Complete Genome Sequence of an Ictalurid Herpesvirus 1 Strain Isolated from Blue Catfish (<named-content content-type='genus-species'>Ictalurus furcatus</named-content>)

The complete genome sequence of an alloherpesvirus isolated from blue catfish (Ictalurus furcatus) is reported. Genomic analyses revealed that this virus is a distinct strain of ictalurid herpesvirus 1, the first strain of which was isolated previously from a channel catfish (Ictalurus punctatus). Ictalurid herpesvirus 1 (IcHV1) is classified in the species Ictalurid herpesvirus 1, genus Ictalurivirus, and was the first member of the family Alloherpesviridae to be sequenced (1). This virus causes acute mortality in young channel catfish (Ictalurus punctatus). Blue catfish (Ictalurus furcatus) are related closely to channel catfish, and channel blue catfish hybrids are becoming increasingly popular in U.S. aquaculture. In 1998, a population of blue catfish fingerlings reared in an earthen pond exhibited clinical signs like those caused by IcHV1. Moreover, a virus referred to as blue catfish alloherpesvirus (BCAHV) was isolated in the channel catfish ovary (CCO) cell line (ATCC CRL-2772) and exhibited cytopathic effects like those of IcHV1. The partial nucleotide sequence of the gene encoding the DNA polymerase catalytic subunit showed the highest identity (98%, 428/438) to IcHV1 (2). Clarified CCO cell lysate was centrifuged at 20,000 g for 30 min, and DNA was isolated from the pellet using a Gentra Puregene tissue kit (Qiagen). A DNA sequencing library was prepared using a Nextera XT kit (Illumina) and sequenced on a MiSeq (Illumina) instrument using a v3 600-cycle kit. The 2,027,408 reads were depleted of host (Ictalurus punctatus) sequences (GenBank accession no. LBML00000000) using Kraken v2.0 (3) with default parameters. De novo assembly of the resulting 1,955,567 reads using SPAdes 3.11 (4) with default settings generated two contigs closely related to the IcHV1 Auburn strain sequence (GenBank accession no. M75136). These contigs were joined into a genome sequence by manually incorporating reads at their ends until they overlapped. The genome termini were identified from large sets of reads commencing at the same positions. The integrity of the sequence was verified by mapping the reads using Bowtie 2.1. 0 (5) and inspecting the alignment in Tablet 1.17. 08.17 (6) with default settings. The average coverage was 3,883 reads/nucleotide. The linear BCAHV genome (134,493 bp) consists of a unique region (97,333 bp) flanked by terminal direct repeats (18,580 bp). A total of 91 protein-coding open reading frames (ORFs) were predicted, with 63 in the unique region and 14 in each terminal repeat. These ORFs were identified initially by transferring the IcHV1 annotations to the BCAHV genome using GATU (https://4virology.net/virology-ca-tools/gatu/) with default settings. The annotation was improved by comparisons with other memCitation Subramaniam K, Venugopalan A, Davison AJ, Griffin MJ, Ford L, Waltzek TB, Hanson L. 2019. Complete genome sequence of an ictalurid herpesvirus 1 strain isolated from blue catfish (Ictalurus furcatus). Microbiol Resour Announc 8:e00082-19. https://doi.org/ 10.1128/MRA.00082-19. Editor Frank J. Stewart, Georgia Institute of Technology Copyright © 2019 Subramaniam et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Address correspondence to Larry Hanson, hanson@cvm.msstate. edu. Received 23 January 2019 Accepted 15 March 2019 Published 11 April 2019 GENOME SEQUENCES