Isolation and characterization of koi herpesvirus (KHV) from Indonesia: identification of a new genetic lineage

Abstract

Koi herpesvirus (KHV) is the aetiological agent of an emerging disease (KHVD) associated with mass mortalities in koi and common carp and reported from at least 30 countries. We report the first isolation of KHV from koi and common carp in Indonesia and initial characterization of the isolates. Clinical signs, histopathology and virion morphology are similar to those of isolates from other countries. Phylogenetic analyses using the thymidine kinase gene amplified from each isolate and from carp tissue samples collected from KHVD outbreaks throughout Indonesia indicated that the Indonesian isolates are more closely related to the Asian than the European KHV lineage. Sequence analysis of two other variable regions between ORF29 and ORF31 (marker I) and near the start of ORF 133 (marker II) indicated that all Indonesian isolates displayed a marker I allele (I(++)) previously identified only in isolates of the Asian lineage. However, in the marker II region, all Indonesian isolates displayed the II(-) allele, which has been reported previously only amongst isolates of the European lineage, and nine of these displayed a mixed genotype (II(+)II(-)). The I(++)II(-) genotype has not been reported previously and appears to represent a new intermediate lineage that may have emerged in Indonesia.

First Report of Occurrences of Two Cyprinid Herpesvirus 3 Variants, I⁺⁺ II^− and I⁺⁺ II^+Δ, in China

“…Sunarto et al (2005) mentioned the first KHV infection case in Indonesia occurred among fish (Chen et al, 2014 , were identified from the 27 samples. Our data showed that the predominant genotype in Guangdong Province and Henan Province, China was I ++ II − , which has been reported to be widely distributed in Indonesia (Sunarto et al, 2011). This observation suggests that distribution of CyHV-3 in China has a close relationship with that in Southeast Asia.…”

“…Finally, two CyHV-3 isolates isolated from S14 and S17 samples were designated as ZS410 and HZ419, respectively. The KFC cells infected with ZS410 and HZ419 isolates and the tissue culture supernatant were collected and examined by transmission electronic microscopy (TEM) (Hitachi, Ltd.), according to the method described previously (Sunarto et al, 2011).…”

“…For example, the PCR product of marker I is a 168 bp fragment (I ++ ) in J strain, while the corresponding fragment is 130 bp in U/I strain (I −− ) due to the absence of two domains. (Sunarto et al, 2011).…”

“…In general, the first and second genotyping methods (Bigarré et al, 2009;Kurita et al, 2009) are preferentially chosen due to their simplicity for targeting 2 or 3 variable regions (Bigarré et al, 2009;Kurita et al, 2009;Sunarto et al, 2011;Kim and Kwon, 2013). To further improve the efficiency of duplex PCR for marker I/II, we optimized the approach with a newly designed nested-PCR.…”

Koi Herpes Virus: A Review and Risk Assessment of Indian Aquaculture

“…Hence, ORF136 can be also used as molecular marker to distinguish Asian isolates of KHV from European isolates. Recently, KHV from Indonesia is reconfirmed as new intermediate genotype between European and Asian genotypes [80].…”