A glycoprotein E deletion mutant of bovine herpesvirus 1 infects the same limited number of tissues in calves as wild-type virus, but for a shorter period

To gain insight into the role of glycoprotein E of bovine herpesvirus 1 (BHV-1), we compared the distribution of wild-type (wt) BHV-1 with that of a gE deletion mutant (gE-) in calves after intranasal inoculation. The wt-infected calves had severe clinical signs, but the gE--infected calves were virtually free of clinical signs. At 3, 4, 7, 8, 44, 45, 50 and 51 days post-infection (p.i.), one calf from each group was killed and tissues were collected for virus isolation and PCR analysis. At 3, 4, 7 and 8 days p.i., infectious virus could be isolated only from the nasopharyngeal mucosa, parotid gland and nearby lymphoid tissues for both the wt- and gE--infected calves. At 3 and 4 days p.i., virus titres in these tissues were comparable in both the wt- and gE--infected calves. However, the virus titres were significantly reduced at 7 and 8 days p.i. in the gE--infected calves, but not in the wt-infected calves. Semi-quantitative PCR analysis revealed that for the entire infection period (3 to 51 days p.i.) significantly more BHV-1 DNA was detected in the trigeminal ganglia (TG) of the wt-infected calves than in those of the gE--infected calves. We conclude that the gE- mutant infects the same limited number of tissues as wt BHV-1, but for a shorter period