African swine fever virus does not express viral microRNAs in experimentally infected pigs

Abstract

BackgroundAfrican swine fever virus (ASFV) is the etiological agent of African swine fever (ASF), a re-expanding devastating and highly lethal hemorrhagic viral disease. microRNAs (miRNAs) are a new class of small non-coding RNAs that regulate gene expression post-transcriptionally. The discovery of virus specific miRNAs has increased both in number and importance in the past few years. We have recently described the differential expression of several porcine miRNAs during in vivo infection with attenuated and virulent ASFV strains. Here, we have extended these studies trying to identify the presence of viral miRNAs encoded by ASFV in an in vivo infection in pigs.ResultsSixteen small RNA libraries were analyzed from spleen and submandibular lymph nodes obtained from eight pigs, seven infected with either the virulent E75 ASFV strain or its attenuated counterpart E75CV1, or from pigs surviving E75CV1-infection and challenged with BA71 (heterologous challenge) and one non infected as negative control. Samples were recovered at different times post-infection. Libraries were analyzed by next-generation sequencing. Some viral miRNA candidates were initially identified, which did not correspond to porcine miRNAs. Further structural analyses were carried out in order to confirm if they met the conformational requirements to be considered a viral miRNA.ConclusionsThe analysis of sixteen small RNA libraries prepared from two different tissues obtained from pigs experimentally infected with E75, E75CV1 or with E75CV1 plus BA71, revealed the presence of six potential miRNA sequences but none of them met the requirements to be considered as viral miRNAs. Thus, we can conclude that ASFV does not express miRNAs in vivo, at least under the experimental conditions described here.

Identification of a Functional Small Noncoding RNA of African Swine Fever Virus

“…7a to c ). A previous in vivo study concluded that ASFV does not express viral miRNAs in experimentally infected pigs ( 31 ). However, the previous study restricted its analysis to miRNA only based on predictions of precursor miRNA structures and did not consider other classes of sncRNA.…”

“…These authors identified 12 miRNAs that were differentially expressed. In addition, a further study looked in vivo at the potential for ASFV to encode its own miRNAs and concluded that ASFV does not express miRNAs in vivo ( 31 ). In our study, we investigated the effect of ASFV infection on sncRNA in primary porcine alveolar macrophages in vitro .…”

Toosendanin suppresses African swine fever virus replication through upregulating interferon regulatory factor 1 in porcine alveolar macrophage cultures

“…The obtained cDNAs or extracted DNA were used as templates for RT-qPCR and qPCR, respectively, on a CFX96 real-time polymerase chain reaction system (Bio-Rad, Hercules, CA, United States) using 2 × RealStar Green Power Mixture (containing SYBR Green I Dye; Genstar, Beijing, China). The primers used for determining the DNA level of ASFV replication by using p72 gene ( Nunez-Hernandez et al, 2018 ) were listed in Table 1 . The primers ( Arabyan et al, 2018 ) used for determining the mRNA level of ASFV replication by using the p72 and p30 genes were listed in Table 2 .…”

MicroRNAs as Biomarkers for Animal Health and Welfare in Livestock

“…The putative target genes were related to immune responses, such as B and T cell receptor signaling pathways, natural killer cell-mediated cytotoxicity, or Fc gamma R-mediated phagocytosis, as well as with processes related to infection-related pathogenesis and virus-host interaction (131). In another in vivo study, the same authors assessed the potential for ASFV to encode its own miRNAs, with negative results (132).…”