Two Hyposoter didmator ichnovirus genes expressed in the lepidopteran host encode secreted or membrane-associated serine and threonine rich proteins in segments that may be nested

Abstract

We present in this work two novel Hyposoter didymator ichnovirus genes expressed in parasitized Spodoptera larvae. These genes, named HdC orfS6 and HdG orfP30, are unrelated and present in two different genome segments, possibly nested, SH-C and SH-G respectively. HdC orfS6 encodes a predicted transmembrane protein, putatively glycosylated. HdC orfS6 transcripts appear to be abundant in lepidopteran host hemocytes compared to the other tissues analyzed. The second gene described, HdG orfP30, is well expressed in hemocytes, but also in other tissues, such as the fat body, nervous system and epidermis. This gene is peculiar since it presents 17 perfectly conserved repeated sequences arranged in tandem arrays. Each of these repeats contains 58% of serine and threonine residues and therefore several potential sites for glycosylation. This mucin-like protein, predicted as highly glycosylated, could be involved in host immune suppression.