The known unknowns of Powassan virus ecology

Brackney, Doug E; Vogels, Chantal B F

doi:10.1093/jme/tjad095

Cited by 3 publications

(5 citation statements)

References 81 publications

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“…The mechanisms behind the focality of DTV transmission cycles in Massachusetts and the surrounding northeast states remain poorly understood [ 16 ]. The variation in site-specific infection prevalence (0–10.4%) on a relatively small scale observed in our survey of host-seeking ticks may be partially attributed to the limited sampling power and scale inherent in active surveillance efforts.…”

Section: Discussionmentioning

confidence: 99%

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Active Surveillance of Powassan Virus in Massachusetts Ixodes scapularis Ticks, Comparing Detection Using a New Triplex Real-Time PCR Assay with a Luminex Vector-Borne Panel

Xu,

Siegel,

Fernandez

et al. 2024

Viruses

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Powassan virus is an emerging tick-borne pathogen capable of causing severe neuroinvasive disease. As the incidence of human Powassan virus grows both in magnitude and geographical range, the development of sensitive detection methods for diagnostics and surveillance is critical. In this study, a Taqman-based triplex real-time PCR assay was developed for the simultaneous and quantitative detection of Powassan virus and Powassan virus lineage II (deer tick virus) in Ixodes scapularis ticks. An exon–exon junction internal control was built-in to allow for accurate detection of RNA quality and the failure of RNA extraction. The newly developed assay was also applied to survey deer tick virus in tick populations at 13 sites on Cape Cod and Martha’s Vineyard Island in Massachusetts. The assay’s performance was compared with the Luminex xMAP MultiFLEX Vector-borne Panel 2. The results suggested that the real-time PCR method was more sensitive. Powassan virus infection rates among ticks collected from these highly endemic tick areas ranged from 0.0 to 10.4%, highlighting the fine-scale geographic variations in deer tick virus presence in this region. Looking forward, our PCR assay could be adopted in other Powassan virus surveillance systems.

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Section: Discussionmentioning

confidence: 99%

“…Shrews ( Sorex spp. ; Blarina brevicauda ) have recently been implicated as reservoir hosts for DTV, and many unknowns still exist around DTV ecological maintenance and amplification [ 15 , 16 ]. Deer Tick Virus is considered a greater public health threat due to the opportunistic nature of I. scapularis [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Active Surveillance of Powassan Virus in Massachusetts Ixodes scapularis Ticks, Comparing Detection Using a New Triplex Real-Time PCR Assay with a Luminex Vector-Borne Panel

Xu,

Siegel,

Fernandez

et al. 2024

Viruses

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“…Furthermore, recent laboratory studies demonstrate that D. variabilis , H. longicornis and Amblyomma americanum are competent vectors for POWV II [ 23 , 24 ]. These findings suggest that the transmission cycles of POWV I and POWV II could be more complex than the single tick vector species/single reservoir host paradigm [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

“…Prior to this work by Jones et al., it was believed that an obvious viremia and systemic infection was necessary for ticks to acquire virus during blood feeding; however, Jones’ work was paradigm shifting in that it demonstrated that tick-to-tick transmission of virus can occur via nonviremic hosts. To date, no reservoir host has been clearly defined for POWV II; therefore, it is possible that POWV II may be sustained in natural transmission cycles via nonviremic transmission between co-feeding ticks [ 39 ], as has been shown for tick-borne encephalitis virus (TBEV) transmission in Europe [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Interspecies co-feeding transmission of Powassan virus between a native tick, Ixodes scapularis, and the invasive East Asian tick, Haemaphysalis longicornis

Obellianne,

Norman,

Esteves

et al. 2024

Parasites Vectors

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Background Powassan virus, a North American tick-borne flavivirus, can cause severe neuroinvasive disease in humans. While Ixodes scapularis are the primary vectors of Powassan virus lineage II (POWV II), also known as deer tick virus, recent laboratory vector competence studies showed that other genera of ticks can horizontally and vertically transmit POWV II. One such tick is the Haemaphysalis longicornis, an invasive species from East Asia that recently established populations in the eastern USA and already shares overlapping geographic range with native vector species such as I. scapularis. Reports of invasive H. longicornis feeding concurrently with native I. scapularis on multiple sampled hosts highlight the potential for interspecies co-feeding transmission of POWV II. Given the absence of a clearly defined vertebrate reservoir host for POWV II, it is possible that this virus is sustained in transmission foci via nonviremic transmission between ticks co-feeding on the same vertebrate host. The objective of this study was to evaluate whether uninfected H. longicornis co-feeding in close proximity to POWV II-infected I. scapularis can acquire POWV independent of host viremia. Methods Using an in vivo tick transmission model, I. scapularis females infected with POWV II (“donors”) were co-fed on mice with uninfected H. longicornis larvae and nymphs (“recipients”). The donor and recipient ticks were infested on mice in various sequences, and mouse infection status was monitored by temporal screening of blood for POWV II RNA via quantitative reverse transcription polymerase chain reaction (q-RT-PCR). Results The prevalence of POWV II RNA was highest in recipient H. longicornis that fed on viremic mice. However, nonviremic mice were also able to support co-feeding transmission of POWV, as demonstrated by the detection of viral RNA in multiple H. longicornis dispersed across different mice. Detection of viral RNA at the skin site of tick feeding but not at distal skin sites indicates that a localized skin infection facilitates transmission of POWV between donor and recipient ticks co-feeding in close proximity. Conclusions This is the first report examining transmission of POWV between co-feeding ticks. Against the backdrop of multiple unknowns related to POWV ecology, findings from this study provide insight on possible mechanisms by which POWV could be maintained in nature. Graphical Abstract

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“…Multiple phylogeographic analyses of POWV genomes suggest that the virus exists in discrete transmission foci with infrequent dispersal between enzootic sites [ 15 , 16 ]. Such isolation could imply adaptation to local transmission conditions such as host or vector diversity and genetic background, as well as extrinsic influences such as microclimate [ 17 ]. Indeed, geographic risk of human POWV disease appears to be heterogeneous, with Massachusetts, Wisconsin, Minnesota, Maine, and New York accounting for >90% of all cases [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Strain-Dependent Assessment of Powassan Virus Transmission to Ixodes scapularis Ticks

McMinn,

Gallichotte,

Courtney

et al. 2024

Viruses

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Powassan virus (POWV) is an emerging tick-borne encephalitic virus in Lyme disease-endemic sites in North America. Due to range expansion and local intensification of blacklegged tick vector (Ixodes scapularis) populations in the northeastern and upper midwestern U.S., human encephalitis cases are increasingly being reported. A better understanding of the transmission cycle between POWV and ticks is required in order to better predict and understand their public health burden. Recent phylogeographic analyses of POWV have identified geographical structuring, with well-defined northeastern and midwestern clades of the lineage II subtype. The extent that geographic and genetically defined sublineages differ in their ability to infect and be transmitted by blacklegged ticks is unclear. Accordingly, we determined whether there are strain-dependent differences in the transmission of POWV to ticks at multiple life stages. Five recent, low-passage POWV isolates were used to measure aspects of vector competence, using viremic and artificial infection methods. Infection rates in experimental ticks remained consistent between all five isolates tested, resulting in a 12–20% infection rate and some differences in viral load. We confirm that these differences are likely not due to differences in host viremia. Our results demonstrate that blacklegged ticks are susceptible to, and capable of transmitting, all tested strains and suggest that the tick–virus association is stable across diverse viral genotypes.

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The known unknowns of Powassan virus ecology

Cited by 3 publications

References 81 publications

Active Surveillance of Powassan Virus in Massachusetts Ixodes scapularis Ticks, Comparing Detection Using a New Triplex Real-Time PCR Assay with a Luminex Vector-Borne Panel

Active Surveillance of Powassan Virus in Massachusetts Ixodes scapularis Ticks, Comparing Detection Using a New Triplex Real-Time PCR Assay with a Luminex Vector-Borne Panel

Interspecies co-feeding transmission of Powassan virus between a native tick, Ixodes scapularis, and the invasive East Asian tick, Haemaphysalis longicornis

Strain-Dependent Assessment of Powassan Virus Transmission to Ixodes scapularis Ticks

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