title: A 2.5-kilobase deletion containing a cluster of nine microRNAs in the latency-associated-transcript locus of the pseudorabies virus affects the host response of porcine trigeminal ganglia during established latency.
abstract: The alphaherpesvirus pseudorabies virus (PrV) establishes latency primarily in neurons of trigeminal ganglia when only the transcription of the latency-associated transcript (LAT) locus is detected. Eleven microRNAs (miRNAs) cluster within the LAT, suggesting a role in establishment and/or maintenance of latency. We generated a mutant (M) PrV deleted of nine miRNA genes which displayed properties that were almost identical to those of the parental PrV wild type (WT) during propagation in vitro. Fifteen pigs were experimentally infected with either WT or M virus or were mock infected. Similar levels of virus excretion and host antibody response were observed in all infected animals. At 62 days postinfection, trigeminal ganglia were excised and profiled by deep sequencing and quantitative RT-PCR. Latency was established in all infected animals without evidence of viral reactivation, demonstrating that miRNAs are not essential for this process. Lower levels of the large latency transcript (LLT) were found in ganglia infected by M PrV than in those infected by WT PrV. All PrV miRNAs were expressed, with highest expression observed for prv-miR-LLT1, prv-miR-LLT2 (in WT ganglia), and prv-miR-LLT10 (in both WT and M ganglia). No evidence of differentially expressed porcine miRNAs was found. Fifty-four porcine genes were differentially expressed between WT, M, and control ganglia. Both viruses triggered a strong host immune response, but in M ganglia gene upregulation was prevalent. Pathway analyses indicated that several biofunctions, including those related to cell-mediated immune response and the migration of dendritic cells, were impaired in M ganglia. These findings are consistent with a function of the LAT locus in the modulation of host response for maintaining a latent state.
  
  
  OBJECTIVE
  This study provides a thorough reference on the establishment of latency by PrV in its natural host, the pig. Our results corroborate the evidence obtained from the study of several LAT mutants of other alphaherpesviruses encoding miRNAs from their LAT regions. Neither PrV miRNA expression nor high LLT expression levels are essential to achieve latency in trigeminal ganglia. Once latency is established by PrV, the only remarkable differences are found in the pattern of host response. This indicates that, as in herpes simplex virus, LAT functions as an immune evasion locus.
authors.affiliation: INRA, AgroParisTech, UMR1313 Animal Genetics and Integrative Biology, Jouy-en-Josas, France CEA, DSV, IRCM, SREIT, LREG, Jouy-en-Josas, France.
authors.forename: Nada
authors.initials: N
authors.lastname: Mahjoub
authors.affiliation: INRA, AgroParisTech, UMR1313 Animal Genetics and Integrative Biology, Jouy-en-Josas, France CEA, DSV, IRCM, SREIT, LREG, Jouy-en-Josas, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Dhorne-Pollet
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Fuchs
authors.affiliation: INRA, AgroParisTech, UMR1313 Animal Genetics and Integrative Biology, Jouy-en-Josas, France CEA, DSV, IRCM, SREIT, LREG, Jouy-en-Josas, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Endale Ahanda
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Lange
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Klupp
authors.affiliation: INRA, AgroParisTech, UMR1313 Animal Genetics and Integrative Biology, Jouy-en-Josas, France CEA, DSV, IRCM, SREIT, LREG, Jouy-en-Josas, France.
authors.forename: Anoop
authors.initials: A
authors.lastname: Arya
authors.affiliation: Computational Genomics, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Loveland
authors.affiliation: INRA, Molecular Immunology and Virology Unit, Jouy-en-Josas, France.
authors.forename: François
authors.initials: F
authors.lastname: Lefevre
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Mettenleiter
authors.affiliation: INRA, AgroParisTech, UMR1313 Animal Genetics and Integrative Biology, Jouy-en-Josas, France CEA, DSV, IRCM, SREIT, LREG, Jouy-en-Josas, France elisabetta.giuffra@jouy.inra.fr.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Giuffra
mesh_terms: D000818:Animals; D020869:Gene Expression Profiling; D011558:Herpesvirus 1, Suid / Q000276:immunology / Q000502:physiology*; D054884:Host-Pathogen Interactions; D007111:Immunity, Cellular; D035683:MicroRNAs; D011557:Pseudorabies / Q000276:immunology* / Q000821:virology*; D017384:Sequence Deletion; D013552:Swine; D012668:Trigeminal Ganglion / Q000276:immunology* / Q000821:virology*; D017735:Virus Latency; D014779:Virus Replication
chemical_list: D035683:MicroRNAs