Detection of the herpesviral hematopoietic necrosis disease agent (Cyprinid herpesvirus 2) in moribund and healthy goldfish: validation of a quantitative PCR diagnostic method

Abstract

Cyprinid herpesvirus 2 (CyHV-2) is a pathogen of goldfish Carassius auratus auratus L. that causes herpesviral hematopoietic necrosis (HVHN) disease. The disease is associated with necrosis of hematopoietic tissues and anemia with high mortality. We have developed a real time 5'-nuclease PCR method (Taqman) that quantitatively detects CyHV-2 with a linear response over 8 logs of target concentration. The coefficient of variability on replicate samples tested on different days was 13% and the calculated sensitivity approached 1 target molecule per reaction. The assay does not cross-react with other similar fish herpesviruses, including CyHV-1 (carp pox) and CyHV-3 (koi herpesvirus), but reliably detects known CyHV-2 positive fish. The assay detects CyHV-2 not just in clinical cases of HVHN but also in apparently healthy 1 yr old goldfish fingerlings and even in 3 to 5 yr old broodfish.

Establishment, characterization, and viral susceptibility of two cell lines derived from goldfish Carassius auratus muscle and swim bladder

“…Viral infections in goldfish have been reported in countries such as Japan, Australia, Taiwan, and the USA (Humphrey & Ashburner 1993, Jung & Miyazaki 1995, Arthington & McKenzie 1997, Goodwin et al 2006. Due to the size of viral particles and their intracellular replication, the effective identification and study of these microorganisms is largely dependent on the availability of sensitive cell lines.…”

Presence of herpesvírus in diseased fishes

“…These symptoms and signs have also been reported in fish infected by CyHV-2, CyHV-3 and IcHV, such as, Carassius auratus [33,19], Cyprinus carpio [17,36], Ictalurus punctatus [37,24] and Oreochromis aureus [22].…”

“…Studies around the world show a mortality rate of 80 to 100% in creations of carps infected by both CyHV-2 and CyHV-3 [16,17,18,19,20] as well by IcHV-1 that infects channel catfish [21], the 3 types of fish herpesvirus most frequent. Not yet know here in Brazil, which are the types of herpes viruses that are present in fish.…”

Is There Any Species Specificity in Infections with Aquatic Animal Herpesviruses?–The Koi Herpesvirus (KHV): An Alloherpesvirus Model

“…The cyprinid herpesvirus 1 (CyHV-1, carp pox virus) induced typical clinical signs in carp or koi (C. carpio), in golden ide (Leuciscus idus) [16] or in other cyprinids (carps and minnows) [17]. CyHV-2 or goldfish herpesvirus was first detected in goldfish (Carassius auratus), inducing severe disease outbreaks in those affected populations [18,19]. Recently severe outbreaks of disease with high mortalities were observed in crucian carp (Carassius carassius) [20] and Prussian carp (C. c. gibelio) [21] where CyHV-2 was identified as the disease causing agent.…”