ABSTRACT
In this study we elucidated the molecular character of MaTu-MX, previously described as an unusual transmissible agent. Amino acid sequencing of peptides generated from a 58-kDa MX-related protein purified from MaTu human carcinoma cells allowed us to identify it as a nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV). Northern blot analysis detected LCMV-specific RNAs in MaTu cells. Comparative immunoprecipitations showed cross-reactivity between NP of LCMV strain WE and MX NP. Using RT-PCR, we have cloned MX NP cDNA. According to sequence comparison, MX LCMV is as closely related to both LCMV strains WE and Armstrong as these strains are to one another. Based on this finding we propose that MX is a new strain of LCMV. We also showed that the stability of MX NP in MaTu cells is very high and that the virus is transmissible by cell-to-cell contact or by cell-free extract to human HeLa and monkey Vero cells, but not to human AGS, canine MDCK, mouse NIH 3T3, and hamster CHO cells. Finally, employing MX LCMV NP in immunoprecipitation and solid-phase radioimmunoassay, we found 37.5% prevalence of anti-LCMV antibodies in human sera, suggesting possible horizontal spread of the virus in the human population.
Subject(s)
Lymphocytic Choriomeningitis/transmission , Lymphocytic choriomeningitis virus/isolation & purification , Nucleoproteins/isolation & purification , Tumor Cells, Cultured/virology , Viral Proteins/isolation & purification , 3T3 Cells , Adolescent , Adult , Aged , Amino Acid Sequence , Animals , Antibodies, Viral/blood , Breast Neoplasms/virology , CHO Cells , Coculture Techniques , Cricetinae , DNA, Complementary/chemistry , Disease Transmission, Infectious , Dogs , HeLa Cells , Humans , Lymphocytic Choriomeningitis/immunology , Lymphocytic choriomeningitis virus/genetics , Lymphocytic choriomeningitis virus/immunology , Mice , Middle Aged , Molecular Sequence Data , Nucleoproteins/chemistry , Nucleoproteins/genetics , RNA, Viral/analysis , Viral Proteins/chemistry , Viral Proteins/geneticsABSTRACT
We have cloned and characterised a cDNA encoding Z protein of recently identified MX strain of lymphocytic choriomeningitis virus (LCMV) persistently infecting human MaTu cells. Deduced amino acid sequence of LCMV MX Z protein showed 88.9% identity with that of the LCMV Armstrong (ARM) strain and 80.9% identity with that of the LCMV Traub (TRA) strain. It contained conserved zinc-binding RING finger domain and C-terminal proline-rich region. Northern blot analysis of total RNA from MaTu cells revealed presence of abundant truncated forms of L RNA. Z protein-specific rabbit antibodies were produced to glutathione S-transferase (GST)-Z fusion protein expressed in E. coli and used for the detection of Z protein in MaTu cells. Western blot and immunofluorescence analyses detected relatively high levels of Z protein indicating its role in maintenance of persistent LCMV.
