Antigenic relatedness between arenaviruses defined at the epitope level by monoclonal antibodies. (9/73)

Monoclonal antibodies (MAbs) were produced against two African arenaviruses, Lassa virus and Mopeia virus. Competitive binding analysis of MAbs identified four antigenic sites on the nucleoprotein (NP), two on glycoprotein 1 (GP1) and six on glycoprotein 2 (GP2) of the Josiah strain of Lassa virus. 64 virus isolates from western, central and southern Africa were all consistently distinguishable by MAbs to certain epitopic sites on GP1, GP2 and NP viral proteins. Furthermore, MAbs to Lassa virus GP1 and NP uniformly distinguished viruses from the West African countries of Sierra Leone, Liberia and Guinea from those of Nigeria. GP2-directed MAbs to two African arenaviruses reacted broadly with South American arenaviruses demonstrating that an epitopic site on GP2 may be the most highly conserved antigen in the arenavirus group.  (+info)

Isolation of an arenavirus from a marmoset with callitrichid hepatitis and its serologic association with disease. (10/73)

Callitrichid hepatitis (CH) is an acute, often fatal viral infection of New World primates from the family Callitrichidae. The etiologic agent of CH is unknown. We report here the isolation of an arenavirus from a common marmoset (Callithrix jacchus) with CH by using in vitro cultures of marmoset hepatocytes and Vero-E6 cells. Enveloped virions 67 to 133 nm in diameter with ribosomelike internal structures were seen in infected cultures. Immunofluorescence and Western immunoblot analysis using CH-specific antisera (principally from animals exposed to CH during zoo outbreaks) revealed three antigens in cells infected with this CH-associated virus (CHV). These antigens had the same electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gels as did the nucleocapsid, GP2, and GPC proteins of lymphocytic choriomeningitis virus (LCMV). Monoclonal antibodies specific for these arenavirus proteins also reacted with the three CHV antigens. Conversely, the CH-specific antisera reacted with the nucleocapsid, GP2, and GPC proteins of LCMV. CHV thus appears to be a close antigenic relative of LCMV. The serologic association of CHV with several CH outbreaks implicate it as the etiologic agent of this disease.  (+info)

Molecular characterization of a reassortant virus derived from Lassa and Mopeia viruses. (11/73)

In this article we describe two new complete genomic sequences of Old World Arenaviruses: the Mopeia (MOP) virus and the reassortant MOP/LAS virus, clone 29, or ML29. This reassortant has the large (L) RNA from MOP virus and the small (S) RNA from Lassa (LAS) virus, Josiah strain. Recent studies showed that the ML29 virus is not pathogenic for mice, guinea pigs, or macaques, can completely protect guinea pigs from Lassa virus, and elicit vigorous cell-mediated immunity in immunized monkeys (Lukashevich, I. S., Patterson, J., Carrion, R., Moshkoff, D., Ticer, A., Zapata, J., Brasky, K., Geiger, R., Hubbard, G. B., Bryant, J., and Salvato, M. S., J Virol 79, 13934-13942, 2005). This is a molecular characterization of a reassortant virus, which has been put forward as a live attenuated vaccine candidate against Lassa Fever. Sequence analysis of this reassortant virus revealed 5 non-conservative amino acid substitutions that distinguished it from the parental LAS and MOP viruses. Three substitutions were found outside the conserved RNA-dependent RNA polymerase (RdRp) motifs. A fourth substitution was located between the glycoprotein (GPC)-cleavage site and the putative fusion peptide of GP2. The nucleocapsid protein (NP) contained a fifth substitution in the carboxyl-terminal region of the protein. Two mutations were found within each non-coding terminus of the L segment and one mutation was located in the 3' non-coding region of the S segment of the MOP/LAS virus. ML29 mutations in its genomic termini may have implications for the genetic stability and replication efficiency of ML29 reassortant.  (+info)

Ribozymes which cleave arenavirus RNAs: identification of susceptible target sites and inhibition by target site secondary structure. (12/73)

The development of safe and effective antiviral agents has been a slow process, largely because of the difficulty in distinguishing between virus and host functions; materials toxic to the virus are frequently harmful also to the host in which the agent resides. Recently, techniques which target nucleic acid sequences as a means of reducing gene expression have emerged. This antisense armamentarium includes ribozymes, RNA enzymes which cleave other RNA molecules in a sequence-specific manner. We wish to assess the ability of ribozymes to control animal virus infection. Reasoning that the viruses most vulnerable to ribozyme intervention will be those whose complete life cycle is based on RNA (with no DNA stage), we have begun to develop ribozymes directed toward lymphocytic choriomeningitis virus (LCMV), the prototype of the arenavirus family. Using ribozymes of the hammerhead variety, we have identified several sites on the LCMV genome which can be efficiently cleaved in trans. The efficiency of cleavage is site dependent, and we demonstrate that secondary structure at the target site can abolish ribozyme cleavage. Computer-assisted analysis indicates that much of the LCMV genome may be involved in base pairing, which may render it similarly resistant to ribozyme attack. The few remaining open regions of LCMV lack a GUC target site, on which most studies to date have relied. Here we show that AUC, CUC, and AUU are alternative sites which can be cleaved by trans-acting ribozymes. This finding is important given the aforementioned restriction of available sites, imposed by secondary structure.  (+info)

Tacaribe arenavirus RNA synthesis in vitro is primer dependent and suggests an unusual model for the initiation of genome replication. (13/73)

A Tacaribe virus in vitro system for RNA synthesis was established and found in large part to faithfully reproduce RNA synthesis in vivo. Similar to influenza virus and bunyavirus in vitro systems, this system was also highly dependent on added oligonucleotides. Of the eight tested, only three were active, in the order GpC greater than CpG greater than ApApC. Determination of the 5' ends of the transcripts suggested that the oligonucleotides were acting as primers. In particular, whereas stimulation with CpG (complementary to positions +1 and +2 of the template) led to RNAs whose 5' ends were at position +1 as expected, GpC stimulation led to transcripts whose 5' ends were at position -1 rather than at position +2, as GpC is complementary to positions +2 and +3 of the template. This finding suggests a model for the initiation of genome replication in which pppGpC is first made on the template at positions +2 and +3 but slips backwards on the template so that the 5' end is at position -1 before elongation can continue.  (+info)

Analysis of the glycoprotein gene of Tacaribe virus and neutralization-resistant variants. (14/73)

We have previously generated neutralization-resistant variants of Tacaribe virus in the presence of a monoclonal antibody (MAb) specific for the envelope glycoprotein. The envelope glycoprotein precursor (GPC) genes of two variant viruses were sequenced following polymerase chain reaction amplification of a specific region of the Tacaribe virus S RNA, and compared with the GPC gene of the parental virus. Multiple nucleotide changes in the 3' half of the GPC gene were identified in the variants, suggesting that this part of the gene codes for the envelope glycoprotein of Tacaribe virus recognized by the MAb. Both variants showed unique amino acid substitutions up to 166 residues apart, suggesting that the most likely basis for neutralization resistance was a change in an epitope in which the critical residues are juxtaposed by conformation rather than by proximity in coding.  (+info)

NMR assignment of the arenaviral protein Z from Lassa fever virus. (15/73)

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Analysis of the differential host cell nuclear proteome induced by attenuated and virulent hemorrhagic arenavirus infection. (16/73)

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