Serological Assays Based on Recombinant Viral Proteins for the Diagnosis of Arenavirus Hemorrhagic Fevers

Abstract

The family Arenaviridae, genus Arenavirus, consists of two phylogenetically independent groups: Old World (OW) and New World (NW) complexes. The Lassa and Lujo viruses in the OW complex and the Guanarito, Junin, Machupo, Sabia, and Chapare viruses in the NW complex cause viral hemorrhagic fever (VHF) in humans, leading to serious public health concerns. These viruses are also considered potential bioterrorism agents. Therefore, it is of great importance to detect these pathogens rapidly and specifically in order to minimize the risk and scale of arenavirus outbreaks. However, these arenaviruses are classified as BSL-4 pathogens, thus making it difficult to develop diagnostic techniques for these virus infections in institutes without BSL-4 facilities. To overcome these difficulties, antibody detection systems in the form of an enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescence assay were developed using recombinant nucleoproteins (rNPs) derived from these viruses. Furthermore, several antigen-detection assays were developed. For example, novel monoclonal antibodies (mAbs) to the rNPs of Lassa and Junin viruses were generated. Sandwich antigen-capture (Ag-capture) ELISAs using these mAbs as capture antibodies were developed and confirmed to be sensitive and specific for detecting the respective arenavirus NPs. These rNP-based assays were proposed to be useful not only for an etiological diagnosis of VHFs, but also for seroepidemiological studies on VHFs. We recently developed arenavirus neutralization assays using vesicular stomatitis virus (VSV)-based pseudotypes bearing arenavirus recombinant glycoproteins. The goal of this article is to review the recent advances in developing laboratory diagnostic assays based on recombinant viral proteins for the diagnosis of VHFs and epidemiological studies on the VHFs caused by arenaviruses.

Infecciones por arenavirus

“…No existen pruebas comerciales para arenavirus, solo los grupos de investigación especializados y grandes laboratorios de salud pública poseen pruebas de ELISA o IFI. Existe una importante reactividad cruzada entre los diferentes tipos de virus, por lo que el diagnóstico específico solo puede realizarse por medio de anticuerpos neutralizantes, los cuales aparecen entre 12 a 30 días del inicio de los síntomas y durante la convalecencia (6,32,33,34).…”

“…This technique implies direct contact with the virus, which is highly infecting, and therefore it must be carried out only in labs with category 4 biosecurity. During some years, specific RNA-PCR for arenavirus have been created which may be used in category three labs (6,32,33).…”

“…There are no commercial test for arenavirus, and only specialized research groups and public health laboratories have ELISA or IFI tests. There is an important crossreactivity between different types of viruses, and therefore the specific diagnosis can only be made with neutralizing antibodies, which appear between 12 and 30 days of symptom onset and during convalescence (6,32,33,34).…”

Development of a micro-neutralization assay for ebolaviruses using a replication-competent vesicular stomatitis hybrid virus and a quantitative PCR readout

“…Also, replicationcompetent VSV hybrid viruses can be generated that accommodate the envelope gene from various heterologous viruses and incorporate these envelopes into the VSV particle [14][15][16][17][18][19][20][21]. The cellular tropism of the VSV hybrid virus is now dictated by the new envelope, and neutralizing antibodies against the pathogenic virus neutralize the hybrid virus [22][23][24][25][26][27][28].…”

Laboratory Diagnosis of Lassa Fever

“…While the detection of a new positive IgG titer combined with an IgM response in the correct clinical setting may support a diagnosis of Lassa fever, the detection of a positive IgG response alone is insufficient to make a diagnosis. Lassa IgG titers may persist for decades (64), and seroprevalence studies in regions of endemicity have shown 4 to 55% of healthy individuals living in areas where the virus is endemic have detectable Lassa virus IgG titers (14,52,55,65,66).…”