Intranasal immunization with CpG-B Oligodeoxynucleotides protects CBA mice from lethal equine herpesvirus 1 challenge

Equine herpesvirus 1 (EHV-1) is the causative agent of a number of equine pathological states, including severe disease of the central nervous system, respiratory infections, and abortion storms. Our results showed that intranasal immunization with CpG-B oligodeoxynucleotides (ODN) protects CBA mice from lethal EHV-1 challenge. IFN-γ and seven interferon-stimulated genes (ISGs) were upregulated 39.4- to 260.3-fold at 8 h postchallenge in the lungs of RacL11-challenged mice that had been immunized with CpG-B ODN. Treatment with 20 ng/ml of IFN-γ reduced EHV-1 yield by 100-fold in MH-S at 4 days post-VZV infection compared to that of untreated cells. However, IFN-γ reduced virus yield by only 2-fold in and mouse fibroblast L-M cells. To identify IFN-γ-stimulated genes that inhibit EHV-1 replication, Affymetrix microarray analyses were performed with IFN-γ-treated MH-S and L-M cells. In MH-S cells, IFN-γ upregulated 551 genes and down-regulated 136 genes as compared to those of untreated cells. In L-M cells, IFN-γ upregulated 225 genes and downregulated 2 genes. Nine genes associated with innate immune response were significantly upregulated only in MH-S cells. Five antiviral ISGs MX1, SAMHD1, NAMPT, TREX1, and DDX60 were upregulated 3.2- to 18.1-fold only in MH-S cells. These results suggest that CpG-B ODN may be used as a prophylactic agent in horses.

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Kim SK, Shakya AK, O'Callaghan DJ