Resumo

Bovine herpesvirus types 1 (BoHV-1) and 5 (BoHV-5) belong to Alphaherpesvirinae, the neurotrophic subfamily of herpesviruses, which has common genome arrangements with those of HSV-1 (herpes simplex virus type 1) BoHV-1 and 5 are important pathogens of cattle, associated mainly to respiratory and genital disease as well as a range of reproductive problems in these animals. Lithium is a monovalent cation and belongs to the group IA elements in the periodic table with complex physiological and pharmacological effects. Lithium is known to affect the behavior and replication of bacteria and viruses. The effect of lithium salts on the replication of herpes simplex virus, pseudorabies virus and vaccinia virus has been documented. The aim this study was to verify the influence of lithium choride (LiCl) on replication of BoHV-1 and BoHV-5. The MTT and Trypan blue cell viability assays was performed for determination of toxicity of the LiCl in CRIB cells. LiCl caused a concentration-dependent decrease in cell viability in CRIB cells. The maximum non-toxic concentrations of LiCl on CRIB cell viability and proliferation were determined as above and the maximum non-toxic concentrations of LiCl was 50 mM. CRIB cells were inoculated with BoHV-1 or BoHV-5 at multiplicity of infection 0.1 and, after adsorption, treated with 50, 25, 10 or 5 mM of LiCl during three days. Four different concentrations of LiCl were evaluated (50, 25, 10 and 5 mM) on replication of the BoHV-1 and 5. Titrations were performed by the method of Reed & Müench to determine the effect of LiCl on the replication of BoHV-1 and 5. Statistical significance was evaluated using t-Student test in SPSS 18.0. LiCl caused a dose-dependent decrease in viral titers of both viruses. The dose of 50, 25, 10 and 5 mm, inhibited, respectively, 4.16 (p<0,05), 1.54 (p<0,05), 0.71 (p<0,05), and 0.17 log (p>0,05) of the viral titer of the BoHV-1 and 3.76 (p<0,05), 1.26 (p<0,05), 0.38 and 0.22 (p>0,05) log (p=0,05) the titer of the BoHV-5. No virucidal effect was observed (data not shown). Inhibition of BoHV-1 replication apparently was greater than that observed for BoHV-5. The results showed that the BoHV-1 and BoHV- 5 infectivity were decreased in a dose-dependent manner after the treatment of LiCl.