Nidoviral infections of fish and prawn: a review

Purpose. Nidoviruses are wide spread pathogens of animals and humans. The order Nidovirales covers enveloped viruses with one segment of linear positive-sense single-stranded RNA. The order comprises four families including Coronaviridae, Arteriviridae, Roniviridae and Mesoniviridae. Despite numerous studies, Nidoviruses remain poorly understood today. The complexity of replication mechanisms and significant differences in genome size of individual families are the main problem to understand the life cycle of these viruses. Therefore, we tried to analyze the array of special literature data and summarize the information obtained on nidoviral infections of fish and prawns, structural and functional properties of the Nidovirales members, and the symptoms and consequences of diseases caused by them. Findings. The presented data contain a brief analytical summary of viruses from the Nidovirales order, which infect fish and prawns. The current classification of water nidoviruses is noted. The morphological and genetic structure of fish nidoviruses as well as the known mechanisms of their replication and other functional properties are shown. Particular attention is paid to the description of symptoms and routes of nidovirus infection development in aquatic organisms. However, effective prevention and treatment of nidoviral infections is unknown. Currently, significant number of nidoviruses is insufficiently studied: partially or completely remain uncharacterized mechanisms of replication, genomic structure, the interactions with environment condition and virus spread, etc. Practical Value. The review may be useful for scientists studying representatives of Nidovirales order and problems associated with diseases caused by these viruses. The description of disease symptoms will help in preliminary diagnosis of nidoviral infections in fish and prawns and raise awareness concerning its possible negative impact on aquaculture. Further development of knowledge about the morphological and molecular biological properties of nidoviruses, as well as the study of disease symptoms in aquatic organisms is promising direction for both purely biological aspects and for sustainable aquaculture.