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Detection and phylogenetic analysis of tick-borne viruses circulating in Portugal and Poland
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As carraças são vetores de diversos agentes infecciosos, incluindo o notório vírus da encefalite
transmitida por carraças (TBEV), o vírus Heartland (HRTV), membro da família Phenuiviridae, e os
recentemente descobertos jingmenvírus, como o vírus Jingmen (JMTV) e o vírus Alongshan (ALSV).
A vigilância epidemiológica molecular é crucial não só para compreender a diversidade dos vírus
circulantes, mas também no que toca à prevenção e contenção de surtos. Uma vez que os estudos que
caracterizam o viroma das carraças de Portugal são escassos, o objetivo deste projeto consiste em
rastrear carraças colhidas em Portugal para a deteção de jingmenvírus e flebovírus, concluíndo com a
análise filogenética das sequências resultantes. Um protocolo de RT-PCR dedicado e primers
desenhados internamente foram utilizados nos ensaios para a detecção de jingmenvírus.
Adicionalmente, extratos previamente disponibilizados de cDNA de carraças da Polónia foram
rastreados para flebo- e jingmenvírus, assim como flavivírus. Os resultados mostraram que os
flebovírus, particularmente os da linhagem AnLuc, circulam com uma prevalência elevada de 29% (10
pools positivos em 35) em carraças Rhipicephalus bursa das regiões de Lisboa e Alentejo de Portugal,
de acordo com estudos anteriores realizados no Instituto de Higiene e Medicina Tropical (IHMT). O
vírus Uukuniemi (UUKV) foi ainda detetado com uma prevalência surpreendentemente alta de 12%
(quatro pools positivos em 34) em Ixodes ricinus da província de Warmińsko-Mazurskie na Polónia, o
que sugere que o UUKV é altamente endémico nessa região. As sequências nucleotídicas partilham
98,7% de identidade com sequências de UUKV isoladas entre 1963 e 2004, o que demonstra que o
UUKV tem um genoma de RNA particularmente estável. Não foram detetados jingmenvírus ou
flavivírus nos espécimes de ambos os países, o que pode refletir a baixa diversidade espacial, temporal
e taxonómica das amostras de carraças rastreadas, limitações inerentes à abordagem de amplificação
com primers específicos ou, eventualmente, baixa prevalência ou, simplesmente, ausência destes
grupos virais nas regiões investigadas.
Ticks are vectors of many infectious agents, including the notorious tick-borne encephalitis flavivirus (TBEV), the Phenuiviridae member Heartland virus (HRTV), and novel flavi-like viruses of the Jingmen group, such as Jingmen tick virus (JMTV) and Alongshan virus (ALSV). Molecular epidemiology surveys are important not only to gain a good understanding of the diversity of circulating viruses, but also in outbreak prevention and preparedness. Since the virome of ticks from Portugal remains poorly understood, this study aimed to screen ticks collected in Portugal for flavi-like viruses and phleboviruses, the latter known to circulate in the country, and use phylogenetic tools to analyse the resulting sequences. A dedicated nested RT-PCR protocol and in-house designed primers were used in assays for the detection of Jingmen group viruses. In addition, available cDNA extracts of ticks from Poland were also surveyed for phlebo- and jingmenviruses, as well as flaviviruses. Results showed that phleboviruses, particularly those of the AnLuc lineage, circulate with a high prevalence of 29% (10 positives in 35 pools) in Rhipicephalus bursa questing ticks from the Lisboa and Alentejo regions of Portugal, in accordance with previous studies carried out at Instituto de Higiene e Medicina Tropical (IHMT). Additionally, the Uukuniemi virus (UUKV) was detected with a surprisingly high prevalence of 12% (four positives in 34 pools) in Ixodes ricinus from the Warmińsko-Mazurskie province in Poland, suggesting that UUKV is highly endemic to this area. Sequences shared 98.7% nucleotide identity with UUKV strains isolated between 1963 and 2004, which demonstrates that UUKV has a remarkably stable RNA genome. No jingmenviruses or flaviviruses were detected in the specimens from either country, which could reflect the low spatial, temporal, and taxonomic diversity of the tick samples surveyed, limitations inherent to the targeted approach or, eventually, low prevalence or, simply, absence of these viral groups in these regions.
Ticks are vectors of many infectious agents, including the notorious tick-borne encephalitis flavivirus (TBEV), the Phenuiviridae member Heartland virus (HRTV), and novel flavi-like viruses of the Jingmen group, such as Jingmen tick virus (JMTV) and Alongshan virus (ALSV). Molecular epidemiology surveys are important not only to gain a good understanding of the diversity of circulating viruses, but also in outbreak prevention and preparedness. Since the virome of ticks from Portugal remains poorly understood, this study aimed to screen ticks collected in Portugal for flavi-like viruses and phleboviruses, the latter known to circulate in the country, and use phylogenetic tools to analyse the resulting sequences. A dedicated nested RT-PCR protocol and in-house designed primers were used in assays for the detection of Jingmen group viruses. In addition, available cDNA extracts of ticks from Poland were also surveyed for phlebo- and jingmenviruses, as well as flaviviruses. Results showed that phleboviruses, particularly those of the AnLuc lineage, circulate with a high prevalence of 29% (10 positives in 35 pools) in Rhipicephalus bursa questing ticks from the Lisboa and Alentejo regions of Portugal, in accordance with previous studies carried out at Instituto de Higiene e Medicina Tropical (IHMT). Additionally, the Uukuniemi virus (UUKV) was detected with a surprisingly high prevalence of 12% (four positives in 34 pools) in Ixodes ricinus from the Warmińsko-Mazurskie province in Poland, suggesting that UUKV is highly endemic to this area. Sequences shared 98.7% nucleotide identity with UUKV strains isolated between 1963 and 2004, which demonstrates that UUKV has a remarkably stable RNA genome. No jingmenviruses or flaviviruses were detected in the specimens from either country, which could reflect the low spatial, temporal, and taxonomic diversity of the tick samples surveyed, limitations inherent to the targeted approach or, eventually, low prevalence or, simply, absence of these viral groups in these regions.
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Palavras-chave
Microbiologia médica Carraças Agentes infecciosos Ixódídios Flavivírus Análise filogenética Rastreio epidemiológico