Salivary gland extract from the deer tick, Ixodes scapularis, facilitates neuroinvasion by Powassan virus in BALB/c mice

Abstract

Powassan virus (POWV) is a neuroinvasive flavivirus transmitted to mammals by the bite of ixodid ticks. In this study, we sought to investigate the impact of tick salivary gland extract (SGE) on POWV neuroinvasion. BALB/c mice were footpad inoculated with either a high dose or a low dose of POWV, with and without Ixodes scapularis salivary gland extract. Brain and spinal cord were extracted daily, and immunohistochemical techniques were used for temporal tracking of POWV antigen. The temporal pattern of POWV staining showed a caudal to rostral spread of POWV in the brains of mice from both high dose infection groups. For the high dose infection groups, the presence of tick SGE did not influence the spread of POWV in the brain. Mice infected with the low dose of virus alone did not present POWV staining in the brain; however, in the presence of SGE, low dose infected mice presented scattered foci of POWV-infected cells throughout the brain. This study shows that tick SGE facilitates POWV neuroinvasion when mice are infected with the lower dose of POWV. We also found two patterns of central nervous system invasion that were directly influenced by the dose of POWV administered.

Discovery of the Role of Tick Salivary Glands in Enhancement of Virus Transmission—Beginning of an Exciting Story

“…Thus, sialostatin L2 could be considered as a potential SAT factor. Moreover, SGE of I. scapularis was determined to enhance the spread of Powassan virus (POWV) in the mouse brain when the animals were infected with a low viral dose [ 52 ]. All the reported effects can be considered as activities promoting arbovirus replication, transmission and dissemination.…”

Inapparent Tick-Borne Orthoflavivirus Infection in Macaca fascicularis: A Model for Antiviral Drug and Vaccine Research

“…The most convenient and widespread model for studying many orthoflavivirus infections is the laboratory mouse model. For TBEV and POWV, mouse models were extensively used to study the pathogenesis, formation, and dynamics of humoral immune response, and the spectrum and cross-reactivity of antibodies induced by infection [ 43 , 44 , 45 ]. Notably, for these orthoflaviviruses, the corresponding models in susceptible mice recapitulate the pathogenesis of the severe lethal infection that is relatively rare in humans.…”

Alterations in arthropod and neuronal exosomes reduce virus transmission and replication in recipient cells

“…Arthropod-borne flaviviruses are transmitted by the bite of an infected vector such as I. scapularis ticks which are obligate hematophagous parasites [3,23,[25][26][27][28][29][30][31] . The hard ticks, vector/transmit several human pathogens, including tick-borne encephalitis virus (TBEV), Powassan virus (POWV) and Langat virus (LGTV) in the genus flavivirus [25][26][27][28][29][30][31] . There are no known cases of human diseases associated with LGTV, and it does not pose a significant epidemiological threat in comparison to TBEV/POWV [25][26][27][28][29][30][31] .…”

“…The hard ticks, vector/transmit several human pathogens, including tick-borne encephalitis virus (TBEV), Powassan virus (POWV) and Langat virus (LGTV) in the genus flavivirus [25][26][27][28][29][30][31] . There are no known cases of human diseases associated with LGTV, and it does not pose a significant epidemiological threat in comparison to TBEV/POWV [25][26][27][28][29][30][31] .…”