. Besides serology, tissue samples from both trapped and shot rabbits were collected for virus detection by reverse transcription PCR. Overall, 52% (n=258) of the total samples (n=496) tested positive for RHDV antibodies and 42% (n=208) positive for RCV-A1 antibodies; 30% (n=150) of the sera contained antibodies to both viruses. The proportion of rabbits with RHDV antibodies increased significantly at sites where RCV-A1 antibodies were present (χ21, α=0.1, P<0.001). Evidence that preinfection of RCV-A1 may lead to a higher proportion of sampled rabbits with antibodies to both viruses was found at only one site.
Assuntos
Infecções por Caliciviridae/veterinária , Vírus da Doença Hemorrágica de Coelhos/isolamento & purificação , Coelhos/virologia , Animais , Austrália , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Dinâmica PopulacionalRESUMO
The extremely pathogenic Rabbit haemorrhagic disease virus (RHDV) and the completely benign Rabbit calicivirus (RCV) are closely related members of the genus Lagovirus (family Caliciviridae). The molecular mechanisms that determine the dramatic difference in virulence are unknown, but indirect evidence suggests that different properties of their RNA-dependent RNA polymerases (RdRps) may at least partially be responsible for the contrasting phenotypes. Here we report that the unusual ability of the RHDV RdRp to induce a striking rearrangement of the Golgi network is not specific to RHDV, but a common feature of virulent and benign rabbit caliciviruses alike. Expression of rabbit calicivirus RdRps induced a redistribution of both cis/medial and medial/trans Golgi membrane markers, but not that of an endoplasmic reticulum membrane marker. Inactivating mutations in the conserved GDD motif did not abolish the ability of RHDV RdRp to rearrange the Golgi network, suggesting that polymerase activity and metal co-factors are not required for this function. Finally, we discuss possible implications of RdRp-induced membrane rearrangements on virus replication and host immune responses.
Assuntos
Vírus da Doença Hemorrágica de Coelhos/patogenicidade , RNA Polimerase Dependente de RNA/metabolismo , Proteínas Virais/metabolismo , Motivos de Aminoácidos , Animais , Linhagem Celular , Complexo de Golgi/virologia , Vírus da Doença Hemorrágica de Coelhos/fisiologia , RNA Polimerase Dependente de RNA/química , RNA Polimerase Dependente de RNA/genética , Coelhos , Proteínas Virais/química , Proteínas Virais/genética , Virulência/genética , Replicação ViralRESUMO
Rabbit haemorrhagic disease (RHD) is a highly lethal and contagious viral disease that produces haemorrhagic lesions in liver and lungs of domestic and wild rabbits (Oryctolagus cuniculus). This study investigates the transmission of RHDV from infected rabbits to mice, based on the detection of viral RNA. Sixteen wild mice (Mus spretus, n=12 and Apodemus sylvaticus, n=4) were put in contact with nine rabbits inoculated with RHDV. No mice died following exposure to RHDV-infected rabbits or developed macroscopic haemorrhagic lesions. On the fourth day of contact, RHDV was detected by RT-PCR in the faeces of three of the four mice killed and in the livers of two of them. Three days after contact period with the inoculated rabbits (7th day of the experiment), RHDV was detected by RT-PCR in 100% (n=4) of the faeces and 50% (n=2) of the livers of euthanized animals. Ten days after contact period (14th day of the experiment), RHDV was not detected in the faeces or liver from any of the mice euthanized. However, 64days after contact period, RHDV was detected in the faeces of one mouse (1 of 4). We demonstrate cross-species transmission of RHDV-RNA from rabbit to rodent and the capability of RHDV-RNA to persist in mice for at least 10days after contact, and potentially up to two months, although viral replication within the rodent and/or infectivity was not evaluated in the present study.
Assuntos
Infecções por Caliciviridae/transmissão , Vírus da Doença Hemorrágica de Coelhos/genética , Vírus da Doença Hemorrágica de Coelhos/patogenicidade , Animais , Infecções por Caliciviridae/veterinária , Fezes/virologia , Fígado/virologia , Camundongos , Reação em Cadeia da Polimerase , RNA Viral/análise , RNA Viral/genética , Coelhos , Especificidade da EspécieRESUMO
Rabbit hemorrhagic disease is an acute fatal highly contagious viral infectious disease that causes high losses among rabbitries. The disease was first reported in China in 1984 and later on in Saudi Arabia in 1996. The aim of this study was to investigate the emergence and pathogenicity of new rabbit hemorrhagic disease virus (RHDV) strains in Saudi Arabia. The pathogenicity was confirmed by inoculation in susceptible rabbits. Three RHDV strains were detected by reverse transcriptase polymerase chain reaction (RT-PCR) using primers targeting VP60 capsid protein gene in infected rabbitries during 2012 and 2013. These strains clustered into two genetically distinct genogroups related to year of isolation (G2 and G3). All new Saudi Arabia viruses clustered with the European strains, while the old strains clustered with strains from China and America. Based on amino acids and nucleotide sequences, the Saudi Arabia strains (RHD/1/SA/2012, RHD/2/SA/2012, and RHD/3/SA /2013) had high identity with Mexico89, Ca11-ITA, and 00-13,FRA virus; on the other hand, there was a relatively high identity with Bahrain strain. The evolutionary relationship of Saudi RHDVs strains revealed significant nucleotides and amino acid substitutions in hypervariable region E, suggesting the emergence of new RHDVs circulating in Saudi Arabia rabbitries. These antigenic changes represented by the antigenic index might be a potential cause of vaccination failure and raises the need to review the vaccination strategies against RHD.