Rivers’s Postulates Fulfilled for Blue Catfish Alloherpesvirus

Vandana Dharan,Suja Aarattuthodiyil

doi:10.11648/j.fem.20210703.12

Abstract

Blue catfish alloherpesvirus (BCAHV) is a strain of ictalurid herpesvirus-1 belonging to the family Alloherpesviridae. A detailed study on the pathogenesis of this virus revealed that it causes significant mortalities in blue catfish fingerlings and could be problematic with hybrid catfish production. The genome of BCAHV has 94% similarity with channel catfish virus (CCV) and these herpesviruses are a major threat to the hatchery and nursery phases of fish production. Even though, several studies have been caried out regarding the virulence, immune responses, and factors influencing infection, Rivers’s postulates have not been verified for BCAHV infection so far. Validation of Rivers’s postulates is essential to confirm virus as the causative agent of a disease. Testing and verification of Rivers’s postulates are also essential to decide on treatments or while establishing proactive management strategies. In the current study, we tested Rivers’s postulates to validate BCAHV as the etiologic agent of the infection in blue catfish fingerlings. The infected blue catfish tissues were processed, filtered, inoculated onto channel catfish ovary (CCO) cells, and virus-specific cytopathic effects were observed. The cell culture propagated-BCAHV produced comparable infection in naïve blue catfish when exposed via immersion and was reisolated from the infected fish. Specific immune responses against BCAHV were observed, when survivors from an initial virus exposure were challenged with wild type virus after 45 days. Here, Rivers’s postulates were satisfied for BCHAV infection in blue catfish proving BCAHV as the etiological agent of infection.

Highlights

Infectious viral diseases are detrimental to intensive aquaculture production and result in substantial economic and trade losses hindering the expansion of global aquaculture [1]
Dmitri Ivanovsky in 1892 reported the first viral disease in tobacco plants, which remained obscure until Martinus Beijerinck in 1898 described the causative agent as tobacco mosaic virus [8]
Since viruses require host cells for replication, viral disease diagnosis relied on susceptible cell cultures as early as 1900s [10,11]

Summary

Introduction

Infectious viral diseases are detrimental to intensive aquaculture production and result in substantial economic and trade losses hindering the expansion of global aquaculture [1]. Some of the viral infections enlisted by the World Organization for Animal Health (OIE) are required to be reported to state animal health officials [2,3,4]. In such cases, the producer has to destroy the entire infected stock and disinfect the farm/hatchery further exacerbating the financial losses. Viruses are obligate intracellular parasites that require host cell machinery to propagate and cause infections [6,7]. These submicroscopic infectious agents can infect all life forms from bacteria to higher vertebrates. Cell cultures are considered as the ‘gold standard’ in virology [11, 12]

Methods

Results

Conclusion