Pichinde virus-induced respiratory failure due to obstruction of the small airways: structure and function

Characterization of virulence-associated determinants in the envelope glycoprotein of Pichinde virus

We use a small animal model, based on guinea pigs infected with a non-pathogenic Pichinde virus (PICV), to understand the virulence mechanisms of arenavirus infections in the hosts. PICV P2 strain causes a mild febrile reaction in guinea pigs, while P18 causes severe disease with clinical and pathological features reminiscent of Lassa hemorrhagic fever in humans. The envelope glycoproteins (GPC) of P2 and P18 viruses differ at positions 119, 140, and 164, all localized to the receptor-binding G1 subunit. We found that lentiviral pseudotyped virions (VLPs) bearing P18 GPC show more efficient cell entry than those with P2 GPC, and that the E140 residue plays a critical role in this process. Infection of guinea pigs with the recombinant viruses containing the E140K change demonstrated that E140 of GPC is a necessary virulence determinant of P18 infections, possibly by enhancing the ability of virus to enter target cells.

Hemorrhagic fever virus-induced changes in hemostasis and vascular biology

Viral hemorrhagic fever (VHF) denotes a virus-induced acute febrile, hemorrhagic disease reported from wide areas of the world. Hemorrhagic fever (HF) viruses are encapsulated, single-stranded RNA viruses that are associated with insect or rodent vectors whose interaction with humans defines the mode of disease transmission. There are 14 HF viruses, which belong to four viral families: Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae. This review presents, in order, the following aspects of VHF: (1) epidemiology, (2) anomalies of platelets and coagulation factors, (3) vasculopathy, (4) animal models of VHFs, (5) pathogenic mechanisms, and (6) treatment and future studies. HF viruses produce the manifestations of VHFs either by direct effects on cellular functions or by activation of immune and inflammatory pathways. In Lassa fever, Rift Valley fever and Crimean-Congo HF, the main feature of fatal illness appears to be impaired/delayed cellular immunity, which leads to unchecked viremia. However, in HF with renal syndrome and dengue HF, the immune response plays an active role in disease pathogenesis. The interplay of hemostasis, immune response, and inflammation is very complex. Molecular biologic techniques and the use of animal models have helped to unravel some of these interactions.