The Ectodomain of Glycoprotein from the Candid#1 Vaccine Strain of Junin Virus Rendered Machupo Virus Partially Attenuated in Mice Lacking IFN-αβ/γ Receptor

Abstract

Machupo virus (MACV), a New World arenavirus, is the etiological agent of Bolivian hemorrhagic fever (BHF). Junin virus (JUNV), a close relative, causes Argentine hemorrhagic fever (AHF). Previously, we reported that a recombinant, chimeric MACV (rMACV/Cd#1-GPC) expressing glycoprotein from the Candid#1 (Cd#1) vaccine strain of JUNV is completely attenuated in a murine model and protects animals from lethal challenge with MACV. A rMACV with a single F438I substitution in the transmembrane domain (TMD) of GPC, which is equivalent to the F427I attenuating mutation in Cd#1 GPC, was attenuated in a murine model but genetically unstable. In addition, the TMD mutation alone was not sufficient to fully attenuate JUNV, indicating that other domains of the GPC may also contribute to the attenuation. To investigate the requirement of different domains of Cd#1 GPC for successful attenuation of MACV, we rescued several rMACVs expressing the ectodomain of GPC from Cd#1 either alone (MCg1), along with the TMD F438I substitution (MCg2), or with the TMD of Cd#1 (MCg3). All rMACVs exhibited similar growth curves in cultured cells. In mice, the MCg1 displayed significant reduction in lethality as compared with rMACV. The MCg1 was detected in brains and spleens of MCg1-infected mice and the infection was associated with tissue inflammation. On the other hand, all animals survived MCg2 and MCg3 infection without detectable levels of virus in various organs while producing neutralizing antibody against Cd#1. Overall our data suggest the indispensable role of each GPC domain in the full attenuation and immunogenicity of rMACV/Cd#1 GPC.

Glycoprotein N-linked glycans play a critical role in arenavirus pathogenicity

“…However, substitution F438I or F427I in GPC TMD alone was not able to completely attenuate the virulence of the viruses in vivo [ 31 , 34 ]. We previously reported that replacement of the ectodomain of MACV GPC with that of Cd#1-GPC (MCg1) also attenuated MACV, suggesting that the ectodomain of Cd#1 contains additional attenuation factors [ 37 ]. In this study, we found that the MCg1 chimeric virus frequently underwent mutations in animals to gain two glycans corresponding to the N83 and N166 glycosylation sites in MACV GPC.…”

“…Later, 100% of the MCg1-infected mice contained a population of GPC A168S/T after 42 days of infection ( S2 Table ). Mutations were not observed after five serial passages of MCg1 in vitro [ 37 ] and did not affect MCg1 growth in vitro , which is important for development of a genetically stable and attenuated vaccine candidates [ 30 ]. No mutations occurred in MCg1 in cell culture experiments in our study.…”

“…To identify additional virulence determinants, we then exchanged the MACV GPC ectodomain with the Cd#1 GPC ectodomain while retaining the MACV GP2 TMD and CT. The resulting recombinant virus, named MCg1, was partially attenuated in a IFN-αβ/γ R -/- mouse model of MACV infection, indicating the ectodomain of MACV GPC also contains virulence determinants [ 37 ]. In this study, we analyzed the sequence of the MCg1 viruses isolated from infected animals and frequently identified two substitutions (P85S and A168S/T) that would allow MCg1 to acquire N-linked glycans in GP1 at positions N83 and N166.…”

Infecciones por arenavirus

“…In 1959 the Bolivian hemorrhagic fever was clinically recognized in the provinces of Mamoré, Itenez, Tratamiento. Aunque la infección por arenavirus es una enfermedad potencialmente mortal, la mayor parte de los pacientes presentan un cuadro de gravedad moderada, que necesita solamente adecuada hidratación y antipiréticos y antiinflamatorios (17,35,36). La atención de los pacientes con signos de severos debe tener un manejo agresivo.…”

“…Even though the arenavirus infection is a potentially deadly disease, most of the patient present a moderate severity condition, that only needs proper hydration antipyretics and anti-inflammatories (17,35,36). The care of patients with severe signs must include some aggressive management.…”