Inactivation of formyltransferase (wbkC) gene generates a Brucella abortus rough strain that is attenuated in macrophages and in mice

Rough mutants of Brucella abortus were generated by disruption of wbkC gene which encodes the formyltransferase enzyme involved in LPS biosynthesis. In bone marrow-derived macrophages the B. abortusDeltawbkC mutants were attenuated, could not reach a replicative niche and induced higher levels of IL-12 and TNF-alpha when compared to parental smooth strains. Additionally, mutants exhibited attenuation in vivo in C57BL/6 and interferon regulatory factor-1 knockout mice. DeltawbkC mutant strains induced lower protective immunity in C56BL/6 than smooth vaccine S19 but similar to rough vaccine RB51. Finally, we demonstrated that Brucella wbkC is critical for LPS biosynthesis and full bacterial virulence.

Characterization of field bovine herpesvirus samples using random amplified polymorphic DNA (RAPD)

Bovine herpesvirus 5 (BoHV-5) and Bovine herpesvirus 1 (BoHV-1) are members of the family Herpesviridae, subfamily Alphaherpesvirinae. Although BoHV-1 and BoHV-5 are closely related viruses (their genomes share 85% similarity), they exhibit some important differences at the genetic level which may explain the differences in their pathogenicity and epidemiological characteristics. Bovine herpesvirus 5 is a neurovirulent virus that causes fatal meningoencephalitis in calves and has been described in Australia, Argentina, United States and Brazil. BoHV-1 causes infectious bovine rhinotracheitis (IBR) and is reported around the world. The aim of this study was to establish the use of random amplified polymorphic DNA (RAPD) followed by phylogenetic analysis to characterize field samples of bovine herpesviruses. This technique was used to study the relationship of Brazilian samples of bovine encephalitis virus isolated in semen and the central nervous system (CNS), including BoHV-1.1 and BoHV-1.2 reference subtype virus for comparison. The samples tested could be clearly separated into BoHV-1.1, BoHV-1.2 and BoHV-5 by RAPD using two different primers. The results showed that RAPD analysis can be used as a diagnostic as well as a molecular epidemiological tool for herpesviruses.