A CASE STUDY OF LYMPHOCYSTIS VIRUS DISEASE IN FARMED GIANT SNAKEHEAD (Channa striata) IN MANDIANGIN, SOUTH KALIMANTAN

Lymphocystis virus has been implicated as the cause of severe infection, mortality, and economic loss in farmed giant snakehead (Channa striata) or gabus fish in Mandiangin South Kalimantan. In Kalimantan, the fish is locally known as Haruan fish and considered to have health-related benefits to human due to its high albumin content. This study aimed to determine the LCDV in gabus fish through histopathological and PCR investigation. Infected LCDV fish have a cluster of warts growths in the skin or fin of a walleye. Infected fishes with an average of total length of 15 cm and weight of 150 g were collected from local net cages and earthen ponds. They were transferred into a laboratory, anesthetized, and then subsequently killed by organ dissection. The infected fish tumors were aseptically cut out for histological study and PCR detection. Primer used was forward GII F: 5 ‘TGG GAT TCC AAY GGT CAA TTA-3’ with target band of 468 bp (for genotype-IIi LCDV) and primer reverse R: 5’TTA GAT TAT TGG GCA GCG TT-3' with target band of 250 bp (for genotype-II LCDV) and GIII F: 5' AGG AAA TAA CCG CAG TA GAA TGCA. Lymphocytosis in infected fish showed multifocal to diffuse white, round, firm, papilloma or tumor-like nodules on the skin of the body, fins, eyes, and mouth. The hypertrophied cell was surrounded by a thick smooth hyaline capsule. Stress condition caused by high population density, nutrition deficiencies, decreased dissolved oxygen, suboptimal water quality, and handling may increase the appearance of LCDV symptoms. The result of the present study revealed that histopathology and PCR could be used to diagnose LCDV infection

The genome sequence of the emerging common midwife toad virus identifies an evolutionary intermediate within ranaviruses

Worldwide amphibian population declines have been ascribed to global warming, increasing pollution levels, and other factors directly related to human activities. These factors may additionally be favoring the emergence of novel pathogens. In this report, we have determined the complete genome sequence of the emerging common midwife toad ranavirus (CMTV), which has caused fatal disease in several amphibian species across Europe. Phylogenetic and gene content analyses of the first complete genomic sequence from a ranavirus isolated in Europe show that CMTV is an amphibian-like ranavirus (ALRV). However, the CMTV genome structure is novel and represents an intermediate evolutionary stage between the two previously described ALRV groups. We find that CMTV clusters with several other ranaviruses isolated from different hosts and locations which might also be included in this novel ranavirus group. This work sheds light on the phylogenetic relationships within this complex group of emerging, disease-causing viruses. © 2012, American Society for Microbiology.Peer Reviewe

The genome sequence of the emerging common midwife toad virus identifies an evolutionary intermediate within ranaviruses

Worldwide amphibian population declines have been ascribed to global warming, increasing pollution levels, and other factors directly related to human activities. These factors may additionally be favoring the emergence of novel pathogens. In this report, we have determined the complete genome sequence of the emerging common midwife toad ranavirus (CMTV), which has caused fatal disease in several amphibian species across Europe. Phylogenetic and gene content analyses of the first complete genomic sequence from a ranavirus isolated in Europe show that CMTV is an amphibian-like ranavirus (ALRV). However, the CMTV genome structure is novel and represents an intermediate evolutionary stage between the two previously described ALRV groups. We find that CMTV clusters with several other ranaviruses isolated from different hosts and locations which might also be included in this novel ranavirus group. This work sheds light on the phylogenetic relationships within this complex group of emerging, disease-causing viruses.This work was supported by grant AGL 2009-08711 from the Spanish Ministerio de Ciencia e Innovación. Alberto López-Bueno and Carla Mavián are recipients of the Ramón y Cajal and Formación del Personal Investigador fellowships, respectively, from the same institutio

Comparative genomic analysis of the family Iridoviridae: re-annotating and defining the core set of iridovirus genes

BACKGROUND: Members of the family Iridoviridae can cause severe diseases resulting in significant economic and environmental losses. Very little is known about how iridoviruses cause disease in their host. In the present study, we describe the re-analysis of the Iridoviridae family of complex DNA viruses using a variety of comparative genomic tools to yield a greater consensus among the annotated sequences of its members. RESULTS: A series of genomic sequence comparisons were made among, and between the Ranavirus and Megalocytivirus genera in order to identify novel conserved ORFs. Of these two genera, the Megalocytivirus genomes required the greatest number of altered annotations. Prior to our re-analysis, the Megalocytivirus species orange-spotted grouper iridovirus and rock bream iridovirus shared 99% sequence identity, but only 82 out of 118 potential ORFs were annotated; in contrast, we predict that these species share an identical complement of genes. These annotation changes allowed the redefinition of the group of core genes shared by all iridoviruses. Seven new core genes were identified, bringing the total number to 26. CONCLUSION: Our re-analysis of genomes within the Iridoviridae family provides a unifying framework to understand the biology of these viruses. Further re-defining the core set of iridovirus genes will continue to lead us to a better understanding of the phylogenetic relationships between individual iridoviruses as well as giving us a much deeper understanding of iridovirus replication. In addition, this analysis will provide a better framework for characterizing and annotating currently unclassified iridoviruses