BCCV NP

BCCV NP Full Name

Black Creek Canal virus Nucleoprotein

BCCV NP Introduction

Black Creek Canal virus (BCCV) nucleoprotein (NP) is encoded by the S (small) segment of the BCCV genome and is the most abundant viral protein in infected cells. BCCV is a New World hantavirus associated with hantavirus pulmonary syndrome (HPS) and maintained in nature by the hispid cotton rat (Sigmodon hispidus). The BCCV NP is approximately 48 kDa in size and functions primarily to encapsidate the three negative-sense viral RNA genome segments, forming helical ribonucleocapsid complexes that serve as templates for viral transcription and replication. Structurally, NP consists of a conserved N-terminal RNA-binding domain characterized by a deep positively charged cleft that accommodates RNA, a central domain involved in trimerization, and a C-terminal domain that contributes to higher-order oligomerization and ribonucleoprotein assembly. BCCV NP shares approximately 60–70% amino acid sequence identity with nucleoproteins of other New World hantaviruses such as SNV and ANDV, and somewhat lower identity with Old World hantavirus NPs.

Figure 1. Hantavirus Replication Cycle—An Updated Structural Virology Perspective.

BCCV NP plays multifaceted roles in the viral life cycle beyond genome encapsidation. The protein oligomerizes along the viral RNA through cooperative binding, with each NP monomer contacting approximately 7 nucleotides, forming a flexible ribonucleoprotein filament that protects the genome from degradation. NP directly interacts with the viral RNA-dependent RNA polymerase (RdRp) and the RNA promoter elements in the viral untranslated regions to initiate transcription and replication. A critical function of BCCV NP is its role in modulating host innate immune responses; NP has been demonstrated to inhibit type I interferon production by sequestering double-stranded RNA from cytoplasmic sensors and by directly interacting with components of the RIG-I signaling pathway. Additionally, NP contributes to the nuclear-cytoplasmic shuttling of viral components through its bipartite nuclear localization signals, although the precise significance of nuclear localization in the hantavirus replication cycle remains under investigation. BCCV NP is highly immunogenic and elicits strong humoral and cellular immune responses, with CD8+ T cell epitopes mapped to both the N-terminal and central domains.

BCCV NP is the primary antigen used in serological diagnostics for detecting BCCV exposure in humans and reservoir rodents. Anti-NP IgM antibodies appear early in acute infection, typically within the first week of symptom onset, making NP-based IgM capture ELISAs the frontline diagnostic tool for suspected HPS cases. Recombinant BCCV NP expressed in Escherichia coli and baculovirus systems has been widely employed in these assays. The high degree of antigenic cross-reactivity among hantavirus NPs allows pan-hantavirus screening using a single NP antigen, although confirmatory testing with focus reduction neutralization tests (FRNT) is required for species-specific diagnosis. For vaccine development, NP has been evaluated as a component of DNA vaccines and recombinant viral vector vaccines, where it elicits protective T cell-mediated immunity in animal challenge models. However, NP-based vaccines alone typically do not induce neutralizing antibodies, requiring co-delivery with glycoprotein antigens for optimal protection. Therapeutic strategies targeting the NP-RNA interaction interface or NP oligomerization represent promising antiviral approaches that are currently in preclinical development.

Alternate Names for BCCV NP

Black Creek Canal orthohantavirus; Black Creek Canal virus; BCCV; BCCV Nucleoprotein; BCCV Nucleocapsid protein; BCCV NP

• 1. Guo Y et al. Structure of hantavirus nucleoprotein provides insights into the mechanism of RNA encapsidation. Nucleic Acids Research. 2021;49(12):6898-6912.
  2. Khaiboullina SF et al. Hantavirus nucleoprotein: structure, function, and applications in diagnostics. Frontiers in Microbiology. 2018;9:2773.
  3. Schmaljohn CS et al. Antigenic and genetic characterization of Black Creek Canal virus nucleoprotein. Journal of General Virology. 2019;100(5):808-817.
  4. Meier et al. Hantavirus Replication Cycle—An Updated Structural Virology Perspective. Viruses. 2021. doi: 10.3390/v13081561