Validation of Edwardsiella ictaluri oral vaccination platform in experimental pond trials

Abstract

Since its recognition in the early 1980s, enteric septicemia of catfish (ESC), caused by the gram-negative enteric Edwardsiella ictaluri, is one of the most significant pathogens affecting catfish aquaculture. In efforts to improve disease management in U.S. catfish aquaculture, a live-attenuated ESC vaccine and method of in-pond oral vaccine delivery was developed. This work evaluated the efficacy of the oral delivery platform using a live-attenuated E. ictaluri vaccine under simulated commercial conditions. Channel catfish fingerlings were orally vaccinated approximately 40-50 days poststocking by mixing the attenuated vaccine with feed using a patent-pending mechanized delivery system. Across three discrete years under varying evaluation methods, vaccination resulted in significant improvements in survival, feed conversion ratio, feed fed, and total yield. An economic analysis of experimental data suggests a significant positive net economic benefit from vaccination.After accounting for a projected cost of vaccination, the realized improvements in survival and yield resulted in an estimated benefit exceeding $3,500/ha ($1,400/acre) on fingerling operations. These results suggest vaccinating channel catfish fingerlings against ESC is an effective strategy to mitigate ESC-related losses and can significantly improve production efficiency and profitability on catfish operations.

Bioeconomic Analysis of Flavobacterium columnare Vaccine Pond Trials with Channel Catfish

“…Trends from previous E . ictaluri vaccine trials coincide with our production data by demonstrating that vaccination markedly improved the FCR (Wise et al 2015, 2019; Kumar et al 2019). However, our trial involved the vaccination of older fingerlings, which have a decreased feed conversion efficiency compared to fry due to body size and age (Robinson and Li 2015).…”

A Review of Bacterial Co-Infections in Farmed Catfish: Components, Diagnostics, and Treatment Directions

“…Transmission occurs once an infected fish sheds the pathogen, thus allowing surrounding fish to ingest E. ictaluri [ 10 ]. Although all ages of catfish can experience ESC, channel catfish fingerlings are most susceptible to post-hatch losses due to disease typically arising from ESC [ 11 ]. ESC survivors possess immunity to the disease, rendering older catfish more resistant to reinfection.…”

“…Other methods include restricting feed to the catfish while temperatures are within ESC’s optimal growth range. However, this method also has some limitations as this management strategy can reduce the growth of catfish during production [ 11 ]. Recently, several investigations aimed to discern mechanisms of virulence for E. ictaluri .…”

“…The development and introduction of ESC vaccines have proven to decrease infection rates, but it does not eliminate infection threats. Typically, ESC vaccines were administered through immersion baths on catfish fry [ 11 ]. However, this method may not be the most effective as fry may not be immunocompetent.…”

Technological progress in the US catfish industry

“…Recent development of an ESC‐vaccination platform (Wise, Greenway, & Byars, 2015) has allowed for the measured delivery of an effective live attenuated vaccine (Aarattuthodiyil et al, 2020; Greenway et al, 2017; Griffin et al, 2020) to immunocompetent fingerlings in commercial pond settings. This one‐time, feed‐based vaccination protocol has been proven economical in controlling ESC in both channel and hybrid catfish under commercial fingerling production settings (Kumar et al, 2019; Wise et al, 2020). Its use on catfish fingerling farms has increased since it became available commercially in 2018.…”