Publications by authors named "Margarida D Duarte"

Rabbit hemorrhagic disease virus 2/genotype GI.2 (RHDV2/GI.2; , ) causes a highly contagious disease with hepatic necrosis and disseminated intravascular coagulation in several species.

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Article Synopsis
  • Bagaza virus (BAGV) is a mosquito-borne flavivirus primarily transmitted through wild birds and Culex mosquitoes, with known susceptibility in specific bird species like red-legged partridges and ring-necked pheasants.
  • In September 2023, a group of seven dead Eurasian magpies were discovered in southern Portugal, coinciding with previously found BAGV-positive birds in the same area.
  • Testing confirmed that the magpies were positive for BAGV, showing that they may serve as a new host and amplifying factor for the virus, which is actively circulating in the region.
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Avipoxvirus (APV), a linear dsDNA virus belonging to the subfamily of the family , infects more than 278 species of domestic and wild birds. It is responsible for causing avian pox disease, characterized by its cutaneous and diphtheric forms. With a high transmission capacity, it can cause high economic losses and damage to the ecosystem.

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In September 2021, Bagaza virus (BAGV), a member of the Ntaya group from the genus, was detected for the first time in Portugal, in the heart and the brain of a red-legged partridge found dead in a hunting ground in Serpa (Alentejo region; southern Portugal). Here we report the genomic characterization of the full-length sequence of the BAGV detected (BAGV/PT/2021), including phylogenetic reconstructions and spaciotemporal analyses. Phylogenies inferred from nucleotide sequence alignments, complemented with the analysis of amino acid alignments, indicated that the BAGV strain from Portugal is closely related to BAGV strains previously detected in Spain, suggesting a common ancestor that seems to have arrived in the Iberia Peninsula in the late 1990s to early 2000s.

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Bagaza virus emerged in Spain in 2010 and was not reported in other countries in Europe until 2021, when the virus was detected by molecular methods in a corn bunting and several red-legged partridges in Portugal. Sequencing revealed high similarity between the 2021 strains from Portugal and the 2010 strains from Spain.

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Myxomatosis is an emergent disease in the Iberian hare (Lepus granatensis). In this species, the disease is caused by a natural recombinant virus (ha-myxoma virus [MYXV]) identified for the first time in 2018 and has since been responsible for a large number of outbreaks in Spain and Portugal. The ha-MYXV, which harbours a 2.

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The recent emergence of a new myxoma virus capable of causing disease in the Iberian hare () has resulted in numerous outbreaks with high mortality leading to the reduction, or even the disappearance, of many local populations of this wild species in the Iberian Peninsula. Currently, the available vaccines that prevent myxomatosis in domestic rabbits caused by classic strains of myxoma virus have not been assessed for use in Iberian hares. The main objective of this study was to evaluate the efficacy of commercial rabbit vaccines in Iberian hares and wild rabbits against the natural recombinant myxoma virus (ha-MYXV), bearing in mind its application in specific scenarios where capture is possible, such as genetic reserves.

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It is unclear whether West Nile virus (WNV) circulates endemically in Portugal. Despite the country's adequate climate for transmission, Portugal has only reported four human WNV infections so far. We performed a review of WNV-related data (1966-2020), explored mosquito (2016-2019) and land type distributions (1992-2019), and used climate data (1981-2019) to estimate WNV transmission suitability in Portugal.

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A natural recombinant myxoma virus (referred to as ha-MYXV or MYXV-Tol08/18) emerged in the Iberian hare () and the European rabbit () 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 gene that disrupted it into ORFs and .

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Commercial hare and rabbit immortalized cell lines are extremely limited regarding the many species within the lagomorpha order. To overcome this limitation, researchers and technicians must establish primary cell cultures derived from biopsies or embryos. Among all cell types, fibroblasts are plastic and resilient cells, highly convenient for clinical and fundamental research but also for diagnosis, particularly for viral isolation.

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Molecular methods, established in the 1980s, expanded and delivered tools for the detection of vestigial quantities of nucleic acids in biological samples. Nucleotide sequencing of these molecules reveals the identity of the organism it belongs to. However, the implications of such detection are often misinterpreted as pathogenic, even in the absence of corroborating clinical evidence.

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In late 2019, the first herpesvirus in the genus Lepus, named leporid gammaherpesvirus 5 (LeHV-5) was described. At the time, herpetic typical lesions were observed in hares infected by the myxoma virus, which is known to induce immunosuppression. Though the real impact of LeHV-5 is still poorly understood, since it affects reproduction, it poses an additional threat to the already fragile populations of Iberian hare, demanding prevalence investigations.

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Rabbit haemorrhagic disease (RHD) is a major threat to domestic and wild European rabbits. Presently, in Europe, the disease is caused mainly by Rabbit haemorrhagic disease virus 2 (RHDV2/b or Lagovirus europaeus GI.2), the origin of which is still unclear, as no RHDV2 reservoir hosts were identified.

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Rabbit haemorrhagic disease (RHD) is a highly contagious infectious disease of European wild and domestic rabbits. Rabbit haemorrhagic disease virus (RHDV, GI.1) emerged in 1986 in Europe, rapidly spreading all over the world.

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Article Synopsis
  • Myxomatosis has emerged as a disease in Iberian hares, previously thought to only affect rabbits, with distinct genomic features traced back to a recombinant virus discovered in 2019.
  • Unlike traditional myxoma virus strains in rabbits, the new hare myxoma virus (ha-MYXV) contains a 2.8 kb genomic region that alters its function, raising concerns about species segregation between hares and rabbits.
  • Recent cases in unvaccinated European rabbits showed high mortality linked to the recombinant virus, underscoring the need to reassess vaccine effectiveness for both hares and rabbits in response to this emerging threat.
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Article Synopsis
  • In late 2018, a myxomatosis outbreak in the Iberian Peninsula caused significant deaths in Iberian hare populations due to a recombinant Myxoma virus identified with specific genetic changes.
  • Researchers tested over 1,600 rabbits and 125 hares, finding that while the standard Myxoma virus was present in rabbits, the recombinant version was affecting hares.
  • Recent findings of dead wild rabbits in Portugal, showing severe symptoms and positive test results for the recombinant virus, underscore the potential threat to Iberian wildlife and highlight the necessity for ongoing monitoring of these viral strains in both rabbits and hares.
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We report the detection of rabbit haemorrhagic disease virus 2 (RHDV2) in the Madeira archipelago, Portugal. Viral circulation was confirmed by RT-qPCR and vp60 sequencing. Epidemiological data revealed the outbreak initiated in October 2016 in Porto Santo affecting wild and domestic rabbits.

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Molecular methods are fundamental tools for the diagnosis of viral infections. While interpretation of results is straightforward for unvaccinated animals, where positivity represents ongoing or past infections, the presence of vaccine virus in the tissues of recently vaccinated animals may mislead diagnosis. In this study, we investigated the interference of RHDV2 vaccination in the results of a RT-qPCR for RHDV2 detection, and possible associations between mean Cq values of five animal groups differing in age, vaccination status and origin (domestic/wild).

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A specific real time RT-PCR for the detection of RHDV2 was developed and validated using RHDV and RHDV2 RNA preparations from positive field samples. The system was designed to amplify a 127 nucleotide-long RNA region located within the vp60 gene, based on the alignment of six sequences originated in Portugal, obtained in our laboratory, and 11 sequences from France and Italy. The primers and probe target sequences are highly conserved in the vast majority of the RHDV2 sequences presently known.

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The genetic relationships between 10 rabbit hemorrhagic disease strains collected in Portugal between 2006 and 2013, originated in the mainland and Azorean islands, were investigated based on the vp60 gene variability. A genetic diversity ranging from 2% to 13% was determined among the 10-vp60 complete sequences revealing a significant level of genetic heterogeneity between same strains. Phylogenetic Bayesian analysis showed that the Portuguese RHDV strains fell within different genogroups, namely G1, G5 and G6.

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The myxoma virus (MYXV) causes severe infections in European rabbits that may reach mortality rates up to 100% depending on the viral strain. The typical symptoms and lesions induced by the virus are usually enough to permit the correct clinical diagnosis. However, in peracute forms the infection may be accompanied by unspecific symptoms.

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The exposure of wild carnivores to viral pathogens, with emphasis on parvovirus (CPV/FPLV), was assessed based on the molecular screening of tissue samples from 128 hunted or accidentally road-killed animals collected in Portugal from 2008 to 2011, including Egyptian mongoose (Herpestes ichneumon, n = 99), red fox (Vulpes vulpes, n = 19), stone marten (Martes foina, n = 3), common genet (Genetta genetta, n = 3) and Eurasian badger (Meles meles, n = 4). A high prevalence of parvovirus DNA (63%) was detected among all surveyed species, particularly in mongooses (58%) and red foxes (79%), along with the presence of CPV/FPLV circulating antibodies that were identified in 90% of a subset of parvovirus-DNA positive samples. Most specimens were extensively autolysed, restricting macro and microscopic investigations for lesion evaluation.

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Two cases of fatal infection caused by parvovirus in a white tiger (Panthera tigris) and an African lion (Panthera leo) at the Lisbon Zoo (Portugal) are described. Gross findings at necropsy were catharral enteritis in the tiger and severe hemorrhagic enteritis in the lion. Histopathologic examination revealed, in both animals, intestinal crypt necrosis and lymphocyte depletion in the germinal centers of the mesenteric lymph nodes.

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