Differential effects of viral hemorrhagic septicaemia virus (VHSV) genotypes IVa and IVb on gill epithelial and spleen macrophage cell lines from rainbow trout (Oncorhynchus mykiss)

► VHSV genotype IVa isolate is more infectious to RTgill-W1 than one in genotype IVb. ► RTS11 aborted infection from VHSV isolates in genotype IVa and IVb. ► All six VHSV genes were expressed in RTS11 but no viral N protein detected. ► VHSV in genotype IVa and IVb differentially expressed host cells antiviral genes.