An E460D #substitution in the #NS5 protein of #TBE virus confers #resistance to the #inhibitor #Galidesivir (BCX4430) and also attenuates the virus for mice (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

An E460D substitution in the NS5 protein of tick-borne encephalitis virus confers resistance to the inhibitor Galidesivir (BCX4430) and also attenuates the virus for mice

Ludek Eyer, Antoine Nougairède, Marie Uhlířová, Jean-Sélim Driouich, Darina Zouharová, James J. Valdés, Jan Haviernik, Ernest A. Gould, Erik De Clercq, Xavier de Lamballerie, Daniel Ruzek

DOI: 10.1128/JVI.00367-19

 

ABSTRACT

The adenosine analogue Galidesivir (BCX4430), a broad-spectrum RNA virus inhibitor, has entered a Phase 1 clinical safety and pharmacokinetics study in healthy subjects and is under clinical development for treatment of Ebola virus infection. Moreover, Galidesivir also inhibits the reproduction of tick-borne encephalitis virus (TBEV) and numerous other medically important flaviviruses. Until now, studies of this antiviral agent have not yielded resistant viruses. Here, we demonstrate that an E460D substitution, in the active site of TBEV RNA-dependent-RNA-polymerase (RdRp), confers resistance to Galidesivir in cell culture. Galidesivir-resistant TBEV exhibited no cross-resistance to structurally different antiviral nucleoside analogues, such as 7-deaza-2′-C-methyladenosine, 2′-C-methyladenosine and 4′-azido-aracytidine. Although, the E460D substitution led only to a subtle decrease in viral fitness in cell culture, Galidesivir-resistant TBEV was highly attenuated in vivo, with 100% survival rate and no clinical signs observed in infected mice. Furthermore, no virus was detected in serum, spleen or brain of mice inoculated with the Galidesivir-resistant TBEV. Our results contribute to understanding the molecular basis of Galidesivir antiviral activity, flavivirus resistance to nucleoside inhibitors and the potential contribution of viral RdRp to flavivirus neurovirulence.

 

IMPORTANCE

Tick-borne encephalitis virus (TBEV) is a pathogen that causes severe human neuroinfections in Europe and Asia and for which there is currently no specific therapy. We have previously found that Galidesivir (BCX4430), a broad-spectrum RNA virus inhibitor, which is under clinical development for treatment of Ebola virus infection, has a strong antiviral effect against TBEV. For any antiviral drug, it is important to generate drug-resistant mutants to understand how the drug works. Here, we produced TBEV mutants resistant to Galidesivir and found that the resistance is caused by a single amino acid substitution in an active site of the viral RNA-dependent RNA polymerase, an enzyme which is crucial for replication of viral RNA genome. Although, this substitution led only to a subtle decrease in viral fitness in cell culture, Galidesivir-resistant TBEV was highly attenuated in a mouse model. Our results contribute to understanding the molecular basis of Galidesivir antiviral activity.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Antivirals; Drugs Resistance; Galidesivir; Flavivirus; Tick-Borne Encephalitis Virus.

——

Advertisements

#Molecular basis of a protective/neutralizing #monoclonal #antibody targeting envelope proteins of both #tick-borne #encephalitis virus and louping ill virus (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Molecular basis of a protective/neutralizing monoclonal antibody targeting envelope proteins of both tick-borne encephalitis virus and louping ill virus

Xu Yang, Jianxun Qi, Ruchao Peng, Lianpan Dai, Ernest A. Gould, George F. Gao, Po Tien

DOI: 10.1128/JVI.02132-18

 

ABSTRACT

Tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) are members of the tick-borne flaviviruses (TBFVs) in the family Flaviviridae, which cause encephalomeningitis and encephalitis in humans and other animals. Although vaccines against TBEV and LIV are available, infection rates are rising due to the low vaccination coverage. To date, no specific therapeutics have been licensed. Several neutralizing monoclonal antibodies (MAbs) show promising effectiveness in the control of TBFVs, but the underlying molecular mechanisms are yet to be characterized. Here, we determined the crystal structures of LIV envelope protein (E) and report the comparative structural analysis of a TBFV broadly neutralizing murine MAb (MAb 4.2) in complex with either LIV or TBEV E proteins. The structures reveal that MAb 4.2 binds to the lateral ridge of Domain III (EDIII) of LIV-E or TBEV-E, an epitope also reported for other potently neutralizing MAbs against mosquito-borne flaviviruses (MBFVs), but adopts a unique binding orientation. Further structural analysis suggested that MAb 4.2 may neutralize flavivirus infection by preventing the structural rearrangement required for membrane fusion during virus entry. These findings extend our understanding of the vulnerability of TBFVs and other flaviviruses (including MBFVs) and provide an avenue for antibody-based TBFVs antiviral development.

 

Importance

Understanding the mechanism of antibody neutralization/protection against a virus is crucial for antiviral counter-measures development. Tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) are tick-borne flaviviruses (TBFVs) in the family Flaviviridae. They cause encephalomeningitis and encephalitis in humans and other animals. Although vaccines for both viruses are available, infection rates are rising due to the low vaccination coverage. In this study, we solved the crystal structures of LIV envelope protein (E) and a broadly-neutralizing/protective TBFV MAb, MAb 4.2, in complex with E from either TBEV or LIV. Key structural features shared by TBFV E proteins were analyzed. Structures of E-antibody complexes show that MAb 4.2 targets the lateral ridge of both TBEV and LIV E proteins, a vulnerable site in flaviviruses for other potent neutralizing MAbs. Thus, this site represents a promising target for TBFV antiviral development. Further, these structures provide important information for understanding TBFV antigenicity.

Copyright © 2019 American Society for Microbiology. All Rights Reserved.

Keywords: Flavivirus; Tick-borne encephalitis virus; Louping ill virus; Monoclonal antibodies.

——

#Serological Evidence of #Tick-Borne #Encephalitis and #WNV #Infections Among #Children with #Arthritis in #Turkey (Vector Borne Zoo Dis., abstract)

[Source: Vector Borne and Zoonotic Diseases, full page: (LINK). Abstract, edited.]

Serological Evidence of Tick-Borne Encephalitis and West Nile Virus Infections Among Children with Arthritis in Turkey

Huseyin Yilmaz, Kenan Barut, Asiye Karakullukcu, Ozgur Kasapcopur, Bekir Kocazeybek, Eda Altan Tarakci, Utku Y. Cizmecigil, Aysun Yilmaz, Zahide Bilgin, Meltem Ulutas Esatgil, Christine Klaus, Juergen A. Richt, and Nuri Turan

Published Online: 28 Jan 2019 / DOI: https://doi.org/10.1089/vbz.2018.2349

 

Abstract

Tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are mainly transmitted by arthropod vectors to vertebrate hosts including humans, resulting in fever and neurological signs. The aim of this study was to investigate the presence of antibodies to TBEV and WNV, and TBEV-RNA and WNV-RNA in Turkish children with fever and/or arthritis. For this purpose, 110 sera and buffy-coat samples were collected; sera were analyzed by indirect enzyme-linked immunosorbent assay for the presence of IgM and IgG antibodies to TBEV and WNV, and buffy-coat-derived white blood cells were analyzed by quantitative real-time RT-PCR for TBEV-RNA and WNV-RNA. IgM antibodies to TBEV were detected in five children between the ages of 3 and 7 years; no IgG antibodies to TBEV were detected. IgG antibodies to WNV were detected in two children and IgM antibodies to WNV were detected in six children, between the ages of 3 and 7 years. One of the children had IgM antibodies to WNV and to TBEV. Children who had antibodies to TBEV and WNV had fever and/or arthritis but no obvious neurological signs. Molecular diagnostic approaches revealed that neither TBEV-RNA nor WNV-RNA was present in any of the buffy-coat samples, not even in children with IgM-specific antibodies. Our serological results indicate that children in Turkey are exposed to TBEV and WNV.

Keywords: Arbovirus; Tick-borne encephalitis; WNV; Seroprevalence; Arthritis; Turkey.

—–

A #Serosurvey of #Flavivirus #Infection in #Horses and #Birds in #Slovakia (Vector Borne Zoo Dis., abstract)

[Source: Vector Borne and Zoonotic Diseases, full page: (LINK). Abstract, edited.]

Vector-Borne and Zoonotic Diseases

A Serosurvey of Flavivirus Infection in Horses and Birds in Slovakia

To cite this article: Csank Tomáš, Drzewnioková Petra, Korytár Ľuboš, Major Peter, Gyuranecz Miklós, Pistl Juraj, and Bakonyi Tamás. Vector-Borne and Zoonotic Diseases. February 2018, ahead of print. https://doi.org/10.1089/vbz.2017.2216

Online Ahead of Print: February 13, 2018

Author information: Tomáš Csank,1 Petra Drzewnioková,1 Ľuboš Korytár,2 Peter Major,3 Miklós Gyuranecz,4 Juraj Pistl,1 and Tamás Bakonyi5,6

1 Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy (UVMP) in Košice, Košice, Slovakia. 2 Department of Environment, Veterinary Legislation and Economy, University of Veterinary Medicine and Pharmacy (UVMP) in Košice, Košice, Slovakia. 3 Department of Clinic for Birds and Exotic Animals, University of Veterinary Medicine and Pharmacy (UVMP) in Košice, Košice, Slovakia. 4 Institute for Veterinary Medical Research, MTA Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary. 5 Department of Microbiology and Infectious Diseases, University of Veterinary Medicine, Budapest, Hungary. 6 Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of Virology, University of Veterinary Medicine, Vienna, Vienna, Austria.

Address correspondence to: Tomáš Csank, PhD, Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy (UVMP) in Košice, Komenského 73, Košice 04181, Slovakia, E-mail: tomas.csank@uvlf.sk

 

ABSTRACT

In central Europe, at least three flaviviruses circulate among vectors and vertebrate hosts. West Nile virus (WNV) and Usutu virus (USUV) are mosquito-borne viruses maintained in the nature by enzootic cycle between mosquitoes and birds. Tick-borne encephalitis virus (TBEV) is a flavivirus causing annual human cases in Slovakia. The aim of this study is the prevalence assessment of flavivirus infections in horses (n = 145) and birds (n = 109) by enzyme-linked immunosorbent assay (ELISA) and confirmation by neutralization test (VNT). WNV antibodies have been detected in 11.7% of tested horses and 11.9% of tested birds and confirmed in 6.9% of horse and 9.2% of bird samples. None of the WNV seropositive or dubious horses had WNV IgM (ELISA), and none of the tested horses had USUV neutralizing antibodies. Autochthonous WNV infections have been confirmed in 16.7% of horses without international travelling history. Most of them were from western Slovakia with known endemic WNV transmission. An autochthonous WNV infection in a horse from highland area of Kremnické vrchy (central Slovakia) with unknown data of WNV circulation and without travelling history was detected. TBEV antibody was detected in 6.2% of horses and in 3.4% has been confirmed. In two horses, WNV and TBEV infection could not be distinguished. Confirmed WNV seropositive were eight raptors showing nonspecific signs or suffering from trauma, one white stork, and one house sparrow. The sparrow was caught in a locality in eastern Slovakia, where WNV RNA had been previously detected in sparrows. USUV neutralizing antibodies were present in pooled sample from four Eurasian great tits. Because of insufficient volume, TBEV VNT was not carried out in birds. Results further prove the endemicity of WNV and other vector-borne flaviviruses in natural and accidental hosts in Slovakia, giving better insight in flavivirus epidemiology in European countries in general.

Keywords: Slovakia; Flavivirus; WNV; Usutu Virus; TBEV; Horses; Wild birds.

——-

#Viperin restricts #Zika virus and #TBE virus #replication by targeting NS3 for proteasomal degradation (J Virol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

J Virol. 2018 Jan 10. pii: JVI.02054-17. doi: 10.1128/JVI.02054-17. [Epub ahead of print]

Viperin restricts Zika virus and tick-borne encephalitis virus replication by targeting NS3 for proteasomal degradation.

Panayiotou C1, Lindqvist R1, Kurhade C1, Vonderstein K1, Pasto J1, Edlund K1, Upadhyay AS1, Överby AK2.

Author information: 1 Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden. Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden. 2 Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden. Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden. anna.overby@umu.se.

 

Abstract

Flaviviruses are arthropod-borne viruses that constitute a major global health problem, with millions of human infections annually. Their pathogenesis ranges from mild illness to severe manifestations such as hemorrhagic fever and fatal encephalitis. Type I interferons (IFNs) are induced in response to viral infection, and stimulate the expression of interferon-stimulated genes (ISGs), including that encoding viperin (virus-inhibitory protein, endoplasmic reticulum-associated, IFN-inducible), which shows antiviral activity against a broad spectrum of viruses including several flaviviruses. Here we describe a novel antiviral mechanism exerted by viperin against two prominent flaviviruses, tick-borne encephalitis virus (TBEV) and Zika virus (ZIKV). Viperin was found to interact and co-localize with the structural proteins pre-membrane (prM) and envelope (E) of TBEV, as well as the non-structural (NS) proteins NS2A, NS2B, and NS3. Interestingly, viperin expression reduced the NS3 protein level, and the stability of the other interacting viral proteins, but only in the presence of NS3. We also found that although viperin interacted with NS3 of mosquito-borne flaviviruses (ZIKV, Japanese encephalitis virus, and yellow fever virus), only ZIKV was sensitive to the antiviral effect of viperin. This sensitivity correlated with viperin’s ability to induce proteasome-dependent degradation of NS3. ZIKV and TBEV replication was rescued completely when NS3 was overexpressed, suggesting that the viral NS3 is the specific target of viperin. In summary, we present here a novel antiviral mechanism of viperin that is selective for specific viruses in the genus Flavivirus, affording the possibility of new drug targets that can be used for therapeutic intervention.

 

Importance

Flaviviruses are a group of enveloped RNA viruses that cause severe diseases in humans and animals worldwide, but no antiviral treatment is yet available. Viperin, a host protein produced in response to infection, effectively restricts the replication of several flaviviruses but the exact molecular mechanisms have not been elucidated. Here we have identified a novel mechanism exerted by viperin to inhibit the replication of two flaviviruses; tick-borne encephalitis virus (TBEV) and Zika virus (ZIKV). Viperin induced selective degradation via the proteasome of TBEV and ZIKV non-structural 3 (NS3) protein, which is involved in several steps of the viral life cycle. Furthermore, viperin also reduced the stability of several other viral proteins in a NS3-dependent manner, suggesting a central role of NS3 in viperin’s anti-flaviviral activity. Taken together, our work shows important similarities and differences among the members of the genus Flavivirus, and could lead to the possibility of therapeutic intervention.

PMID: 29321318 DOI: 10.1128/JVI.02054-17

Keywords: Flavivirus; Zika Virus; Viperin.

——

Unrecognized Subclinical #Infection with #Tick-Borne #Encephalitis Virus, #Japan (@CDC_EIDjournal, abstract)

[Source: US Centers for Disease Control and Prevention (CDC), Emerging Infectious Diseases Journal, full page: (LINK). Abstract, edited.]

Volume 23, Number 10—October 2017 / Research Letter

Unrecognized Subclinical Infection with Tick-Borne Encephalitis Virus, Japan

Kentaro Yoshii, Reiji Kojima, and Hiroshi Nishiura

Author affiliations: Hokkaido University, Sapporo, Japan (K. Yoshii); Japan Self-Defense Forces Sapporo Hospital, Sapporo (R. Kojima); University of Yamanashi, Yamanashi, Japan (R. Kojima); Hokkaido University, Sapporo (H. Nishiura)

 

Abstract

During early 2017, we conducted a seroepidemiologic investigation for tick-borne encephalitis virus among 291 Japan Self-Defense Forces members in Hokkaido. Two (0.7%) tested positive. Neither had clinically apparent symptoms after removing ticks.

Keywords: Tick-Borne Encephalitis; Japan.

——

#Powassan Virus: An Emerging #Arbovirus of #PublicHealth #Concern in North #America (Vector Borne Zoo Dis., abstract)

[Source: Vector Borne and Zoonotic Diseases, full page: (LINK). Abstract, edited.]

Vector-Borne and Zoonotic Diseases

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

To cite this article: Hermance Meghan E. and Thangamani Saravanan. Vector-Borne and Zoonotic Diseases. May 2017, ahead of print. doi:10.1089/vbz.2017.2110.

Online Ahead of Print: May 12, 2017

Author information: Meghan E. Hermance1 and Saravanan Thangamani1,2,3

1Department of Pathology, University of Texas Medical Branch, Galveston, Texas. 2Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas. 3Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas.

© Meghan E. Hermance and Saravanan Thangamani 2017; Published by Mary Ann Liebert, Inc. This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Mary Ann Liebert, Inc. offers reprint services for those who want to order professionally produced copies of articles published under the Creative Commons Attribution (CC BY) license. To obtain a price quote, email Reprints@liebertpub.com. Please include the article’s title or DOI, quantity, and delivery destination in your email.

Address correspondence to: Saravanan Thangamani, Department of Pathology, University of Texas Medical Branch (UTMB), 301 University Boulevard, Galveston, TX 77555-0609, E-mail: sathanga@utmb.edu

 

ABSTRACT

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.

Keywords: Powassan Virus; Ticks; Tick-borne Encephalitis; USA; Flavivirus.

——-