Coinfection with infectious precocity virus and Decapod iridescent virus 1 in farmed giant freshwater prawn (Macrobrachium rosenbergii)

In the past few years, outbreaks of infections with infectious precocious virus (IPV) and Decapod iridescent virus 1 (DIV1) have significantly hindered the development of the aquaculture industry of giant freshwater prawn (Macrobrachium rosenbergii) and caused severe economic losses in China. To understand the epidemiological information of farmed M. rosenbergii, we collected 79 samples from 23 farming ponds in Jiangsu Province from 2022 to 2023 and detected 8 common pathogens. The results showed that IPV and DIV1 could be detected in collected samples. Infections with IPV or DIV1 and the resulting diseases were confirmed by clinical signs, histopathologic examination, and qPCR. At the same time, we found coinfection with IPV and DIV1 in the same individuals by clinical diagnosis, histopathologic examination, and molecular testing. However, iron prawn syndrome (IPS) or IPS equivale and clinical infection with DIV1 (iDIV1) cases showed mutual exclusion in individuals and ponds. The results revealed significant differences in loads of the two viruses in the same individuals and ponds, with an overall negative correlation. This is the first report of coinfection with IPV and DIV1 in farmed M. rosenbergii.