The underlying mechanism of single and co-infection of DIV1 and WSSV in Litopenaeus vannamei

Abstract

Viral diseases are one of the important factors restricting the shrimp industry. Decapod iridescent virus 1 (DIV1) and White spot syndrome virus (WSSV) are the two most harmful viruses to shrimp. DIV1 and WSSV were found to be carried and infected simultaneously in several samples of cultured and wild shrimps. In this study, the co-infection model of DIV1 and WSSV in Litopenaeus vannamei was constructed by TaqMan probe quantitative detection (qPCR), intestinal section, and transcriptome analysis. Our study also evaluated the virulence of the virus by calculating LC50 and detected the replication rates of DIV1 and WSSV at 7-time points and 2 tissues in L. vannamei by qPCR. As a result, DIV1 and WSSV could infect L. vannamei singly or co-infect L. vannamei. DIV1 replicated the fastest, at 12–16 h post-injection (hpi). The WSSV virus replicates the fastest 20–24 hpi. In different tissues, the amount of DIV1 carried by blood cells is higher than that in muscle, while WSSV is the opposite. In addition, the intestinal responses of DIV1 and WSSV single and co-infection of L. vannamei were explored using the RNA-Seq platform and bioinformatics analysis, and the differential expressed genes (DEGs) screened by comparison were as follows: there were significant differences in DEGs between the PBS group and the three virus infection groups, and there were differences in DEGs between the PBS group and single virus infection groups (the DIV1 group and the WSSV group), but there was no significant difference in the DEGs between the 2 single virus infection groups, and the Combine-infected group, especially, the DEGs between the WSSV group and the Combine-infected group were only 39. According to the above conclusions, it can be inferred that WSSV plays a major role in co-infection. In addition, pathways related to vitamin metabolism were significantly enriched in the viral infection group compared to the PBS group. Glycolysis/Gluconeogenesis, a hallmark of the Warburg effect, is also significantly enriched after viral infection. In this study, the co-infection phenomenon of DIV1 and WSSV was found for the first time in L. vannamei, which provided a new idea for developing and screening molecular markers for new strains resistant to complex viruses in L. vannamei.