PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

ABSTRACT.- Dezengrini R., Silva S.C., Weiss M., Kreutz L.C., Weiblen R. & Flores E.F. 2010. [Activity of three antiviral drugs against bovine herpesviruses 1, 2 and 5 in cell culture.] Atividade de três drogas antivirais sobre os herpesvírus bovino tipos 1, 2 e 5 em cultivo celular. Pesquisa Veterinária Brasileira 30(10):855-860. Setor de Virologia, Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: eduardofurtadoflores@gmail.com The activity of three anti-herpetic drugs (Acyclovir [ACV], Gancyclovir [GCV] and Foscarnet [PFA]) was tested against bovine herpesvirus 1 (BoHV-1), 2 (BoHV-2) and 5 (BoHV-5) in vitro using the plaque reduction assay. Different drug concentrations were tested against one hundred 50% tissue culture infectious dose (TCID50) of the respective viruses. Drug concentrations lower than 200µg/mL resulted in viability rates of more than 80% for MDBK and Hep2 cells in the MTT test (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). The selectivity index (IS) of the drugs was calculated dividing the concentration of the drug that is cytotoxic for 50% of the cells (CC50) by the concentration of the drug that was effective in reducing by 50% the number of viral plaques (EC50) for the three herpesviruses. Thus, ACV was shown to be moderately active against BoHV-1 (EC50: 112.9mg/mL; IS: 4.5), BoHV-2 (EC50: 114.2mg/mL; IS: 4.5) and BoHV-5 (EC50: 96.9mg/mL; IS: 5.3). GCV was effective against BoHV-2 (EC50: 33.5mg/mL; IS: 16.6), moderately effective against BoHV-5 (EC50: 123.2mg/mL; IS: 4.5) and poorly active against BoHV-1 (EC50: 335.8mg/mL; IS: 1.7). PFA exhibited the highest antiviral activity, being the only drug that, at concentration of 100mg/mL, completely inhibited plaque formation by all three viruses. PFA was the most effective in vitro against BoHV-1 (EC50: 29.5mg/mL; IS: 42.2), BoHV-2 (EC50: 45.2mg/mL; IS: 27.6) and BoHV-5 (EC50: 7.8mg/mL; IS: 160.6). Thus, the results indicate that PFA is a promising candidate for experimental therapeutic testing in vivo against bovine herpesviruses.

• Antivirals BoHV-1 BoHV-2 BoHV-5 Foscarnet Gancyclovir Acyclovir antivirais Ganciclovir Aciclovir

Abstract in Portuguese:

RESUMO.- Dezengrini R., Silva S.C., Weiss M., Kreutz L.C., Weiblen R. & Flores E.F. 2010. [Activity of three antiviral drugs against bovine herpesviruses 1, 2 and 5 in cell culture.] Atividade de três drogas antivirais sobre os herpesvírus bovino tipos 1, 2 e 5 em cultivo celular. Pesquisa Veterinária Brasileira 30(10):855-860. Setor de Virologia, Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: eduardofurtadoflores@gmail.com A atividade de três fármacos antivirais (Aciclovir [ACV], Ganciclovir [GCV] e Foscarnet [PFA]) foi testada in vitro frente aos herpesvírus bovino tipos 1 (BoHV-1), 2 (BoHV-2) e 5 (BoHV-5). Para isso, utilizou-se o teste de redução de placas virais em cultivo celular, testando-se diferentes concentrações dos fármacos frente a 100 doses infectantes para 50% dos cultivos celulares (DICC50) dos respectivos vírus. Pelo teste de MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), verificou-se que concentrações inferiores a 200µg/mL dos três antivirais resultaram em índices de viabilidade de células MDBK e Hep2 superiores a 80%. Com base na concentração citotóxica para 50% das células (CC50) e na concentração dos fármacos efetiva para inibir em 50% o número de placas virais (EC50), calculou-se o índice de seletividade (IS) dos antivirais para os três herpesvírus. Assim, o ACV demonstrou ser moderadamente ativo frente ao BoHV-1 (EC50: 112,9mg/mL e IS: 4,5), ao BoHV-2 (EC50: 114,2 mg/mL e IS: 4,5) e BoHV-5 (EC50: 96,9mg/mL e IS: 5,3). O GCV apresentou atividade moderada frente ao BoHV-2 (EC50: 33,5mg/mL e IS: 16,6) e, em menor grau, contra o BoHV-5 (EC50: 123,2mg/mL e IS: 4,5), sendo ineficaz frente ao BoHV-1 (EC50: 335,8mg/mL e IS: 1,7). O PFA apresentou atividade antiviral mais pronunciada, sendo o único fármaco que, na concentração de 100µg/mL, inibiu completamente a produção de placas pelos três vírus testados. O PFA foi o mais efetivo in vitro frente ao BoHV-1 (EC50: 29,5mg/mL e IS: 42,2), ao BoHV-2 (EC50: 45,2mg/mL e IS: 27,6) e ao BoHV-5 (EC50: 7,8mg/mL e IS: 160,6). Portanto, os resultados obtidos indicam que o PFA pode se constituir em um candidato para terapia experimental de infecções pelos herpesvírus de bovinos in vivo.

Abstract in English:

ABSTRACT.- Dezengrini R., Silva S.C., Weiss M., Oliveira M.S., Traesel C.K., Weiblen R. & Flores E.F. 2010. [Effects of Foscarnet on the infection by bovine herpesviruses 1 and 5 in rabbits.] Efeitos do Foscarnet sobre a infecção pelos herpesvírus bovino tipos 1 e 5 em coelhos. Pesquisa Veterinária Brasileira 30(8):623-630. Setor de Virologia, Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av, Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: eduardofurtadoflores@gmail.com The activity of Foscarnet (PFA) against three bovine herpesviruses (BoHVs) was previously demonstrated in cell culture. Herein we evaluated the effects of PFA on the infection and disease by BoHV-1 and BoHV-5 in a rabbit model. Rabbits inoculated with BoHV-5 in the conjunctival sac (IC) and treated with PFA (100 mg/kg/day) from day 1 to 17 post-inoculation (pi) shed less virus between days 2 and 6 pi comparing to untreated controls; this difference was significant at day 3 pi [F(9,108) = 2,23; P<0.03]. The morbidity and mortality rates of rabbits inoculated with BoHV-5 IC or intranasally (IN) were also significantly reduced in PFA-treated rabbits (50%; 11/22) comparing to untreated controls (95.4%; 21/22) (P<0.0008). In rabbits inoculated IC with BoHV-1, a reduction in virus shedding was observed in PFA-treated animals between days 1 and 4 pi; 6 and 7 pi. In addition, PFA-treated rabbits presented a longer incubation period and a shorter clinical course comparing to untreated controls (P<0.005 and P<0.04, respectively). The frequency and severity of ocular signs were also reduced in the PFA-treated group. These results demonstrate that PFA is effective against BoHV-1 and BoHV-5 in vivo and open the way towards its use in experimental therapy of herpetic infections in domestic animals.

• Antivirals BoHV-1 BoHV-5 PFA bovine herpesviruses 1 bovine herpesviruses 5 Foscarnet herpesvírus bovino tipo 1 herpesvírus bovino tipo 5

Abstract in Portuguese:

RESUMO.- Dezengrini R., Silva S.C., Weiss M., Oliveira M.S., Traesel C.K., Weiblen R. & Flores E.F. 2010. [Effects of Foscarnet on the infection by bovine herpesviruses 1 and 5 in rabbits.] Efeitos do Foscarnet sobre a infecção pelos herpesvírus bovino tipos 1 e 5 em coelhos. Pesquisa Veterinária Brasileira 30(8):623-630. Setor de Virologia, Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av, Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: eduardofurtadoflores@gmail.com