DIFFERENTIAL GLYCOSYLATION OF THE ECTODOMAIN OF THE PRIMARY ENVELOPE GLYCOPROTEIN OF 2 STRAINS OF LACTATE DEHYDROGENASE-ELEVATING VIRUS THAT DIFFER IN NEUROPATHOGENICITY

ORF 5 encoding the primary envelope glycoprotein, VP-3P, of a highly n europathogenic isolate of lactate dehydrogenase-elevating virus (LDV-v ) has been sequenced. It exhibits 92% nucleotide identity with the ORF 5 of an LDV isolate that lacks neuropathogenicity, LDV-P, and the ami no acid identities of the predicted VP-3Ps of the two strains is 90%. Most striking, however, is the absence in the ectodomain of LDV-v VP-3 P of two out of three potential N-glycosylation sites present in the e ctodomain of VP-3P of LDV-P. The ectodomain of VP-3P has been implicat ed to play an important role in host receptor interaction. VP-3P of an other neuropathogenic LDV strain, LDV-C, lacks the same two N-glycosyl ation sites (Godeny et al., 1993). In vitro transcription/translation of the ORFs 5 of LDV-P and LDV-v indicated that all three N-glycosylat ion sites in the ectodomain of LDV-P VP-3P became glycosylated when sy nthesized in the presence of microsomal membranes, whereas the glycosy lation of the ORF 5 proteins of LDV-v and LDV-C was consistent with gl ycosylation at a single site. No other biological differences between the neuropathogenic and non-neuropathogenic strains have been detected . They replicate with equal efficiency in mice and in primary macropha ge cultures.