Porcine macrophage-like cell line Cdelta2+ is susceptible to Japanese encephalitis virus infection

Authors: ADETUNJI, SHAKIRAT - Kansas State University; Smolensky, Dmitriy; Mitzel, Dana; Chitko-Mckown, Carol; CERNICCHIARO, NATALIA - Kansas State University; Noronha, Leela

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/17/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Objective: Japanese encephalitis virus (JEV) is a zoonotic arthropod-borne flavivirus that is a leading cause of severe neurologic infection in humans. Pigs have high titers and a lasting viremia upon natural infection making them important reservoirs of JEV. To date, the pathogenesis of JEV infection in pigs is poorly understood. Macrophages are commonly targeted by JEV, but primary macrophages are labor intensive to isolate, so we examined the susceptibility of an established porcine monocyte-derived macrophage-like cell line (Cdelta2+) to the attenuated JEV strain SA-14-14-2. Methods: Monolayers of Cdelta2+ and BHK-21 (positive control) cells were infected with SA-14-14-2 for 5 days at a multiplicity of infection (MOI) of 0.1. Culture supernatants and cells were collected at 0, 12, 24, 48, 72, 96, and 120 hours post infection (hpi), and monolayers were observed for cytopathic effects (CPE). The amount of infectious virus in supernatants was quantified using a standard plaque assay. Infected cells were stained with trypan blue to determine viability. An indirect immunofluorescence assay was used to detect the presence of JEV NS1 antigens. Results: Cdelta2+ cells were susceptible to SA-14-14-2 infection and produced infectious virus with a mean peak titer of 7 log10 pfu/ml, comparable to 7.6 log10 pfu/ml by BHK-21 cells which are hamster fibroblasts known to be vulnerable to JEV. Infected Cdelta2+ cells proliferated through 48 hpi, compared to 24 hpi for BHK, after which cell numbers and the proportion of viable cells declined. Infected Cdelta2+ and BHK cells also showed time-dependent CPE and intracellular localization of the JEV NS1 protein was observed at 24hpi. Conclusions: These findings demonstrate that the porcine macrophage cell line Cdelta2+ may be a relevant cell line for understanding JEV infection dynamics in a natural host species. These data provide a foundation to compare various JEV strains in vitro to allow for better understanding of host cell mechanisms critical for viral replication and maintenance in pigs, as well as a model for screening for potential therapeutic targets and mitigation strategies.