Josiah Strain Of Lassa Virus Research Articles

Zidampidine, an aryl phosphate derivative of AZT: in vivo pharmacokinetics, metabolism, toxicity, and anti-viral efficacy against hemorrhagic fever caused by Lassa virus

The pharmacokinetics, metabolism, and toxicity of Zidampidine, an aryl phosphate derivative of AZT, 3′-azidothymidine-5′-[p-bromophenyl methoxyalaninyl phosphate] were investigated in CD-1 mice. Following iv injection, Zidampidine was rapidly converted to its metabolites Ala-AZT-MP and AZT. Zidampidine was not toxic to mice at doses up to 250mg/kg. We next examined the therapeutic effect of Zidampidine in CBA mice challenged with intracerebral injections of the Josiah strain of Lassa virus. Mice were treated either with vehicle or non-toxic doses of Zidampidine administered intraperitoneally 24h prior, 1h prior, and 24, 48, 72, and 96h after virus inoculation. The probability of survival following the Lassa challenge was significantly improved for Zidampidine-treated mice (Kaplan Meier, Log-Rank p value<0.0001). This pilot study provides the basis for future preclinical evaluation of Zidampidine and its potential as a new agent for the treatment of viral hemorrhagic fevers caused by Lassa virus.

Stampidine prevents mortality in an experimental mouse model of viral hemorrhagic fever caused by lassa virus.

BackgroundThe potential use of microorganisms as agents of biological warfare (BW) is a growing concern. Lassa virus, a member of the Arenavirus class of Hemorrhagic fever (HF) viruses has emerged as a worldwide concern among public health officials. The purpose of the present study was to further elucidate the antiviral activity spectrum of stampidine, a novel nucleoside analog with potent anti-viral activity against the immunodeficiency viruses HIV-1, HIV-2, and FIV, by examining its effects on survival of mice challenged with Lassa virus.MethodsWe examined the therapeutic effect of Stampidine in CBA mice inoculated with intracerebral injections of the Josiah strain of Lassa virus. Mice were treated either with vehicle or nontoxic doses of stampidine administered intraperitoneally 24 hours prior to, 1 hour prior to, and 24 hours, 48 hours, 72 hours, and 96 hours after virus inoculation.ResultsThe probability of survival following the Lassa challenge was significantly improved for stampidine treated mice (Kaplan Meier, Chi-squared = 11.7, df = 2, Log-Rank p-value = 0.003).ConclusionTherefore, stampidine shows clinical potential as a new agent for treatment of viral hemorrhagic fevers caused by Lassa virus.

Antigenic relatedness between arenaviruses defined at the epitope level by monoclonal antibodies

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.

Nucleotide sequence of the S RNA of Lassa virus (Nigerian strain) and comparative analysis of arenavirus gene products

The nucleotide sequence of the small (S) genomic RNA of Lassa virus (strain GA391, of Nigerian origin) has been determined. The RNA has features which conform to those seen in most other arenavirus S RNAs which have been characterised, including conserved terminal sequences, an ambisense arrangement of the coding regions for the precursor glycoprotein (GPC) and nucleocapsid (N) proteins and an intergenic region capable of forming a base-paired “hairpin” structure. Comparison of the nucleotide sequence with that of the Josiah strain of Lassa virus (from Sierra Leone) reveals considerable nucleotide divergence in the third base of codons in the reading frames of all three proteins, although the resulting protein sequences are highly conserved, with 92, 94 and 91% identical residues for the mature glycoproteins G1 and G2 and the N protein, respectively. Sequence alignments of the available arenavirus structural proteins and dendrograms summarising the relationships between the viral proteins are presented.

Nucleotide sequence of the Lassa virus (Josiah strain) S genome RNA and amino acid sequence comparison of the N and GPC proteins to other arenaviruses

The complete nucleotide sequence of the S genome RNA of the Josiah strain of Lassa virus was determined from cloned cDNA. The S RNA is 3402 nucleotides long with a calculated molecular weight of 1.09 × 10 6 Da. The nucleotide base composition is 26.84% adenine, 21.40% guanine, 22.75% cytosine, and 29.01% uridine. The 5′ and 3′ terminal nucleotide sequences are conserved and complimentary for 19 nucleotides, the nucleoprotein and glycoprotein genes are arranged in ambisense coding strategy, and the intergenic region contains an inverted complimentary sequence, as do all other arenavirus S RNAs characterized to date. Amino acid sequence comparisons between the nucleoproteins and glycoproteins of the Josiah and Nigerian (N sequences only) strains of Lassa virus, the WE and ARM strains of lymphocytic choriomeningitis virus (LCMV), Tacaribe, and Pichinde viruses are presented. These findings reveal that the G2 envelope glycoprotein is more conserved among different arenaviruses than the internal nucleoprotein.

Construction of a recombinant vaccinia virus expressing the Lassa virus glycoprotein gene and protection of guinea pigs from a lethal Lassa virus infection

A cloned cDNA (1.65 kb) containing the complete glycoprotein gene of the Josiah strain of Lassa virus was inserted into the thymidine kinase (TK) gene of the New York Board of Health (WYETH) strain of vaccinia virus. The Lassa virus glycoprotein precursor, GPC, and the posttranslational cleavage products, G1 and G2, were shown by Western blot analysis to be properly expressed in cells infected with the recombinant virus. Northern blot hybridization of total cytoplasmic RNA extracted from recombinant virus infected cells demonstrated the presence of RNA transcripts of appropriate size considering the site of transcription initiation from the vaccinia P7.5 promoter, the size of the Lassa glycoprotein gene, and the presumed location of the transcription terminator in the vaccinia thymidine kinase gene. All guinea pigs vaccinated with the recombinant virus survived a lethal challenge infection with Lassa virus, whereas 80% of control animals died. The vaccinated guinea pigs did, however, develop transient, low-grade, fevers and detectable viremias following infection with Lassa virus, indicating that protection was not complete.

Effect of environmental factors on aerosol-induced Lassa virus infection.

Previous studies suggested that the most frequent means of transmission of Lassa virus was by either direct or indirect contact with infectious material. Aerosol stability and respiratory infectivity of the Josiah strain of Lassa virus were assessed to determine the effect of environmental factors on aerosol-induced infection. The stability of the virus in aerosol, particularly at low relative humidity (30% RH), plus the ability of the virus to infect guinea pigs and monkeys via the respiratory route emphasize the potential for aerosol transmission of Lassa virus. Biological half-lives at both 24 and 32 degrees C ranged from 10.1 to 54.6 min, and were sufficient for aerosol dispersion of virus to considerable distances in natural situations. Infectivity of Lassa virus in small particle aerosol was demonstrated in outbred guinea pigs and cynomolgus monkeys using dynamic aerosol equipment. Monkeys exposed to inhaled doses to 465 PFU were infected and died. The median infectious dose (ID50) for guinea pigs was 15 PFU, yet a definitive median lethal aerosol dose (LD50) could not be established. Organ tropism of aerosol-induced Lassa virus infections in outbred guinea pigs was similar to that previously reported for inbred guinea pigs infected by subcutaneous inoculation.