Phylogenetic analysis of tilapia lake virus (TiLV) isolates from the Philippines based on partial genome segment 3 sequences

Abstract

This study aimed to expand current knowledge on TiLV genetic diversity by sequence analysis of a portion of genome segment 3 of TiLV detected from the Philippines. This includes a recently deposited sequence in GenBank (Accession No. LC504279) and six new sequences from cases of infection reported from 2017 to 2020. Phylogenetic analysis of 179 bp fragment of segment 3 showed that the seven TiLV isolates from the Philippines can be divided into three phylogenetic groups. When comparing all sequences, unique nucleotide substitutions and amino acids were noted among these groups. Variation in mortality rates in naturally infected samples was also observed; however, poor environmental conditions during the disease outbreak may also contribute to the mortalities. These suggest the presence of at least three phylogenetic groups of TiLV in the Philippines which has significant implications for the future development of a vaccine, diagnostic kits, and genetic selection programs.