Efficacy of leptospiral commercial vaccines on the protection against an autochtonous strain recovered in Brazil

Abstract In swine and bovines, leptospirosis prevention and control is carried out via vaccination of susceptible animals using bacterins. However, the efficiency of leptospirosis vaccines has been questioned. This work aimed to investigate the potency of five leptospirosis vaccines sold commercially in Brazil, challenging the animals with one autochthonous strain of Leptospira, Canicola serovar, denoted LO4, isolated from swine. The standard protocol was followed, and renal carriers of Leptospira were identified among the surviving animals by culture and PCR. Of the five vaccines tested, only two proved effective. None of the surviving animals was positive by culture; however, one animal was positive by PCR. Three of the five vaccines sold commercially in Brazil for the immunization of swine or bovines failed the test of the efficacy to protect the vaccinated animals following challenge with an autochthonous Leptospira strain, Canicola serovar. The two vaccines provided protection against the renal carrier state in the surviving animals. The criteria used to produce leptospirosis bacterins sold commercially in Brazil must be reviewed. The industry should support researches on leptospiral vaccinology to improve the quality of the present vaccines and discover new immunogenic strains, because it is known that vaccination is one of the most important tools to increase the reproduction rates in livestock.

Prevalência de leptospirose em rebanhos bovinos no Pantanal de Mato Grosso do Sul / Prevalence of leptospirosis in cattle herds in the Pantanal of Mato Grosso do Sul

Foi realizado um estudo epidemiológico da leptospirose em fêmeas acima de 24 meses, provenientes de 246 rebanhos, e 2.766 animais amostrados aleatoriamente nos nove municípios que compõem a região do Pantanal de Mato Grosso do Sul, bem como identificados os fatores de risco associados à doença. As amostras de sangue foram coletadas no período de setembro a novembro de 2009 e examinadas pelo teste de aglutinação microscópica ante uma coleção de 24 antígenos vivos de Leptospira spp., representantes dos sorovares Australis, Bratislava, Autumnalis, Butembo, Castellonis, Batavie, Canicola, Whitcombi, Cynopteri, Grippotyphosa, Hebdomadis, Copenhageni, Icterohaemorrhagiae, Javanica, Panamá, Pomona, Pyrogenes, Hardjo, Wolffi, Shermani, Tarassovi, Sentot, Andamana e Patoc. Adicionalmente, representantes de doze estirpes de leptospiras isoladas no Brasil foram adicionados à coleção de antígenos do teste de soroaglutinação microscópica (SAM). A prevalência aparente foi de 66% e a prevalência real de animais infectados, de 79,80%, com intervalo de confiança (IC) de 95% (78,3-81,3) e 241 rebanhos apresentando pelo menos um animal reagente. Os sorovares mais prováveis foram o Hardjo seguido pelo Wolffi. Os resultados demonstram que a leptospirose bovina continua presente no Pantanal, com alta prevalência tanto em rebanhos quanto em indivíduos, sendo os principais fatores de risco para a doença o tipo de exploração e a raça.(AU)

This is an epidemiological study of leptospirosis in 24 month-old females from 246 herds. Two thousand, seven hundred and sixty six (2,766) animals were randomly sampled in the nine counties comprising the region of Pantanal of Mato Grosso do Sul, Brazil. The risk factors associated with the disease were also identified. Blood samples were collected from September to November 2009 and examined by the microscopic agglutination test (MAT) against a collection of 24 live antigens of Leptospira spp., representatives of serovars Australis, Bratislava, Autumnalis, Butembo, Castellonis, Batavie, Canicola Whitcombi, Cynopteri, Grippotyphosa, Hebdomadis, Copenhageni, Icterohaemorrhagiae, Javanica, Panama, Pomona, Pyrogenes, Hardjo, Wolffi, Shermani, Tarassovi, Sentot, Andamana, and Patoc. Additionally, twelve representatives of Leptospira strains isolated in Brazil were added to the collection of antigens for the microscopic agglutination test (MAT). The apparent prevalence was 66% and the actual prevalence of infected animals was 79.80%, with a confidence interval of 95% (78.3 to 81.3) and 241 herds having at least one reactive animal. The most likely serovars were Hardjo followed by Wolffi. Results show that bovine leptospirosis is still present in Pantanal, with high prevalence both in animals and herds, the main risk factors for the disease being the type of cattle farming and breeding.(AU)

Occurrence of anti-Toxoplasma gondii, Neospora caninum and Leptospira spp. antibodies in opossums (Didelphis spp.) in São Paulo State, Brazil / Ocorrência de anticorpos anti-Toxoplasma gondii, anti-Neospora caninum e antiLeptospira spp. em gambás (Didelphis spp.) no estado de São Paulo, Brasil

Opossum (Didelphis spp.) is an omnivorous marsupial native to the Americas that shows synanthropic behavior in urban areas. Despite its proximity to domestic animals and humans, knowledge of its participation in the epidemiology of some zoonotic agents is substantial. This study aimed to determine the presence of antibodies against Toxoplasma gondii, Neospora spp. and Leptospira spp. in blood samples collected from opossums in 18 municipalities in the state of São Paulo, Brazil, between 2003 and 2008. Blood samples from 343 opossums: Didelphis aurita (n = 256) and Didelphis albiventris (n = 87) were obtained. These were tested to detect antibodies against T. gondii, using the modified agglutination test (MAT-Toto; cutoff ≥ 25); Neospora spp., using the indirect fluorescent antibody test (IFAT; cutoff ≥ 25); and Leptospira spp., using the microscopic agglutination test (MAT-Lepto; cutoff ≥ 100). Frequency of anti-T. gondii, Neospora spp. and Leptospira spp. antibodies were in 22.7%, 1.5% and 3.5%, respectively. The serogroups-serovars of Leptospira spp. presenting positive MAT-Lepto reactions were: AutumnalisButembo; Mini-Mini; Ballum-Castellonis; Icterohaemorrhagiae-Icterohaemorrhagiae; Icterohaemorrhagiae-Copenhageni and Grippotyphosa-Grippotyphosa or Bananal. This study demonstrated that these zoonotic agents are circulating in opossum populations in the state of São Paulo. Therefore, investigations regarding the role of marsupials in the epidemiology of each of these diseases should be conducted, especially to understand the behavior of these animals as zoonosis maintenance hosts.(AU)

O gambá (Didelphis spp.) é um marsupial onívoro nativo das Américas que apresenta comportamento sinantrópico em áreas urbanas. Apesar da sua proximidade com animais domésticos e o homem, o conhecimento da sua participação na epidemiologia de alguns agentes zoonóticos é fundamental. Este estudo objetivou determinar a presença de anticorpos contra Toxoplasma gondii, Neospora spp. e Leptospira spp. em amostras de sangue colhidas de gambás de 18 municípios do estado de São Paulo, Brasil, entre 2003 e 2008. Foram obtidas amostras sanguíneas de 343 gambás: Didelphis aurita (n = 256) e Didelphis albiventris (n = 87). As amostras foram testadas para detecção de anticorpos contra T. gondii, utilizando o teste de aglutinação modificado (TAM-Toxo; ponto de corte ≥ 25); Neospora spp., utilizando a reação de imunofluorescência indireta (RIFI; ponto de corte ≥ 25); e Leptospira spp., utilizando a soroaglutinação microscópica (SAM-Lepto; ponto de corte ≥ 100). As frequências de anticorpos contra T. gondii, Neospora spp. e Leptospira spp. foram 22,7%, 1,5% e 3,5%, respectivamente. Os sorogrupossorovares de Leptospira spp. que apresentaram soropositividade foram: Autumnalis-Butembo; Mini-Mini; Ballum-Castellonis; Icterohaemorrhagiae-Icterohaemorrhagiae; Icterohaemorrhagiae-Copenhageni e Grippotyphosa-Grippotyphosa ou Bananal. Esse estudo demonstrou que esses agentes estão circulando em populações de gambás no estado de São Paulo. Desta forma, investigações que visam determinar o papel dos marsupiais na epidemiologia de cada doença devem ser conduzidas, especialmente visando o entendimento do comportamento desses animais como hospedeiros dessas zoonoses.(AU)

Cross-protection between experimental anti-leptospirosis bacterins

We investigated the existence of cross-protection between two anti-leptospirosis monovalent experimental bacterins produced with two strains of Leptospira serogroup Pomona: Fromm strain of serovar Kennewicky, isolated from pigs in the United States, and strain GR6 of serovar Pomona isolated from pigs in Brazil. Both were added of aluminum hydroxide as an adjuvant. Experimental bacterins were tested with the hamster potency test in order to assess protection provided against the disease and against the establishment of kidney infection. Controls were polyvalent commercial vaccine produced with Leptospira strains isolated outside Brazil, which included a representative of Pomona serovar, or Sorensen solution added of aluminum hydroxide adjuvant. The challenge was performed with cross-strains of serogroup Pomona tested in accordance with international standards established for the potency test. After 21 days of the challenge, survivors were killed to evaluate the condition of Leptospira renal carrier. Experimental bacterins protected hamsters against homologous and heterologous strains, demonstrating the existence of cross-protection. The commercial vaccine protected the hamsters challenged with both strains, but there was a high proportion of animals diagnosed as renal carriers when the challenge was performed with strain GR6, isolated from pigs in Brazil.

Tuberculosis in goats and sheep slaughtered in the semiarid of the Paraíba state, Northeast region of Brazil / Tuberculose em caprinos e ovinos abatidos no semiárido da Paraíba, Brasil

The aim of this work was to isolate and characterize microorganisms in hypertrophied lymph nodes or gross lesions suggestive of tuberculosis collected from 12 goats and 28 sheep slaughtered at the public slaughterhouse of Patos municipality, Paraíba State, in the Northeast region of Brazil. The identification of mycobacteria was performed by the PRA method (PCR-Restriction Enzyme Analysis). Histopathological examination of lesions was also performed. Organs affected were liver, lung, mammary gland, bladder and mediastinal, mesenteric, submandibular, parotid, popliteal, precrural, prescapular and superficial inguinal lymph nodes. Histopathological examination showed the presence of granulomas in 8 (20.00%) animals. Of the 12 goats, 1 (8.33%) was positive in the culture of mycobacteria, and by PRA method the isolate was classified as belonging to the M. tuberculosis complex. Two (7.14%) sheep were positive for the presence of environmental mycobacteria. There was isolation of Corynebacterium pseudotuberculosis in 8 (66.66%) goats and 17 (60.71%) sheep, and simultaneous isolation of mycobacteria and C. pseudotuberculosis in 1 (8.33%) goat and 1 (3.57%) sheep. The isolation of mycobacteria of the M. tuberculosis complex in goats in this study raises concerns of public health, as professionals involved in handling these animals and the meat and milk consumers are exposed to the risk [...]

O objetivo do presente trabalho foi isolar e tipificar micro-organismos presentes em linfonodos hipertrofiados ou lesões macroscópicas sugestivas de tuberculose colhidos de 12 caprinos e 28 ovinos abatidos no matadouro público do município de Patos, Paraíba. A identificação de micobactérias foi feita com o método PRA (PCR-Restriction Enzyme Analysis). Também foi realizado o exame histopatológico das lesões. Os órgãos afetados foram fígado, pulmão, glândula mamária, bexiga e linfonodos mediastínicos, mesentéricos, submandibulares, parotídeos, poplíteos, pré-crural, pré-escapular e inguinal superficial. O exame histopatológico apontou a presença de granulomas em 8 (20,00%) animais. Dos 12 caprinos, 1 (8,33%) foi positivo no cultivo de micobactérias, e pelo método PRA o isolado foi classificado como pertencente ao complexo M. tuberculosis. Dois (7,14%) ovinos foram positivos para a presença de micobactérias ambientais. Houve isolamento de Corynebacterium pseudotuberculosis em 8 (66,66%) caprinos e em 17 (60,71%) ovinos, e isolamento simultâneo de micobactérias e C. pseudotuberculosis em 1 (8,33%) caprino e 1 (3,57%) ovino. O isolamento de micobactéria do complexo M. tuberculosis em caprinos no presente trabalho levanta preocupações do ponto de vista de saúde pública, uma vez que profissionais envolvidos na manipulação destes animais, bem como a população consumidora de carne [...]

Controle da eficácia de bacterinas antileptospirose: relação entre os resultados dos testes de inibição de crescimento de leptospiras in vitro com os do desafio in vivo em hamsters / Efficacy of anti-leptospirosis bacterines: relation between the results of the in vitro growth inhibition test and the potency test, in vivo, with challenge in hamsters

Foi efetuada a comparação em hamsters da proteção conferida e dos níveis de anticorpos induzidos por duas bacterinas comerciais antileptospirose. Os ensaios empregados foram o teste oficial de potência com desafio (TP), o ensaio proposto, teste de inibição de crescimento de leptospiras in vitro (ICLIV) e a soroaglutinação microscópica (SAM). O protocolo de imunização foi representado por duas aplicações individuais de 0,25 mL das bacterinas, puras ou de suas diluições geométricas de razão dois variando de 200 a 51.200 para a bacterina A e de 200 a 3.200 para a bacterina B, por via subcutânea com o intervalo de 15 dias. Decorridos 15 dias da segunda aplicação de vacina, um grupo de animais foi desafiado com 0,2 mL de cultivos de leptospiras, por indivíduo, respectivamente dos sorovares Canicola (bacterinas A e B) ou Kennewicki (bacterina A). Os números de doses infectantes empregados nos desafios foram de 100 e 631 respectivamente, para os sorovares Canicola e Kennewicki. Decorridos 21 dias do desafio, os grupos de animais utilizados nos testes de ICLIV e SAM foram sangrados e os seus soros foram reunidos em pools (n = 5). No TP, adotando-se os critérios internacionais, as bacterinas foram aprovadas. A comparação do desempenho das bacterinas para os sorovares adotados, segundo sua concentração, por meio das proporções de animais sobreviventes ao TP e a média dos títulos de anticorpos identificados no teste de ICLIV, indicou que um título igual ou superior a 0,77 log corresponde ao nível de aprovação da bacterina no TP.

It was performed a comparison between the protection afforded in hamsters and the antibody levels induced by two commercial vaccines against leptospirosis. The assays used were the official challenge test (TP), the in vitro leptospires growth inhibition test (ICLIV) and microscopic agglutination test (MAT). The immunization protocol consisted of two single applications, 15 days from each other, of 0.25 mL of the bacterins, pure or its two-fold serial dilutions: 200 to 51,200 for bacterin A and 200 to 3.200 bacterin B, both of them administered subcutaneously. A group of animals was challenged, after 15 days from the second vaccine application, with 0.2 mL/animal of live leptospire cultures, with Canicola (bacterin A and B) or Kennewicki (bacterin A) serovars. The numbers of infective doses employed in the challenges were 100 and 631 for Canicola and Kennewicki serovars, respectively. After 15 days from the second vaccine dose the groups of animals used in ICLIV and SAM tests were bled and their sera were collected in pools (n = 5). In TP, adopting the criteria established by the Code Federal Regulation, both bacterins were approved. The comparison of the performance of the tested bacterins with the adopted serovars, according to its concentration, by the proportions of surviving animals to the challenge assay and the average of the neutralizing antibodies titers, established a neutralizing antibodies titer equal or higher than 0.77 log corresponding with the bacterin level of approval in the potency assay.

Mycobacterium bovis infection in goats from the Northeast region of Brazil

A total of 8,058 male and female mixed-breed goats and 1-4 years of age were slaughtered over a period of 7 months at the public slaughterhouse of Patos city, Paraíba state, in the Northeast region of Brazil; 822 animals were inspected for gross lesions of tuberculosis, and 12 (1.46 percent) had lesions suggestive of tuberculosis in the mammary gland, lungs, liver and mediastinal, mesenteric, submandibular, parotid and prescapular lymph nodes. Presence of granulomatous lesions was confirmed in the submandibular lymph node of one (8.3 percent) goat at the histopathological examination and at the mycobacterium culture the same sample was confirmed positive. Isolate was confirmed as belonging to the M. tuberculosis complex by PCR restriction enzyme analysis (PRA). Spoligotyping identified the isolate into spoligotype SB0295 on the M. bovis Spoligotype Database website (www.mbovis.org), and it was classified as M. bovis. The occurrence of M. bovis in goats in this study suggests that this species may be a potential source of infection for humans and should be regarded as a possible problem in the advancement of control and eradication program for bovine tuberculosis in Brazil.

Exposure of free-ranging wild carnivores, horses and domestic dogs to Leptospira spp in the northern Pantanal, Brazil

Leptospirosis is a zoonotic disease affecting most mammals and is distributed throughout the world. Several species of domestic and wild animals may act as reservoirs for this disease. The purpose of this study was to assess the exposure of free-ranging wild carnivores, horses and domestic dogs on a private reserve located in the northern Pantanal (Brazil) and the surrounding areas to Leptospira spp from 2002-2006, 75 free-ranging wild carnivores were captured in the Pantanal and serum samples were collected. In addition, samples from 103 domestic dogs and 23 horses in the region were collected. Serum samples were tested for the presence of Leptospira antibodies using the microscopic agglutination test. Thirty-two wild carnivores (42.7 percent) were considered positive with titres > 100, and 18 domestic dogs (17.5 percent) and 20 horses (74.1 percent) were also found to be positive. Our study showed that horses, dogs and several species of free-ranging wild carnivores have been exposed to Leptospira spp in the Pantanal, suggesting that the peculiar characteristics of this biome, such as high temperatures and an extended period of flooding, may favour bacterial persistence and transmission. In this region, wild carnivores and horses seem to be important hosts for the epidemiology of Leptospira species.