PESQUISA VETERINÁRIA BRASILEIRA

Abstract in English:

ABSTRACT.- Holz C.L., Cibulski S.P., Teixeira T.F., Batista H.B.C.R., Dezen D., Campos F.S., Varela A.P.M. & Roehe P.M. 2010. Serum neutralization with different types and subtypes of bovine herpesvirus 1 and 5. Pesquisa Veterinária Brasileira 30(7):515-522. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro Saúde Animal, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@gmail.com The serum neutralization (SN) test is the gold standard method to measure neutralizing antibodies to bovine herpesviruses. However, in view of the further subdivisions of bovine herpesviruses in types/subtypes, defining which virus to use at challenge in SN tests may be difficult. In view of that, this study was carried out to re-evaluate (SN) sensitivity with different types/subtypes of bovine herpesviruses types 1 (BoHV-1) and 5 (BoHV-5) as challenge viruses. Bovine sera (n=810) were collected from two distinct geographic regions and tested by SN with three type 1 viruses (BoHV-1.1 strains “Los Angeles” and “EVI123/98”; BoHV-1.2a strain “SV265/96”) and three type 5 viruses (BoHV-5a strain “EVI88/95”; BoHV-5b strain “A663” and BoHV-5c “ISO97/95”). SN tests were performed with a 1 hour incubation of the serum-virus mixtures at 37ºC against 100 TCID50 of each of the viruses. SN sensitivity varied greatly depending on the challenge virus used in the test. The highest sensitivity (327 positive/810 total sera tested; 40.37%) was attained when the positive results to the six viruses were added together. No association could be found between any particular type or subtype of virus and the sensitivity of the test. When positive results to each single strain were considered, SN sensitivity varied from 41.7% to 81.7%, depending on the virus and the geographic region of origin of the sera. Variation was detected even when challenge viruses belonged to the same subtype, where disagreement between positive results reached 41%. These results indicate that one hour incubation SN tests against single viruses, as performed here, may display a significantly low sensitivity (p=0.05); performing SN tests against a number of different viruses may increase considerably SN sensitivity. Furthermore, the choice of virus used for challenge is critical in SN tests. In addition, sera from different geographic regions may give rise to disagreeing results with different strains of BoHV-1 and BoHV-5. This might be particularly relevant for control programs and in international trade, were maximum sensitivity should be targeted.

• BoHV-1 BoHV-5 bovine herpesvirus 1 and 5 herpesvírus bovinos 1e 5

Abstract in Portuguese:

RESUMO.- Holz C.L., Cibulski S.P., Teixeira T.F., Batista H.B.C.R., Dezen D., Campos F.S., Varela A.P.M. & Roehe P.M. 2010. Serum neutralization with different types and subtypes of bovine herpesvirus 1 and 5. [Soroneutralização com diferentes tipos e subtipos de herpesvírus bovinos 1e 5.] Pesquisa Veterinária Brasileira 30(7):515-522. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro Saúde Animal, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@gmail.com O teste de soroneutralização (SN) é o método padrão para a mensuração de anticorpos neutralizantes para herpesvírus bovinos. Entretanto, com as subdivisões propostas destes agentes em tipos e subtipos, a definição de qual amostra utilizar como virus de desafio à SN pode ser difícil. Em vista disso, este estudo foi realizado para re-avaliar a sensibilidade de testes de SN utilizando diferentes tipos e subtipos de herpesvírus bovinos tipos 1 (BoHV-1) e 5 (BoHV-5) como amostras de desafio. Soros bovinos (n=810) foram coletados de duas regiões geográficas distintas e testados frente a amostras do tipo 1 (BoHV-1.1: amostras “Los Angeles” e “EVI123/98”, BoHV-1.2a: amostra “SV265/96”) e três amostras do tipo 5 (BoHV-5a: “EVI88/95”; BoHV-5b: “A663” e BoHV-5c “ISO97/95”). Os testes de SN foram realizados com incubação de 1 hora a 37ºC da mistura soro-vírus, frente a 100 doses infectantes para 50% dos cultivos celulares (DICC50) de cada um dos vírus. A sensibilidade da SN variou grandemente em função do vírus utilizado no teste. A maior sensibilidade (327 soros positivos/810 soros testados; 40.37%) foi alcançada quando os resultados positivos frente aos seis diferentes vírus foram somados. Nenhuma associação foi detectada entre determinado tipo/subtipo de vírus e a sensibilidade do teste. Quando resultados positivos frente a cada vírus foram considerados isoladamente, a sensibilidade da SN variou entre 41,7% a 81,7%, dependendo do vírus de desafio e da região geográfica de origem das amostras de soro. Variação foi detectada mesmo quando as amostras de desafio pertenciam a um mesmo subtipo; a discrepância entre os resultados positivos atingiu até 41%. Estes resultados indicam que testes de SN contra amostras isoladas de vírus podem apresentar uma sensibilidade notadamente baixa; o emprego de diferentes amostras de vírus de desafio pode aumentar consideravelmente a sensibilidade da prova. Além disso, a escolha da amostra de vírus para a realização do teste é crítica. Outro achado importante é que sorors de diferentes regiões geográficas podem dar resultados discordantes frente a diferentes amostras de BoHV-1 e BoHV-5. Estes achados são particularmente relevantes para programas de controle destas infecções e para o comércio internacional, onde a sensibilidade deve ser maximizada.

Abstract in English:

ABSTRACT.- Holz C.L., Cibulski S.P., Teixeira T.F., Batista H.B.C.R., Campos F.S., Silva J.R., Varela A.P.M., Cenci A., Franco A.C. & Roehe P.M. 2009. [Seroprevalence of bovine herpesvirus types 1 and/or 5 in the state of Rio Grande do Sul.] Soroprevalência de herpesvírus bovinos tipos 1 e/ou 5 no Estado do Rio Grande do Sul. Pesquisa Veterinária Brasileira 29(9):767-773. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro Saúde Animal, Estrada do Conde 6000, Cx. Postal 47, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@gmail.com This study was carried out to estimate the prevalence of antibodies to bovine herpesviruses types 1(BoHV-1) and 5 (BoHV-5) in the state of Rio Grande do Sul (RS), Brazil, by testing serum samples against different BoHV-1 and BoHV-5 strains. The sera examined were obtained from a larger sample designed to estimate the prevalence of bovine brucellosis within the state. All sera were collected from cows 24 months or older, not vaccinated to bovine herpesviruses, from both dairy and beef herds. The number of samples to be tested was calculated based on an estimated prevalence of infection of 33%, with an average standard deviation of £1% and a 95% limit of agreement. Sera from 2.200 cattle from 390 farms distributed in 158 counties were tested by serum neutralization (SN) tests in search for antibodies to the following strains: BoHV-1.1 (strains EVI123/98 and Los Angeles), BoHV-5a (strain EVI88/95) and BoHV-5b (strain A663). The overall seroprevalence to BoHV-1 and BoHV-5 in the sampled herds was 29.2% (642/2.200); seropositive animals were detected in 225 (57.7%) of the sampled farms. Prevalence estimates varied according to the virus used for challenge in SN tests. The highest prevalence and sensitivity were attained when positive SN results against the four different strains were added together. The use of only one virus for challenge in SN tests would lead to a loss in sensitivity from 20.4% to 34.6% when compared to the combined SN-positive results. These findings provide evidence that antibodies to BoHV-1 and BoHV-5 are largely spread in dairy and beef herds in RS, although prevalence in distinct geographic regions is quite variable. The results were strongly affected by the virus strains used for challenge in SN testing. This must be taken into account when performing serologic tests to detect BoHV-1 and BoHV-5 antibodies. As SN test is not capable of discriminating between antibody responses to BoHV-1 and BoHV-5, type-specific prevalence remains unknown.

• Bovine herpesvirus type 1 bovine herpesvirus type 5 BoHV-1 BoHV-5 herpesvírus bovinos tipo 1 herpesvírus bovinos tipo 5

Abstract in Portuguese:

RESUMO.- Holz C.L., Cibulski S.P., Teixeira T.F., Batista H.B.C.R., Campos F.S., Silva J.R., Varela A.P.M., Cenci A., Franco A.C. & Roehe P.M. 2009. [Seroprevalence of bovine herpesvirus types 1 and/or 5 in the state of Rio Grande do Sul.] Soroprevalência de herpesvírus bovinos tipos 1 e/ou 5 no Estado do Rio Grande do Sul. Pesquisa Veterinária Brasileira 29(9):767-773. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro Saúde Animal, Estrada do Conde 6000, Cx. Postal 47, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@gmail.com Este estudo objetivou estimar a prevalência de anticorpos contra os herpesvírus bovinos tipos 1 e 5 (BoHV-1 e BoHV-5) no Estado do Rio Grande do Sul (RS), Brasil, frente a diferentes cepas de BoHV-1 e BoHV-5. As amostras de soro utilizadas foram extraídas de uma amostragem mais ampla, desenhada para estimar a prevalência de brucelose bovina no Estado. Todos os soros foram coletados de vacas com idade igual ou superior a 24 meses de idade, não vacinadas contra herpesvírus bovinos, de rebanhos de corte e leite. O cálculo amostral foi baseado em uma expectativa de prevalência média de infecção de 33%, considerando-se um erro padrão não superior a 1% e um intervalo de confiança de 95%. Com base nesse cálculo foram examinados 2.200 soros, provenientes de 390 propriedades e 158 municípios. Os soros foram analisados na busca de anticorpos contra BoHV-1 e BoHV-5 pela técnica de soroneutralização (SN), executada frente a quatro cepas de vírus distintas: EVI123/98 e Los Angeles (BoHV-1.1); EVI88/95 (BoHV-5a) e A663 (BoHV-5b). A prevalência média de anticorpos contra o BoHV-1 e BoHV-5 nos animais amostrados foi de 29,2% (642/2200); animais soropositivos foram identificados em 57,7% (225/390) dos rebanhos. As estimativas de prevalência variaram de acordo com a cepa e/ou vírus utilizado para o desafio nos testes de SN. A prevalência e a sensibilidade mais altas foram obtidas quando os resultados positivos à SN frente aos quatro vírus distintos foram somados. O uso de somente um vírus de desafio na SN levaria a redução de sensibilidade de 20,4% a 34,6% quando comparada com os resultados positivos combinados. Estes achados evidenciam que anticorpos contra BoHV-1 e BoHV-5 estão amplamente difundidos nos rebanhos do RS, embora a prevalência em distintas regiões geográficas seja bastante variada. Os resultados obtidos nas estimativas de prevalência foram fortemente afetados pelas diferentes amostras de vírus usadas nos testes de SN. Esse fato deve ser levado em consideração quando estudos sorológicos para BoHV-1 e BoHV-5 forem realizados. Como a SN não é capaz de discriminar as respostas de anticorpos para BoHV-1 e BoHV-5, a prevalência tipo-específica permanece desconhecida.

Abstract in English:

ABSTRACT.- Teixeira T.F., Holz C.L., Caixeta S.P.M.B., Dezen D., Cibulski S.P., Silva J.R., Rosa J.C.A., Schmidt E., Ferreira J.C., Batista H.B.C.R., Caldas E., Franco A.C. & Roehe P.M. 2008. [Rabies diagnosis in the state of Rio Grande do Sul, Brazil, from 1985 to 2007.] Diagnóstico de raiva no Rio Grande do Sul, Brasil, de 1985 a 2007. Pesquisa Veterinária Brasileira 28(10):515-520. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro-Saúde Animal, Cx. Postal 2076, Porto Alegre, RS 90001-970, Brazil. E-mail: proehe@ufrgs.br The results of 23 years of rabies diagnosis carried out at the Veterinary Research Institute Desidério Finamor, in the state of Rio Grande do Sul, RS, Brazil, are reported. From 1985 to 2007, a total of 23.460 specimens were examined, corresponding to 95% of the total number of samples submitted to rabies laboratory diagnosis notified within the state. Diagnostic methods included standard techniques such as the fluorescent antibody test (FAT) and mouse inoculation test (MIT). No cases of human rabies occurred in the period. Rabies virus (RV) was detected in 739 specimens (3.1%), from which 656 (88.7%) were from cattle. The virus was also identified in specimens from 23 dogs (3.1%), 21 horses (2.9%), 29 bats (4.0%), 4 cats (0.5%), 3 sheep (0.4%), 2 pigs (0.27%) and a wild animal of undetermined species (0.13%). The last case of rabies associated with a canine variant was diagnosed in 1988. Two cases of rabies associated with bat variant viruses were reported, in a domestic cat (2001) and in a dog (2007). In cattle, a marked tendency to a decrease in the number of cases was detected in the examined period. In contrast, an increase in the number of cases in haematophagous as well as in non haematophagous bats is noticed. However, as the number of bat specimens submitted for diagnosis has increased, this finding most likely reflects a higher degree of awareness on the possible role for bats in the rabies transmission cycle, rather than any particular changes on the virus or its hosts.

• Rabies epidemiology diagnosis incidence

Abstract in Portuguese:

ABSTRACT.- Teixeira T.F., Holz C.L., Caixeta S.P.M.B., Dezen D., Cibulski S.P., Silva J.R., Rosa J.C.A., Schmidt E., Ferreira J.C., Batista H.B.C.R., Caldas E., Franco A.C. & Roehe P.M. 2008. [Rabies diagnosis in the state of Rio Grande do Sul, Brazil, from 1985 to 2007.] Diagnóstico de raiva no Rio Grande do Sul, Brasil, de 1985 a 2007. Pesquisa Veterinária Brasileira 28(10):515-520. Instituto de Pesquisas Veterinárias Desidério Finamor, Fepagro-Saúde Animal, Cx. Postal 2076, Porto Alegre, RS 90001-970, Brazil. E-mail: proehe@ufrgs.br The results of 23 years of rabies diagnosis carried out at the Veterinary Research Institute Desidério Finamor, in the state of Rio Grande do Sul, RS, Brazil, are reported. From 1985 to 2007, a total of 23.460 specimens were examined, corresponding to 95% of the total number of samples submitted to rabies laboratory diagnosis notified within the state. Diagnostic methods included standard techniques such as the fluorescent antibody test (FAT) and mouse inoculation test (MIT). No cases of human rabies occurred in the period. Rabies virus (RV) was detected in 739 specimens (3.1%), from which 656 (88.7%) were from cattle. The virus was also identified in specimens from 23 dogs (3.1%), 21 horses (2.9%), 29 bats (4.0%), 4 cats (0.5%), 3 sheep (0.4%), 2 pigs (0.27%) and a wild animal of undetermined species (0.13%). The last case of rabies associated with a canine variant was diagnosed in 1988. Two cases of rabies associated with bat variant viruses were reported, in a domestic cat (2001) and in a dog (2007). In cattle, a marked tendency to a decrease in the number of cases was detected in the examined period. In contrast, an increase in the number of cases in haematophagous as well as in non haematophagous bats is noticed. However, as the number of bat specimens submitted for diagnosis has increased, this finding most likely reflects a higher degree of awareness on the possible role for bats in the rabies transmission cycle, rather than any particular changes on the virus or its hosts.

Abstract in English:

ABSTRACT.- Spilki F.R., Esteves P.A., Franco A.C., Lima M., Holz C.L., Batista H.B.C.R., Driemeier D., Flores E.F., Weiblen R. & Roehe P.M. 2002. [Neurovirulence and neuroinvasiveness of bovine herpesvirus type 1 and 5 in rabbits.] Neurovirulência e neuroinvasividade de Herpesvírus bovinos tipos 1 e 5 em coelhos. Pesquisa Veterinária Brasileira 22(2):58-63. Centro de Pesquisas Veterinárias Desidério Finamor, Estrada do Conde 6000, Cx. Postal 47, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@orion.ufrgs.br In order to determine the capacity of bovine herpesvirus type 1 and 5 (BHV-1 and BHV-5) to invade, multiply and spread along the central nervous system (CNS) (neuroinvasiveness), as well as their potential to induce neurological illness (neurovirulence), 30 to 35 days old rabbits were inoculated with the BHV-5 strain EVI 88 / 95 and Los Angeles and Cooper BHV-1 strains, by the intrathecal (IT) and intranasal (IN) routes. The BHV-5 strain induced severe neurological clinical signs in 100% (12/12) of the rabbits inoculated by both routes. Histopathological examination revealed multifocal non-suppurative meningoencephalitis, characterized by multifocal gliosis and perivascular cuffing. Virus was recovered from many parts of the brain. Both BHV-1 strains, when inoculated via 1T route, were not neurovirulent. The strain Los Angeles, after IN inoculation, induced signs of severe respiratory disease (7/7), as well as signs of neurological impairment, indistinguishable from those induced by BHV-5, in 57% (4/7) of the infected rabbits. However, the rabbits with nervous signs revealed at histopathology vasculitis and thrombosis in lungs and brain, the latter with foci of neuronal necrosis, but no lesions indicative of encephalitis, suggesting that neural damage was probably consequent to tissue anoxia. The BHV-1 strain Cooper, after IN inoculation, induced only mild signs of respiratory disease. These findings indicate that the BHV-5 strain was both neuroinvasive and neurovirulent, since it was capable of invading, spreading and multiplying in the rabbits brains by both routes of inoculation, yet causing neurological disease, apparently consequent to vírus induced neural damage. The BHV-1 Los Angeles strain was not neuroinvasive, whereas its neurovirulence was probably consequent to tissue anoxia, which histologically seemed not to be related to direct viral pathogenic effect. The BHV-1 strain Cooper was neither neurovirulent nor neuroinvasive for rabbits. It is possible that these observations bear relationship with the frequent association of BHV-5 with encephalitis in cattle, as opposed to BHV-1 encephalitis, which is a rare event in nature.

• Infectious bovine rhinotracheitis IBR BHV-1 bovine encephalitis herpesvirus BHV-5 Rinotraqueíte infecciosa bovina herpesvírus da encefalite bovina.

Abstract in Portuguese:

RESUMO.- Spilki F.R., Esteves P.A., Franco A.C., Lima M., Holz C.L., Batista H.B.C.R., Driemeier D., Flores E.F., Weiblen R. & Roehe P.M. 2002. [Neurovirulence and neuroinvasiveness of bovine herpesvirus type 1 and 5 in rabbits.] Neurovirulência e neuroinvasividade de Herpesvírus bovinos tipos 1 e 5 em coelhos. Pesquisa Veterinária Brasileira 22(2):58-63. Centro de Pesquisas Veterinárias Desidério Finamor, Estrada do Conde 6000, Cx. Postal 47, Eldorado do Sul, RS 92990-000, Brazil. E-mail: proehe@orion.ufrgs.br Com o objetivo de avaliar a capacidade dos herpesvírus bovinos tipos 1 e 5 (BHV-1 e BHV-5) de invadir e replicar no sistema nervoso central (SNC) (neuroinvasividade), bem como sua capacidade de induzir doença neurológica (neurovirulência), coelhos com 30 a 35 dias de idade foram inoculados com uma amostra do Herpesvírus da Encefalite Bovina (BHV-5; amostra EVI 88/95) ou com amostras de BHV-1 (Los Angeles ou Cooper), pelas vias intratecal (IT) e intranasal (IN). A inoculação da amostra de BHV-5, tanto pela via 1T como IN, induziu sinais clínicos neurológicos em 100% (12/12) dos coelhos inoculados. Os exames histopatológicos revelaram um quadro de meningoencefalite não-purulenta multifocal, caracterizada por gliose multifocal e infiltrados perivasculares. O vírus foi isolado de várias áreas do SNC desses animais. As amostras de BHV-1, quando inoculadas pela via IT, não foram neurovirulentas. A amostra Los Angeles de BHV-1, quando administrada pela via IN, induziu sinais respiratórios severos, além de sinais neurológicos em 57% (4/7) dos animais inoculados. Entretanto, o exame histopatológico destes quatro animais revelou vasculite e trombose no pulmão e cérebro, este último apresentando focos de necrose neuronal, porém sem lesões indicativas de encefalite. Isso sugere que os sinais neurológicos foram, provavelmente, consequentes a prejuízos no fluxo sangüíneo encefálico, e não a danos neuronais provocados pela inoculação desse vírus. A amostra Cooper de BHV-1, quando inoculada pela via IN, induziu apenas sinais leves de infecção respiratória. Estes resultados indicam que apenas a amostra de BHV-5 foi capaz de invadir e replicar no encéfalo dos coelhos quando inoculada tanto por via IN como IT, apresentando neuroinvasividade e neurovirulência. É possível que estas observações tenham relação com o fato de amostras de BHV-5 freqüentemente causarem encefalites, em contraposição a infecções pelo BHV-1, onde encefalites são raramente observadas.