Chikungunya virus (CHIKV), an arthritogenic old-world alphavirus, has been implicated in the central nervous system (CNS) infection in infants and elderly patients. Astrocytes are the major immune cells of the brain parenchyma that mediate inflammation. In the present study we found that a local isolate of CHIKV infect and activate U-87 MG cells, a glioblastoma cell line of human astrocyte origin. The infection kinetics were similar in infected U-87 MG cells and the human embryo kidney (HEK293) cells as indicated by immunofluorescence and plaque assays, 24h post-infection (p.i.). In infected U-87 MG cells, apoptosis was detectable from 48h p.i. evidenced by DNA fragmentation, PARP cleavage, loss of mitochondrial membrane potential, nuclear condensation and visible cytopathic effects in a dose and time-dependent manner. XBP1 mRNA splicing and eIF2α phosphorylation studies indicated the occurrence of endoplasmic reticulum stress in infected cells. In U-87 MG cells stably expressing a green fluorescent protein-tagged light chain-3 (GFP-LC3) protein, CHIKV infection showed increased autophagy response. The infection led to an enhanced expression of the mRNA transcripts of the pro-inflammatory cytokines IL-1β, TNF-α, IL-6 and CXCL9 within 24h p.i. Significant up-regulation of the proteins of RIG-I like receptor (RLR) pathway, such as RIG-I and TRAF-6, was observed indicating the activation of the cytoplasmic-cellular innate immune response. The overall results show that the U-87 MG cell line is a potential in vitro model for in depth study of these molecular pathways in response to CHIKV infection. The responses in these cells of CNS origin, which are inherently defective in Type I interferon response, could be analogous to that occurring in infants and very old patients who also have a compromised interferon-response. The results also point to the intriguing possibility of using this virus for studies to develop oncolytic virus therapy approaches against glioblastoma, a highly aggressive malignancy.

Metagenomic sequencing of three nasal swabs collected from 10- to 21-day-old pigs exhibiting unexplained acute respiratory disease from two different commercial production facilities in Oklahoma identified a novel genotype of porcine astrovirus 4 (PAstV-4). The genomes had only ~75 % nucleotide sequence identity to previously characterized PAstV-4 isolates, while the capsid-encoding ORF2 had only ~53 % amino acid sequence identity to reference strains. A TaqMan assay targeting the novel ORF2 gene found 21 % and 19 % incidence in nasal and fecal swabs, respectively, submitted for unrelated diagnostic testing. PAstV-4 RNA levels were significantly higher (P = 0.04) in nasal swabs, suggesting a possible atypical respiratory tropism.

Feral swine are known reservoirs for various pathogens that can adversely affect domestic animals. To assess the viral ecology of feral swine in the USA, metagenomic sequencing was performed on 100 pooled nasal swabs. The virome was dominated by small, ssDNA viruses belonging to the families Circoviridae, Anelloviridae and Parvovirinae. Only four RNA viruses were identified: porcine kobuvirus, porcine sapelovirus, atypical porcine pestivirus and a novel Orthopneumovirus, provisionally named swine orthopneumovirus (SOV). SOV shared~90 % nucleotide identity to murine pneumonia virus (MPV) and canine pneumovirus. A modified, commercially available ELISA for MPV found that approximately 30 % of both feral and domestic swine sera were positive for antibodies cross-reactive with MPV. Quantitative reverse transcription-PCR identified two (2 %) and four (5.0 %) positive nasal swab pools from feral and domestic swine, respectively, confirming that SOV circulates in both herds.

No abstract

Research in the field of hydrogels has been actively growing for the past couple of decades. Hydrogels are crosslinked polymers with high water content. They can be prepared from natural, synthetic, and composite polymers using different chemical and physical crosslinking methods. Hydrogels have been widely explored for the delivery of bioactive molecules, drugs, and for other therapeutic applications. Chitosan-based hydrogels have unique advantages owing to their biocompatibility, biodegradability, antimicrobial activity, mucoadhesivity, and low toxicity. This chapter reviews the different methods used for preparing chitosan-based hydrogels and their applications as cell, protein, and drug delivery vehicles to support tissue regeneration.