Molecular Determinants of Pichinde Virus Infection of Guinea Pigs—a Small Animal Model System for Arenaviral Hemorrhagic Fevers

Candid1, a live-attenuated Junin virus vaccine strain, was developed during the early 1980s to control Argentine hemorrhagic fever, a severe and frequently fatal human disease. Six amino acid substitutions were found to be unique to this vaccine strain, and their role in virulence attenuation in mice was analyzed using a series of recombinant viruses. Our results indicate that Candid1 is attenuated in mice through a single amino acid substitution in the transmembrane domain of the G2 glycoprotein. This work provides insight into the molecular mechanisms of attenuation of the only arenavirus vaccine currently available.

mentioning

confidence: 99%

The Major Determinant of Attenuation in Mice of the Candid1 Vaccine for Argentine Hemorrhagic Fever Is Located in the G2 Glycoprotein Transmembrane Domain

Albariño

Bird

Chakrabarti

et al. 2011

“…We have previously developed a reverse genetics system to generate infectious PICV from two plasmids that produce full-length antigenomic strands of the L and S RNAs (23). Using this reverse genetics system, we have characterized the functional mechanisms of viral virulence determinants and the biological roles of arenaviral proteins (13,(24)(25)(26)(27)(28).…”

mentioning

confidence: 99%

A Novel Live Pichinde Virus-Based Vaccine Vector Induces Enhanced Humoral and Cellular Immunity after a Booster Dose

Dhanwani

Zhou

Huang

et al. 2016

Self Cite

Pichinde virus (PICV) is a bisegmented enveloped RNA virus that targets macrophages and dendritic cells (DCs) early in infection and induces strong innate and adaptive immunity in mice. We have developed a reverse genetics system to produce live recombinant PICV (strain P18) with a trisegmented RNA genome (rP18tri), which encodes all four PICV gene products and as many as two foreign genes. We have engineered the vector to express the green fluorescent protein (GFP) reporter gene (abbreviated as G in virus designations) and either the hemagglutination (HA [H]) or the nucleoprotein (NP [P]) gene of the influenza A/PR8 virus. The trisegmented viruses rP18tri-G/H and rP18tri-G/P showed slightly reduced growth in vitro and expressed HA and NP, respectively. Mice immunized with rP18tri-G/H were completely protected against lethal influenza virus challenge even 120 days after immunization. These rP18tri-based vectors could efficiently induce both neutralizing antibodies and antigen-specific T cell responses via different immunization routes. Interestingly, the immune responses were significantly increased upon a booster dose and remained at high levels even after three booster doses. In summary, we have developed a novel PICV-based live vaccine vector that can express foreign antigens to induce strong humoral and cell-mediated immunity and is ideal for a primeand-boost vaccination strategy. IMPORTANCE We have developed a novel Pichinde virus (PICV)-based live viral vector, rP18tri, that packages three RNA segments and encodes as many as two foreign genes. Using the influenza virus HA and NP genes as model antigens, we show that this rP18tri vector can induce strong humoral and cellular immunity via different immunization routes and can lead to protection in mice. Interestingly, a booster dose further enhances the immune responses, a feature that distinguishes this from other known live viral vectors. In summary, our study demonstrates a unique feature of this live rP18tri vector to be used as a novel vaccine platform for a prime-and-boost vaccination strategy.A renaviruses are enveloped RNA viruses with a bisegmented genome and mostly use rodents as natural hosts. There are at least 27 members that are geographically, serologically, and phylogenetically divided into Old World and New World arenaviruses (1). The prototypic lymphocytic choriomeningitis virus (LCMV) infection of mice has long been used as a valuable model with which to study viral persistence and virus-induced immunity and immunopathology (2, 3). The arenavirus is composed of a total of four genes on two genomic RNA segments in opposite orientations (1). The Z protein, produced from the large (L) genomic segment, is a small RING domain-containing matrix protein that mediates virus budding, regulates viral RNA synthesis, and mediates host immune suppression (4, 5). The large L protein (ϳ200 kDa), also encoded on the L segment, is the RNA-dependent RNA polymerase (RdRp), which is required for viral RNA synthesis (6). The glycoprotein (GPC), encoded...

“…Mutations in the SSP gene were created in the pCAGGS-PICV-GPC plasmid by overlapping PCR mutagenesis reactions, and the mutations were confirmed by sequencing. Plasmids used to rescue the PICV SSP mutant viruses were described previously (19). A plasmid that contains the T7 promoter-directed firefly luciferase gene was obtained from J. Nunberg (University of Montana, USA).…”

Section: Methodsmentioning

confidence: 99%

“…WT and SSP mutant viruses were rescued as previously described (19). The L plasmid together with the S plasmid containing either WT or mutant SSP was transfected into BSRT7-5 cells.…”

Section: F F L L L C G G R S C T M G Q I V T M F F E a L L P H I I I mentioning

confidence: 99%

“…A low-passaged strain of PICV (i.e., P2) causes a brief febrile reaction in guinea pigs, while a high-passaged strain (i.e., P18) causes a severe Lassa fever-like disease in guinea pigs with high mortality (3,(13)(14)(15)(16)(17). We have developed infectious clones for both the nonvirulent P2 strain and the virulent P18 strain of PICV (18) and characterized the virulence determinants at the molecular level (19)(20)(21).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Characterization of the Glycoprotein Stable Signal Peptide in Mediating Pichinde Virus Replication and Virulence

Shao

et al. 2016

Self Cite

Arenaviruses can cause lethal hemorrhagic fevers in humans with few preventative and therapeutic measures. The arenaviral glycoprotein stable signal peptide (SSP) is unique among signal peptides in that it is an integral component of the mature glycoprotein complex (GPC) and plays important roles not only in GPC expression and processing but also in the membrane fusion process during viral entry. Using the Pichinde virus (PICV) reverse genetics system, we analyzed the effects of alanine substitutions at many conserved residues within the SSP on viral replication in cell culture and in a guinea pig infection model. Our data showed that the K33A, F49A, and C57A mutations abolished GPC-mediated cell entry and therefore could not allow for the generation of viable recombinant viruses, demonstrating that these residues are essential for the PICV life cycle. The G2A mutation caused a marked reduction of cell entry at the membrane fusion step, and while this mutant virus was viable, it was significantly attenuated in vitro and in vivo. The N20A mutation also reduced membrane fusion activity and viral virulence in guinea pigs, but it did not significantly affect cell entry or viral growth in cell culture. Two other mutations (N37A and R55A) did not affect membrane fusion or viral growth in vitro but significantly reduced viral virulence in vivo. Taken together, our data suggest that the GPC SSP plays an essential role in mediating viral entry and also contributes to viral virulence in vivo. IMPORTANCESeveral arenaviruses, such as Lassa fever virus, can cause severe and lethal hemorrhagic fever diseases with high mortality and morbidity, and no FDA-approved vaccines or therapies are currently available. Viral entry into cells is mediated by arenavirus GPC that consists of an SSP, the receptor-binding GP1, and transmembrane GP2 protein subunits. Using a reverse genetics system of a prototypic arenavirus, Pichinde virus (PICV), we have shown for the first time in the context of virus infections of cell culture and of guinea pigs that the SSP plays an essential role in mediating the membrane fusion step as well as in other yet-to-be-determined processes during viral infection. Our study provides important insights into the biological roles of GPC SSP and implicates it as a good target for the development of antivirals against deadly human arenavirus pathogens.A renaviruses can cause neurologic or hemorrhagic fever diseases in humans, and few preventive or therapeutic measures are available (1, 2). The most significant arenavirus pathogen is Lassa fever virus (LASV), which causes infections that are endemic to many countries in West Africa, with an estimated 500,000 cases resulting in ϳ5,000 deaths annually (3). Except for Junin virus (JUNV), which has a vaccine, Candid#1, used only in Argentina, no licensed vaccine for human use is currently available for any other arenaviruses. Therapeutic options are limited and depend mainly on supportive care. Ribavirin, a nonspecific antiviral compound, has shown some efficacy ...