Prevalence and Genetic Characterization of Powassan Virus Strains Infecting Ixodes scapularis in Connecticut

Anderson, John F.; Armstrong, Philip M.

doi:10.4269/ajtmh.2012.12-0294

Cited by 74 publications

(75 citation statements)

References 21 publications

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“…The detection of DTV in 53 pools (49 infectious virus isolated, 4 RNA positive only) of questing I. scapularis collected throughout the Hudson Valley is notable and surpasses the highest total of DTV isolations reported to date [12]. Virus was not isolated from other tick species.…”

Section: Discussionmentioning

confidence: 99%

Isolation of deer tick virus (Powassan virus, lineage II) from Ixodes scapularis and detection of antibody in vertebrate hosts sampled in the Hudson Valley, New York State

et al. 2013

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BackgroundDeer tick virus, DTV, is a genetically and ecologically distinct lineage of Powassan virus (POWV) also known as lineage II POWV. Human incidence of POW encephalitis has increased in the last 15 years potentially due to the emergence of DTV, particularly in the Hudson Valley of New York State. We initiated an extensive sampling campaign to determine whether POWV was extant throughout the Hudson Valley in tick vectors and/or vertebrate hosts.MethodsMore than 13,000 ticks were collected from hosts or vegetation and tested for the presence of DTV using molecular and virus isolation techniques. Vertebrate hosts of Ixodes scapularis (black-legged tick) were trapped (mammals) or netted (birds) and blood samples analyzed for the presence of neutralizing antibodies to POWV. Maximum likelihood estimates (MLE) were calculated to determine infection rates in ticks at each study site.ResultsEvidence of DTV was identified each year from 2007 to 2012, in nymphal and adult I. scapularis collected from the Hudson Valley. 58 tick pools were positive for virus and/or RNA. Infection rates were higher in adult ticks collected from areas east of the Hudson River. MLE limits ranged from 0.2-6.0 infected adults per 100 at sites where DTV was detected. Virginia opossums, striped skunks and raccoons were the source of infected nymphal ticks collected as replete larvae. Serologic evidence of POWV infection was detected in woodchucks (4/6), an opossum (1/6), and birds (4/727). Lineage I, prototype POWV, was not detected.ConclusionsThese data demonstrate widespread enzootic transmission of DTV throughout the Hudson Valley, in particular areas east of the river. High infection rates were detected in counties where recent POW encephalitis cases have been identified, supporting the hypothesis that lineage II POWV, DTV, is responsible for these human infections.

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Section: Discussionmentioning

confidence: 99%

Isolation of deer tick virus (Powassan virus, lineage II) from Ixodes scapularis and detection of antibody in vertebrate hosts sampled in the Hudson Valley, New York State

et al. 2013

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“…In Connecticut, the isolation of two distinct subclades of POWV 40 km apart suggests that the virus was introduced separately into each environment and is maintained in small, stable foci (Anderson and Armstrong 2012). To determine the mechanisms that led to the divergence of POWV into two phylogenetically distinct lineages, several studies have compared nucleotide sequence data, both within and between lineages (Ebel et al 2001, Pesko et al 2010).…”

Section: History Of Powassan Virusmentioning

confidence: 99%

Powassan Virus: An Emerging Arbovirus of Public Health Concern in North America

Hermance

Thangamani

2017

Vector-Borne and Zoonotic Diseases

152

166

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Powassan virus (POWV, Flaviviridae) is the only North American member of the tick-borne encephalitis serogroup of flaviviruses. It is transmitted to small- and medium-sized mammals by Ixodes scapularis, Ixodes cookei, and several other Ixodes tick species. Humans become infected with POWV during spillover transmission from the natural transmission cycles. In humans, POWV is the causative agent of a severe neuroinvasive illness with 50% of survivors displaying long-term neurological sequelae. POWV was recognized as a human pathogen in 1958 when a young boy died of severe encephalitis in Powassan, Ontario, and POWV was isolated from the brain autopsy of this case. Two distinct genetic lineages of POWV are now recognized: POWV (lineage I) and deer tick virus (lineage II). Since the index case in 1958, over 100 human cases of POWV have been reported, with an apparent rise in disease incidence in the past 16 years. This recent increase in cases may represent a true emergence of POWV in regions where the tick vector species are prevalent, or it could represent an increase in POWV surveillance and diagnosis. In the past 5 years, both basic and applied research for POWV disease has intensified, including phylogenetic studies, field surveillance, case studies, and animal model development. This review provides an overview of POWV, including the epidemiology, transmission, clinical disease, and diagnosis of POWV infection. Recent research developments and future priorities with regard to the disease are emphasized.

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“…ticks transmit a large number of human tick-borne disease (TBD) agents including Borrelia burgdoferri , Anaplasma phagocytophilum , Babesia microti , Powassan virus, tick-borne encephalitis, Omsk hemorrhagic fever and Louping hill (Ebel and Kramer, 2004; Yano et al, 2005; Michalski et al, 2006; Růžek et al, 2010; Burri et al, 2011; Anderson and Armstrong, 2012; Lommano et al, 2012; Subramanian et al, 2012; Vannier et al, 2012). The impact of Ixodes spp.…”

Section: Introductionmentioning

confidence: 99%

A blood meal-induced Ixodes scapularis tick saliva serpin inhibits trypsin and thrombin, and interferes with platelet aggregation and blood clotting

Ibelli

Kim

Hill

et al. 2014

International Journal for Parasitology

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Ixodes scapularis is a medically important tick species that transmits causative agents of important human tick-borne diseases including borreliosis, anaplasmosis and babesiosis. An understanding of how this tick feeds is needed prior to the development of novel methods to protect the human population against tick-borne disease infections. This study characterizes a blood meal-induced I. scapularis (Ixsc) tick saliva serine protease inhibitor (serpin (S)), in-house referred to as IxscS-1E1. The hypothesis that ticks use serpins to evade the host's defense response to tick feeding is based on the assumption that tick serpins inhibit functions of protease mediators of the host's anti-tick defense response. Thus, it is significant that consistent with hallmark characteristics of inhibitory serpins, Pichia pastoris-expressed recombinant IxscS-1E1 (rIxscS-1E1) can trap thrombin and trypsin in SDS- and heat-stable complexes, and reduce the activity of the two proteases in a dose-responsive manner. Additionally, rIxscS-1E1 also inhibited, but did not apparently form detectable complexes with, cathepsin G and factor Xa. Our data also show that rIxscS-1E1 may not inhibit chymotrypsin, kallikrein, chymase, plasmin, elastase and papain even at a much higher rIxscS-1E1 concentration. Native IxscS-1E1 potentially plays a role(s) in facilitating I. scapularis tick evasion of the host's hemostatic defense as revealed by the ability of rIxscS-1E1 to inhibit adenosine diphosphate (ADP)- and thrombin-activated platelet aggregation, and delay activated partial prothrombin time (APTT) and thrombin time (TT) plasma clotting in a dose-responsive manner. We conclude that native IxscS-1E1 is part of the tick saliva protein complex that mediates its anti-hemostatic, and potentially inflammatory, functions by inhibiting the actions of thrombin, trypsin and other yet unknown trypsin-like proteases at the tick-host interface.

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Prevalence and Genetic Characterization of Powassan Virus Strains Infecting Ixodes scapularis in Connecticut

Abstract: Abstract. A total of 30 Powassan virus (POWV) isolates from Ixodes scapularis collected from Bridgeport and North Branford, CT in

Cited by 74 publications

References 21 publications

Isolation of deer tick virus (Powassan virus, lineage II) from Ixodes scapularis and detection of antibody in vertebrate hosts sampled in the Hudson Valley, New York State

Isolation of deer tick virus (Powassan virus, lineage II) from Ixodes scapularis and detection of antibody in vertebrate hosts sampled in the Hudson Valley, New York State

Powassan Virus: An Emerging Arbovirus of Public Health Concern in North America

A blood meal-induced Ixodes scapularis tick saliva serpin inhibits trypsin and thrombin, and interferes with platelet aggregation and blood clotting

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