Summary auto-generated
Researchers sequenced the L gene of Lassa fever virus, which encodes the viral RNA-dependent RNA polymerase (RdRp). The L protein is predicted to be 2,218 amino acids long with a molecular mass of 253 kDa, notably preceded by an unusually large 157-nucleotide non-coding region. The protein contains six conserved amino acid motifs characteristic of RdRp across segmented negative-stranded viruses, including motifs involved in catalytic activity and RNA binding. Phylogenetic analysis of 20 segmented negative-stranded viruses revealed that arenavirus L proteins form a distinct cluster divided into two lineages: Lassa-lymphocytic choriomeningitis viruses and Tacaribe-Pichinde viruses. The researchers produced monospecific antiserum against a highly conserved central domain peptide (residues 1121-1153) and successfully immunoprecipitated a 250 kDa protein from both Lassa and lymphocytic choriomeningitis virus-infected cells. This confirmed that the predicted protein sequence corresponds to an actual viral product, validating computational predictions and supporting the identification of this protein as the viral polymerase.
Key findings
- The Lassa virus L gene encodes a 2,218 amino acid, 253 kDa putative RNA-dependent RNA polymerase with six conserved motifs typical of segmented negative-stranded virus polymerases
- Phylogenetic analysis based on RdRp sequences divided arenavirus L proteins into two distinct lineages: Lassa-lymphocytic choriomeningitis and Tacaribe-Pichinde
- Monospecific antiserum against a conserved central domain peptide successfully precipitated a 250 kDa protein product from infected cells, confirming the predicted protein exists as a functional viral product
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Abstract
The large (L) RNA segment of Lassa fever virus (LAS) encodes a putative RNA-dependent RNA polymerase (RdRp or L protein). Similar to other arenaviruses, the LAS L protein is encoded on the genome-complementary strand and is predicted to be 2218 amino acids in length (253 kDa). It has an unusually large non-coding region adjacent to its translation start site. The LAS L protein contains six motifs of conserved amino acids that have been found among arenavirus L proteins and core RdRp of other segmented negative-stranded (SNS) viruses (Arena-, Bunya- and Orthomyxoviridae). Phylogenetic analyses of the RdRp of 20 SNS viruses reveals that arenavirus L proteins represent a distinct cluster divided into LAS-lymphocytic choriomeningitis and Tacaribe-Pichinde virus lineages. Monospecific serum against a synthetic peptide corresponding to the most conserved central domain precipitates a 250 kDa product from LAS and lymphocytic choriomeningitis virus-infected cells.