Virulent infection of outbred Hartley guinea pigs with recombinant Pichinde virus as a surrogate small animal model for human Lassa fever

Abstract

Arenaviruses, such as Lassa virus (LASV), can cause severe and fatal hemorrhagic fevers (e.g., Lassa fever, LF) in humans with no vaccines or therapeutics. Research on arenavirus-induced hemorrhagic fevers (AHFs) has been hampered by the highly virulent nature of these viral pathogens, which require high biocontainment laboratory, and the lack of an immune-competent small animal model that can recapitulate AHF disease and pathological features. Guinea pig infected with Pichinde virus (PICV), an arenavirus that does not cause disease in humans, has been established as a convenient surrogate animal model for AHFs as it can be handled in a conventional laboratory. The PICV strain P18, derived from sequential passaging of the virus 18 times in strain 13 inbred guinea pigs, causes severe febrile illness in guinea pigs that is reminiscent of lethal LF in humans. As inbred guinea pigs are not readily available and are difficult to maintain, outbred Hartley guinea pigs have been used but they show a high degree of disease heterogeneity upon virulent P18 PICV infection. Here, we describe an improved outbred guineapig infection model using recombinant rP18 PICV generated by reverse genetics technique followed by plaque purification, which consistently shows >90% mortality and virulent infection. Comprehensive virological, histopathological, and immunohistochemical analyses of the rP18virus infected animals show similar features of human LASV infection. Our data demonstrate that this improved animal model can serve as a safe, affordable, and convenient surrogate small animal model for studying human LF pathogenesis and for evaluating efficacy of preventative or therapeutic approaches.

RIG-I and MDA5 Protect Mice From Pichinde Virus Infection by Controlling Viral Replication and Regulating Immune Responses to the Infection

“…To establish a timeline of rPICV replication in mice and to examine the possible connectivity between morbidity and the levels of viral replication, mice infected with WT rPICV were sacrificed at various timepoints post infection to determine infectious viral titers in the spleen, serum, and liver by plaque assay. As previously observed in rPICV-infected guinea pigs ( 24 , 25 , 38 ), rPICV viral titer was highest in the spleen at day 3 post infection, which is thought to be due to the circulating monocytes trafficking into the draining lymph nodes being among the earliest targets of mammarenaviral infections ( 39 , 40 ). Splenic virus titers were higher for the SKO and DKO mice as compared to the WT mice by several logs at day 3 post infection ( Figure 2A ) and were also significantly higher for both KO mouse lines in the liver ( Figure 2B ) and for the DKO mice in the serum ( Figure 2C ) at day 3 post infection.…”

“…Pichinde virus (PICV), which is a NW BSL2-level mammarenavirus that normally does not cause disease in humans or mice but has been adapted for use in guinea pigs as a surrogate model of Lassa fever ( 24 , 25 ). It adopts a life cycle like that of other mammarenaviruses.…”

“…While the host tropism of PICV has not been fully determined, the virus has been shown to infect both guinea pigs and mice as well as cells from several other species, including African green monkey (Vero) ( 30 ), hamster (BHK-21) ( 30 ) and human (PBMCs and THP1) ( 31 ). While the tissue tropism within mice and guinea pigs can be quite diverse, infectious virus and pathology mediated by virus infection can be found systemically in guinea pigs ( 25 ) and suckling mice ( 32 , 33 ).…”

Understanding Immune Responses to Lassa Virus Infection and to Its Candidate Vaccines

“…In addition to animal models for use with LASV, several surrogate models of LF have been developed with LCMV and Pichinde virus (PICV) to circumvent BSL4 containment needs [ 141 , 142 ]. The WE strain of LCMV can cause lethal disease in rhesus macaques if given intravenously.…”

Pathogenicity and virulence mechanisms of Lassa virus and its animal modeling, diagnostic, prophylactic, and therapeutic developments

“…The use of NHPs in LF research, therefore, is hindered by the available numbers of the animal, high maintenance costs, and ethical concerns pertaining to their use. Due to these reasons, surrogate models of LF have been developed, including infection of small animals with Pichinde virus (PICV) [ 132 , 133 ] and LCMV, which have recently been reviewed elsewhere [ 79 ].…”