Experimental infection of rabbits with a recombinant bovine herpesvirus type 5 (BoHV-5) gI, gE and US9-negative / Infecção experimental de coelhos com um recombinante do herpesvírus bovino tipo 5 defectivo na gI, gE e US9

Bovine herpesvirus type 5 (BoHV-5) is a major cause of viral meningoencephalitis in cattle. The expression of different viral proteins has been associated with BoHV-5 neuropathogenesis. Among these, gI, gE and US9 have been considered essential for the production of neurological disease in infected animals. To evaluate the role of gI, gE and US9 in neurovirulence, a recombinant from which the respective genes were deleted (BoHV-5 gI-/gE-/US9-) was constructed and inoculated in rabbits of two age groups (four and eight weeks-old). When the recombinant virus was inoculated through the paranasal sinuses of four weeks-old rabbits, neurological disease was observed and death was the outcome in 4 out of 13 (30.7 percent) animals, whereas clinical signs and death were observed in 11/13 (84.6 percent) of rabbits infected with the parental virus. In eight weeks-old rabbits, the BoHV-5 gI-/gE-/US9- did not induce clinically apparent disease and could not be reactivated after dexamethasone administration, whereas wild type BoHV-5 caused disease in 55.5 percent of the animals and was reactivated. These findings reveal that the simultaneous deletion of gI, gE and US9 genes did reduce but did not completely abolish the neurovirulence of BoHV-5 in rabbits, indicating that other viral genes may also play a role in the induction of neurological disease.

O herpesvírus bovino tipo 5 é uma das principais causas de meningoencefalite viral em bovinos. A expressão de diferentes proteínas virais tem sido associada à neuropatogenia do BoHV-5. Entre estas, a gI, gE e US9 têm sido consideradas essenciais para a indução de sinais neurológicos nos animais infectados. Para avaliar o papel das proteínas gI, gE e US9 na neurovirulência, construiu-se um recombinante no qual os genes que codificam estas proteínas foram deletados, denominado BoHV-5 gI-/gE-/US9-. Este vírus foi inoculado em coelhos de idades diferentes (quatro e oito semanas de idade). Quando o vírus recombinante foi inoculado nos seios paranasais de coelhos de quatro semanas de idade, doença neurológica e morte foram observadas em 4 dos 13 (30,7 por cento) animais, enquanto que sinais clínicos e morte foram observados em 11/13 (84,6 por cento) dos coelhos infectados com o vírus parental. Em coelhos de oito semanas de idade, o BoHV-5 gI-/gE-/US9- não induziu sinais clínicos aparentes e, após tentativa de reativação viral por tratamento com dexametasona, o vírus não foi re-excretado. Por outro lado, o vírus selvagem causou doença clínica em 55,5 por cento dos coelhos e foi re-excretado após tratamento com dexametasona. Estes achados revelam que a deleção simultânea dos genes gI, gE e US9 reduziu mas não aboliu completamente a neurovirulência do BoHV-5 em coelhos, indicando que outros genes virais possam ter papel na indução da doença neurológica.

Molecular chaperones in the Paracoccidioides brasiliensis transcriptome

Paracoccidioides brasiliensis is a thermally dimorphic and a human pathogenic fungus. Our group has partially sequenced its transcriptome and generated a database of mycelial and yeast PbAESTs (P. brasiliensis assembled expressed sequence tags). In the present review we describe the identification of PbAESTs encoding molecular chaperones. These proteins, involved in protein folding and renaturation, are also implicated in several other biological processes, where the dimorphic transition is of particular interest. Another important issue concerning these proteins refers to their participation in the immunopathogenicity of infectious diseases. We have found 438 ESTs (184 in mycelium and 253 in yeast) encoding P. brasiliensis molecular chaperones and their co-chaperones, which were clustered in 48 genes. These genes were classified in families, corresponding to three small chaperones, nine HSP40s, 10 HSP60s, seven HSP70s, five HSP90s, four HSP100s, and 10 other chaperones. These results greatly increase the knowledge on P. brasiliensis molecular chaperones, since only eight of such proteins had been previously characterized.