Powassan virus (POWV) is a new tick-borne flavivirus (TBFV) that is spreading across North America and Russia. It is a zoonotic infection that can cause encephalitis and meningoencephalitis in humans and is transmitted by several tick species. POWV belongs to the tick-borne encephalitis (TBE) serogroup of flaviviruses and is the only known member of the TBFVs that occurs naturally in both the Old and New Worlds. POWV (lineage I) and deer tick virus are now recognized as two distinct genetic lineages (lineage II). Lineage II has the most genetic variation, implying that it is the ancestral lineage that split due to positive natural selection.
POWV has a single-stranded, positive-sense RNA that is 10.8 kb long. POWV genomic RNA is directly translated into a single, long polypeptide, which is cleaved into ten different proteins by protease. The structural proteins are capsid protein (C), pre-membrane protein/membrane protein (prM/M), and envelope protein (E), while the nonstructural proteins are NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5.
Fig.1 Genomic organization and structure of POWV. (Yang, et al., 2022)
The C protein aids virus budding by binding to the cell membrane and assembling viral RNA into a nucleocapsid, which serves as the core of a mature virus particle.
The E protein is essential for recognizing receptors on the host cell surface and mediating fusion of the viral and cellular membranes. It is composed of three domains: DI, DII, and DIII, with DIII serving as a hotspot epitope for TBFV-neutralizing antibodies.
PrM could be separated into two components: peptide pr and the small envelope protein M. During virion assembly, prM acts as a chaperone for the E protein.
Serology, virus isolation, immunofluorescence assay (IFA), detection of IgM antibodies by ELISA, plaque reduction neutralization testing (PRNT), and RT-PCR are all used in the laboratory to diagnose POWV. The gold standard for laboratory diagnosis of POWV infection is serology. ELISAs and IFAs have been largely replaced in recent years by more convenient medium- to high-throughput, multiplexed microsphere-based immunoassays (MIAs).
Fig.2 Timeline of POWV infection, symptoms, and diagnostic testing. (Hermance & Thangamani, 2017)
Creative Biolabs now offers a wide range of POWV antibody products to help our clients achieve their goals. If your desired antibody is not on our list, please consult with our scientists about antibody discovery, engineering, and customized services. Please feel free to contact us for more details.
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