scholarly journals Detection of Recombinant Hare Myxoma Virus in Wild Rabbits (Oryctolagus cuniculus algirus)

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1127
Author(s):  
Fábio A. Abade dos Santos ◽  
Carina L. Carvalho ◽  
Andreia Pinto ◽  
Ranjit Rai ◽  
Madalena Monteiro ◽  
...  
Keyword(s):  
Myxoma Virus ◽  
Virus Infectivity ◽  
Sequencing Analysis ◽  
Wild Rabbit ◽  
Mainland Portugal ◽  
Viral Particles ◽  
Domestic Rabbits ◽  
Virus Strains ◽  
Iberian Hare ◽  
Species Segregation

In late 2018, an epidemic myxomatosis outbreak emerged on the Iberian Peninsula leading to high mortality in Iberian hare populations. A recombinant Myxoma virus (strains MYXV-Tol and ha-MYXV) was rapidly identified, harbouring a 2.8 kbp insertion containing evolved duplicates of M060L, M061L, M064L, and M065L genes from myxoma virus (MYXV) or other Poxviruses. Since 2017, 1616 rabbits and 125 hares were tested by a qPCR directed to M000.5L/R gene, conserved in MYXV and MYXV-Tol/ha-MYXV strains. A subset of the positive samples (20%) from both species was tested for the insert with MYXV being detected in rabbits and the recombinant MYXV in hares. Recently, three wild rabbits were found dead South of mainland Portugal, showing skin oedema and pulmonary lesions that tested positive for the 2.8 kbp insert. Sequencing analysis showed 100% similarity with the insert sequences described in Iberian hares from Spain. Viral particles were observed in the lungs and eyelids of rabbits by electron microscopy, and isolation in RK13 cells attested virus infectivity. Despite that the analysis of complete genomes may predict the recombinant MYXV strains’ ability to infect rabbit, routine analyses showed species segregation for the circulation of MYXV and recombinant MYXV in wild rabbit and in Iberian hares, respectively. This study demonstrates, however, that recombinant MYXV can effectively infect and cause myxomatosis in wild rabbits and domestic rabbits, raising serious concerns for the future of the Iberian wild leporids while emphasises the need for the continuous monitoring of MYXV and recombinant MYXV in both species.

scholarly journals Detection of Recombinant Hare Myxoma Virus in Wild Rabbits (Oryctolagus cuniculus algirus)

2020 ◽  
Author(s):  
Fábio A. Abade dos Santos ◽  
Carina L. Carvalho ◽  
Andreia Pinto ◽  
Ranjit Rai ◽  
Madalena Monteiro ◽  
...  
Keyword(s):  
Myxoma Virus ◽  
Virus Infectivity ◽  
Wild Rabbit ◽  
R Gene ◽  
Viral Particles ◽  
Domestic Rabbits ◽  
South Portugal ◽  
Iberian Hare ◽  
Continue Monitoring ◽  
Species Segregation

In late 2018, an epidemic myxomatosis outbreak emerged on the Iberian Peninsula leading to high mortality in Iberian hare populations. Soon, a recombinant virus (MYXV-Tol or ha-MYXV) was identified, harboring a 2.8 kb insertion containing evolved duplicates of M060L, M061L, M064L, and M065L from MYXV. Since 2017, 1616 rabbits and 82 hares were tested by a qPCR directed to M000.5L/R gene, conserved in MYXV and MYXV-Tol/ ha-MYXV strains. A subset (20%) of the positive samples was tested for the insert with MYXV being detected in rabbits and recombinant MYXV in hares. Recently, two wild rabbits found dead in South Portugal, showing skin oedema and pulmonary lesions tested positive for the 2.8 Kb insert. Sequencing showed 100% similarity with the insert sequences described in Iberian hares from Spain. Viral particles were observed in the lungs of both rabbits by electron microscopy, and isolation in RK13 cells showed virus infectivity. Despite the analysis of recombinant MYXV genomes may predict its ability to infect rabbit, routine analyses showed species segregation for the circulation of MYXV and recombinant MYXV in wild rabbit and in Iberian hares, respectively. This study demonstrates, however, that recombinant MYXV can effectively infect and cause myxomatosis in wild rabbits and domestic rabbits, which raises serious concerns for the future of the Iberian wild leporids and emphasizes the need to continue monitoring MYXV and recombinant MYXV in both species.

scholarly journals A Quadruplex qPCR for Detection and Differentiation of Classic and Natural Recombinant Myxoma Virus Strains of Leporids

2021 ◽  
Vol 22 (21) ◽  
pp. 12052
Author(s):  
Fábio A. Abade dos Santos ◽  
Carina L. Carvalho ◽  
Francisco Parra ◽  
Kevin P. Dalton ◽  
Maria C. Peleteiro ◽  
...  
Keyword(s):  
Real Time ◽  
Housekeeping Gene ◽  
Myxoma Virus ◽  
European Rabbit ◽  
Fast Method ◽  
Wild Rabbit ◽  
Viral Dna ◽  
Eukaryotic Organisms ◽  
Virus Strains ◽  
Iberian Hare

A natural recombinant myxoma virus (referred to as ha-MYXV or MYXV-Tol08/18) emerged in the Iberian hare (Lepus granatensis) and the European rabbit (Oryctolagus cuniculus) in late 2018 and mid-2020, respectively. This new virus is genetically distinct from classic myxoma virus (MYXV) strains that caused myxomatosis in rabbits until then, by acquiring an additional 2.8 Kbp insert within the m009L gene that disrupted it into ORFs m009L-a and m009L-b. To distinguish ha-MYXV from classic MYXV strains, we developed a robust qPCR multiplex technique that combines the amplification of the m000.5L/R duplicated gene, conserved in all myxoma virus strains including ha-MYXV, with the amplification of two other genes targeted by the real-time PCR systems designed during this study, specific either for classic MYXV or ha-MYXV strains. The first system targets the boundaries between ORFs m009L-a and m009L-b, only contiguous in classic strains, while the second amplifies a fragment within gene m060L, only present in recombinant MYXV strains. All amplification reactions were validated and normalized by a fourth PCR system directed to a housekeeping gene (18S rRNA) conserved in eukaryotic organisms, including hares and rabbits. The multiplex PCR (mPCR) technique described here was optimized for Taqman® and Evagreen® systems allowing the detection of as few as nine copies of viral DNA in the sample with an efficiency > 93%. This real-time multiplex is the first fast method available for the differential diagnosis between classic and recombinant MYXV strains, also allowing the detection of co-infections. The system proves to be an essential and effective tool for monitoring the geographical spread of ha-MYXV in the hare and wild rabbit populations, supporting the management of both species in the field.

scholarly journals Changes in the virulence of myxoma virus strains in Britain

1987 ◽  
Vol 98 (1) ◽  
pp. 113-117 ◽  
Author(s):  
J. Ross ◽  
M. F. Sanders
Keyword(s):  
Myxoma Virus ◽  
Wild Rabbit ◽  
National Surveys ◽  
Testing Method ◽  
Development Of Resistance ◽  
Similar Survey ◽  
Virus Strains

SUMMARYNational surveys of the virulence of field strains of myxoma virus were carried out in 1975 (128 virus strains) and in 1981 (123 strains), using the virulence testing method employed in a similar survey in 1962. Results showed that the virulence of field strains had increased between 1962 and 1975, and again between 1975 and 1981. The increases in virulence are thought to be a result of the development of resistance to myxomatosis in wild rabbit populations. The effects of the changes in virulence and resistance are discussed.

scholarly journals First description of a herpesvirus infection in genus Lepus

2020 ◽  
Author(s):  
F.A. Abade dos Santos ◽  
M. Monteiro ◽  
A. Pinto ◽  
C.L. Carvalho ◽  
M.C. Peleteiro ◽  
...  
Keyword(s):  
Stromal Cells ◽  
Inclusion Bodies ◽  
International Committee ◽  
Myxoma Virus ◽  
Sequencing Analysis ◽  
Wild Populations ◽  
Herpesvirus Infection ◽  
Transmission Electron ◽  
The Impact ◽  
Iberian Hare

AbstractDuring the necropsies of Iberian hares obtained in 2018/2019, along with signs of the nodular form of myxomatosis, other unexpected external lesions were also observed. Histopathology revealed nuclear inclusion bodies in stromal cells suggesting the additional presence of a nuclear replicating virus.Transmission electron microscopy further demonstrated the presence of herpesvirus particles in the tissues of affected hares.We confirmed the presence of herpesvirus in 13 MYXV-positive hares by PCR and sequencing analysis. Herpesvirus-DNA was also detected in seven healthy hares, suggesting its asymptomatic circulation.Phylogenetic analysis based on DNA polymerase gene, grouped this virus within the gammaherpesviruses, close to herpesviruses from bats and rodents.We propose to name this new virus Leporid gammaherpesvirus 5 (LeHV-5), according to the International Committee on Taxonomy of Viruses standards.The impact of herpesvirus infection on the reproduction and mortality of the Iberian hare is yet unknown but may aggravate the decline of wild populations caused by the recently emerged natural recombinant myxoma virus.

scholarly journals Genetic characterization of a recombinant myxoma virus leap into the Iberian hare (Lepus granatensis)

2019 ◽  
Author(s):  
Ana Águeda-Pinto ◽  
Ana Lemos de Matos ◽  
Mário Abrantes ◽  
Simona Kraberger ◽  
Maria A. Risalde ◽  
...  
Keyword(s):  
Myxoma Virus ◽  
Open Reading Frames ◽  
Lepus Europaeus ◽  
European Rabbit ◽  
New Host ◽  
Tissue Samples ◽  
Lepus Granatensis ◽  
Domestic Rabbits ◽  
Iberian Hare

AbstractMyxomatosis is a lethal disease of wild European and domestic rabbits (Oryctolagus cuniculus) caused by a Myxoma virus (MYXV) infection, a leporipoxvirus that is found naturally in someSylvilagusrabbit species in South America and California. The introduction of MYXV in the early 1950s into feral European rabbit populations in Australia and Europe demonstrate the best documented field example of host-virus coevolution following a cross-species transmission. Recently, a new cross-species jump of MYXV has been suggested in both Great Britain and Spain, where European brown hares (Lepus europaeus) and Iberian hares (Lepus granatensis) were found dead with lesions consistent with those observed in myxomatosis. To investigate the possibility of a new cross-species transmission event by MYXV, tissue samples collected from a wild Iberian hare found dead in Spain (Toledo region) were analyzed and deep sequenced. Our results report a new MYXV strain (MYXV Toledo) in the tissues of this species. The genome of this new strain encodes three disrupted genes (M009L,M036LandM152R) and a novel 2.8 KB recombinant region that resulted from an insertion of four novel poxviral genes towards the 5’ end of its genome. From the open reading frames inserted into the MYXV Toledo strain, a new orthologue of a poxvirus host range gene family member was identified which is related to the MYXV geneM064R. Overall, we confirmed the identity of a new MYXV strain in Iberian hares that we hypothesize was able to more effectively counteract the host defenses in hares and start an infectious process in this new host.

scholarly journals Genetic Characterization of a Recombinant Myxoma Virus in the Iberian Hare (Lepus granatensis)

Viruses ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 530 ◽  
Author(s):  
Ana Águeda-Pinto ◽  
Ana Lemos de Matos ◽  
Mário Abrantes ◽  
Simona Kraberger ◽  
Maria A. Risalde ◽  
...  
Keyword(s):  
Myxoma Virus ◽  
Open Reading Frames ◽  
Lepus Europaeus ◽  
European Rabbit ◽  
New Host ◽  
Tissue Samples ◽  
Lepus Granatensis ◽  
Domestic Rabbits ◽  
Iberian Hare

Myxomatosis is a lethal disease in wild European and domestic rabbits (Oryctolagus cuniculus), which is caused by a Myxoma virus (MYXV) infection—a leporipoxvirus that is found naturally in some Sylvilagus rabbit species in South America and California. The introduction of MYXV into feral European rabbit populations of Australia and Europe, in the early 1950s, demonstrated the best-documented field example of host–virus coevolution, following a cross-species transmission. Recently, a new cross-species jump of MYXV has been suggested in both Great Britain and Spain, where European brown hares (Lepus europaeus) and Iberian hares (Lepus granatensis) were found dead with lesions consistent with those observed in myxomatosis. To investigate the possibility of a new cross-species transmission event by MYXV, tissue samples collected from a wild Iberian hare found dead in Spain (Toledo region) were analyzed and deep sequenced. Our results reported a new MYXV isolate (MYXV Toledo) in the tissues of this species. The genome of this new virus was found to encode three disruptive genes (M009L, M036L, and M152R) and a novel ~2.8 kb recombinant region, which resulted from an insertion of four novel poxviral genes towards the 3’ end of the negative strand of its genome. From the open reading frames inserted into the MYXV Toledo virus, a new orthologue of a poxvirus host range gene family member was identified, which was related to the MYXV gene M064R. Overall, we confirmed the identity of a new MYXV isolate in Iberian hares, which, we hypothesized, was able to more effectively counteract the host defenses in hares and start an infectious process in this new host.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

scholarly journals Myxomatosis in farmland rabbit populations in England and Wales

1989 ◽  
Vol 103 (2) ◽  
pp. 333-357 ◽  
Author(s):  
J. Ross ◽  
A. M. Tittensor ◽  
A. P. Fox ◽  
M. F. Sanders
Keyword(s):  
Breeding Season ◽  
Annual Cycle ◽  
Seasonal Pattern ◽  
Mortality Factor ◽  
Mass Movements ◽  
Wild Rabbit ◽  
Regulatory Effect ◽  
Methods Of Calculation ◽  
Attenuated Virus ◽  
Virus Strains

SUMMARYThe overall pattern and consequences of myxomatosis in wild rabbit populations were studied at three farmland sites in lowland southern England and upland central Wales between 1971 and 1978. When results from all years were combined, the disease showed a clear two-peaked annual cycle, with a main autumn peak between August and January, and a subsidiary spring peak during February to April.Rabbit fleas, the main vectors of myxomatosis in Britain, were present on full-grown rabbits in sufficient numbers for transmission to occur throughout the year, but the observed seasonal pattern of the disease appeared to be influenced by seasonal mass movements of these fleas. However other factors were also important including the timing and success of the main rabbit breeding season, the proportion of rabbits which had recovered from the disease and the timing and extent of autumn rabbit mortality from other causes.Significantly more males than females, and more adults and immatures than juveniles, were observed to be infected by myxomatosis. Only 25–27% of the total populations were seen to be infected during outbreaks. Using two independent methods of calculation, it was estimated that between 47 and 69% of infected rabbits died from the disease (much lower than the expected 90–95% for fully susceptible rabbits with the partly attenuated virus strains that predominated). Thus it was estimated that 12–19% of the total rabbit populations were known to have died directly or indirectly from myxomatosis.Although the effects of myxomatosis were much less than during the 1950s and 1960s, it continued to be an important mortality factor. It may still have a regulatory effect on rabbit numbers, with autumn/winter peaks of disease reducing the numbers of rabbits present at the start of the breeding season.

scholarly journals Phosphatidylserine within the Viral Membrane Enhances Chikungunya Virus Infectivity in a Cell-type Dependent Manner

2022 ◽  
Author(s):  
Kerri L Miazgowicz ◽  
Judith Mary Reyes Ballista ◽  
Marissa D Acciani ◽  
Ariana R Jimenez ◽  
Ryan S Belloli ◽  
...  
Keyword(s):  
Chikungunya Virus ◽  
Intervention Strategy ◽  
Host Cells ◽  
Virus Infectivity ◽  
Dependent Manner ◽  
Cell Type ◽  
Enveloped Viruses ◽  
Outer Leaflet ◽  
Viral Particles ◽  
In Cells

Chikungunya virus (CHIKV), an alphavirus of the Togaviridae family, is the causative agent of the human disease chikungunya fever (CHIKF), which is characterized by debilitating acute and chronic arthralgia. No licensed vaccines or antivirals exist for CHIKV. Preventing the attachment of viral particles to host cells is an attractive intervention strategy. Viral entry of enveloped viruses from diverse families including Filoviridae and Flaviviridae is mediated or enhanced by phosphatidylserine receptors (PSRs). PSRs facilitate the attachment of enveloped viruses to cells by binding to exposed phosphatidylserine (PS) in the viral lipid membrane - a process termed viral apoptotic mimicry. To investigate the role of viral apoptotic mimicry during CHIKV infection, we produced viral particles with discrete amounts of exposed PS on the virion envelope by exploiting the cellular distribution of phospholipids at the plasma membrane. We found that CHIKV particles containing high outer leaflet PS (produced in cells lacking flippase activity) were more infectious in Vero cells than particles containing low levels of outer leaflet PS (produced in cells lacking scramblase activity). However, the same viral particles were similarly infectious in NIH3T3 and HAP1 cells, suggesting PS levels can influence infectivity only in cells with high levels of PSRs. Interestingly, PS-dependent CHIKV entry was observed in mosquito Aag2 cells, but not C6/36 cells. These data demonstrate that CHIKV entry via viral apoptotic mimicry is cell-type dependent. Furthermore, viral apoptotic mimicry has a mechanistic basis to influence viral dynamics in vivo in both the human and mosquito host.

scholarly journals Myxomatosis in the Mallee region of Victoria, Australia

1978 ◽  
Vol 81 (2) ◽  
pp. 239-243 ◽  
Author(s):  
Rosamond C. H. Shepherd ◽  
J. W. Edmonds ◽  
I. F. Nolan ◽  
A. Gocs
Keyword(s):  
Late Summer ◽  
Nutritional Stress ◽  
Early Summer ◽  
Myxoma Virus ◽  
Direct Result ◽  
Healthy Population ◽  
Wild Rabbit ◽  
Population Reduction ◽  
In The Wild ◽  
Limited Food

SummarySharp reductions in the wild rabbit (Oryctolagus cuniculus (L.)) population in the Mallee are associated with annual myxomatosis epizootics. The extent to which the population reductionsare the direct result of the epizootics varies with time of epizootic occurrence. All grazing animals in the Mallee are under nutritional stress each summer and autumn. When the epizootic occurs during the early summer heavy losses occur in a previously healthy population. Similar losses which occur in the late summer and autumn are the result of a nutritional stress – epizootic complex. The end result in each case is a population reduction of about 80%.This reduction occurs in a population which is the most resistant to myxomatosis known in Victoria and in association with epizooties caused by field strains of myxoma virus of moderate virulence only.The earlier summer epizootics are of considerable economic importance because they sharply reduce the pressure on the limited food available for other grazing animals.

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