RESUMO
A simple and reliable indirect enzyme-linked immunosorbent assay for detection of antibodies directed against a major bovine viral diarrhea virus (BVDV) immunogen, the E2 glycoprotein (tE2-ELISA), has been developed using the recombinant C-terminal truncated E2 glycoprotein (tE2) expressed in a Drosophila melanogaster system. This strategy demonstrated that tE2 is secreted efficiently in the supernatant, no purification steps are necessary, it is easy to produce and carries out the post translational modifications necessary to preserve its native conformation. Preliminary analysis of 183 cattle serum samples using tE2-ELISA showed a 98% specificity and a 100% sensitivity compared with the standard homologous BVDV virus neutralization test. The results also showed that the tE2 is immunoreactive because the conformation and antigenicity of the original E2 are maintained to a large extent. To our knowledge this is the first study report of the recombinant tE2 of BVDV expressed in D. melanogaster system as an antigen for ELISA.
Assuntos
Anticorpos Antivirais/sangue , Antígenos Virais/imunologia , Vírus da Diarreia Viral Bovina/imunologia , Ensaio de Imunoadsorção Enzimática , Proteínas do Envelope Viral/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Monoclonais/imunologia , Antígenos Virais/biossíntese , Antígenos Virais/isolamento & purificação , Bovinos , Vírus da Diarreia Viral Bovina/genética , Drosophila melanogaster , Testes de Neutralização , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/isolamento & purificação , Sensibilidade e Especificidade , Proteínas do Envelope Viral/biossíntese , Proteínas do Envelope Viral/isolamento & purificaçãoRESUMO
Auto-processing of the non-structural polypeptide 3ABC of foot and mouth disease virus (FMDV) expressed in Escherichia coli-BL21-DE3 was prevented by mutating either four glutamic acid residues at the 3A/3B1, 3B1/2, 3B2/3 and 3B3/3C junctions (3ABCtet) or a single cysteine residue at position 383 within the 3C domain (3ABCm). Independent expression of 3ABC and 3ABCtet genes induced expression of chaperone DnaK and degradation of ribosomal S1 protein in E. coli. They also induced cleavage of nucleosomal histone H3 when transiently expressed in BHK21 cells. 3ABCtet, 3ABCm, 3AB and 3A proteins concentrated in the perinuclear region suggesting that peptide sequences within the 3A domain specify intracellular targeting of 3ABC in BHK-21 cells. We propose that 3ABC molecules localized in the nuclear periphery are a source of protease 3C activity and are responsible for histone H3 processing during FMDV infections.
Assuntos
Cisteína Endopeptidases/metabolismo , Vírus da Febre Aftosa/patogenicidade , Histonas/metabolismo , Peptídeos/metabolismo , Proteínas não Estruturais Virais/metabolismo , Proteínas Virais/metabolismo , Proteases Virais 3C , Animais , Linhagem Celular , Cricetinae , Cisteína Endopeptidases/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Vírus da Febre Aftosa/enzimologia , Vírus da Febre Aftosa/genética , Proteínas não Estruturais Virais/genética , Proteínas Virais/genéticaRESUMO
Feces from Triatoma infestans (Klug) infected with TrV showed a large number of well-preserved viral particles when examined by electron microscopy. No viral particles were observed in suspensions of feces uninfected insects. Fecal suspensions inoculated parenterally into uninfected triatomines killed the insects within 36 h, showing that infective TrV is present in the feces of infected insects. It also is demonstrated that T. infestans becomes infected with TrV while feeding on contaminated chickens, and all the chickens used to feed a colony of triatomines infected with TrV showed high anti-TrV titer in their sera, although no TrV replication could be demonstrated in chickens. Oral infection of T. infestans by contaminated feces probably contributes to virus dispersal in nature. This observation provides the rationale for the potential use of TrV as a biological control agent.
Assuntos
Vírus de Insetos , Picornaviridae , Triatoma/virologia , Animais , Anticorpos Antivirais/imunologia , Galinhas , Fezes/virologia , Vírus de Insetos/fisiologia , Picornaviridae/fisiologiaRESUMO
Triatoma virus (TrV) is the only virus described to date that infects triatomines, and has previously been considered to be a member of the family Picornaviridae on the basis of physico-chemical properties. The genome of TrV was sequenced completely (9010 nt). Analysis of the sequence revealed the presence of two large open reading frames (ORFs). The predicted amino acid sequence of ORF1 (nt 549-5936) showed significant similarity to the non-structural proteins of several animal and plant RNA viruses. This ORF product contains sequence motifs characteristic of RNA-dependent RNA polymerases (RdRp), cysteine proteases and RNA helicases. ORF1 is preceded by 548 nucleotides of non-coding RNA and the two ORFs are separated by 172 nucleotides of non-coding RNA. Direct N terminus sequence analysis of two capsid proteins showed that ORF2 (nt 6109-8715) encodes the structural proteins of TrV. The predicted amino acid sequence of ORF2 is very similar to the corresponding regions of Drosophila C virus, Plautia stali intestine virus, Rhopalosiphum padi virus and Himetobi P virus and to a partial sequence from the 3' end of the cricket paralysis virus genome. All of these viruses have a novel genome organization and it has been proposed that they are not members of the Picornaviridae, as previously thought, but belong to a new virus family. On the basis of similarities of genome organization, we propose that TrV also belongs to this new virus family.
Assuntos
Vírus de RNA/classificação , Vírus de RNA/genética , Triatoma/virologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Genoma Viral , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
In this work we report four different destructive and non-destructive methods for detecting picorna-like virus particles in triatomines. The methods are based on direct observation under transmission electron microscope and they consist of four ways to prepare samples of presumable infected material. The samples are prepared processing dead or alive insect parts, or even dry or fresh insect feces. The methods can be used as analytical or preparative techniques, for quantifying virus infection and checking virus integrity as well. In this work the four methods are applied in order to detect Triatoma virus (TrV) particles in T. infestans colonies.
Assuntos
Animais , Feminino , Vírus de Insetos/isolamento & purificação , Picornaviridae/isolamento & purificação , Triatominae/virologia , Microscopia Eletrônica/métodosRESUMO
The anti-foot and mouth disease virus (FMDV) serum antibody activity of protected and non protected animals immunized with inactivated FMDV originated in either bovine tongue tissue (BTTV vaccines) or BHK-21 cell suspension cultures (BHKV vaccines) was evaluated. The results show that 80-100% of the BTTV immunized and only 40-60% of the BHKV immunized animals with liquid-phase blocking sandwich ELISA (lp ELISA) serum titres of 1.5-1.7 U, were protected against the challenge with any of the four infectious FMDV argentine reference strains. This difference becomes almost marginal among BTTV and BHKV vaccinated animals with a strong anti-FMDV humoral response (i.e. lp ELISA titres > or = 1.95 U). Isotyping of the anti-FMDV response in immunized cattle with low lp ELISA titres revealed that BTTV vaccines were able to induce remarkably higher anti-FMDV IgG1 titres than their BHKV counterparts (i.e. mean titres of 1.95 and 1.35 U. respectively). This difference in specific IgG1 serum levels induced by BTTV and BHKV vaccines seems to be also limited to those animals with low anti-FMDV lp ELISA titres. These results together with the fact that the specific serum IgG1, but not the IgG2, isotype response of 219 vaccinated animals correlates almost linearly with their capacity to pass the challenge, suggests that the superior performance of BTTV vaccines is close related to their ability to raise a stronger anti-FMDV IgG1 response than BHKV vaccines.
Assuntos
Anticorpos Antivirais/sangue , Aphthovirus/imunologia , Isotipos de Imunoglobulinas , Vacinas Sintéticas/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Antivirais/classificação , Formação de Anticorpos , Bovinos , Linhagem Celular , Cricetinae , Ensaio de Imunoadsorção Enzimática , Imunoglobulina G/sangue , Língua/citologia , Vacinas de Produtos Inativados/imunologiaRESUMO
An oligodeoxynucleotide coding for amino acids 139 through 149 of antigenic site A (ASA) of the VP1 capsid protein of the foot-and-mouth disease virus C3 serotype (FMDV C3) was inserted into three different in-frame sites of the vesicular stomatitis virus New Jersey serotype (VSV-NJ) glycoprotein (G) gene cDNA present in plasmid pKG97 under control of the bacteriophage T7 polymerase promoter. Transfection of these plasmids into CV1 cells coinfected with the T7 polymerase-expressing vaccinia virus recombinant vTF1-6,2 resulted in expression of chimeric proteins efficiently reactive with both anti-FMDV and anti-VSV G antibodies. However, in vitro translation of transcripts of these VSV-G/FMDV-ASA chimeric plasmids resulted in proteins that were recognized by anti-G serum but not by anti-FMDV serum, indicating a requirement for in vivo conformation to expose the ASA antigenic determinant. Insertion of DNA coding for a dimer of the ASA unidecapeptide between the VSV-NJ G gene region coding for amino acids 160 and 161 gave rise to a chimeric ASA-dimer protein designated GF2d, which reacted twice as strongly with anti-FMDV antibody as did chimeric proteins in which the ASA monomer was inserted in the same position or two other G-gene positions. For even greater expression of chimeric VSV-G/FMDV-ASA proteins, plasmid pGF2d and a deletion mutant p(delta)GF2d (G protein deleted of 324 C-terminal amino acids) were inserted into baculovirus vectors expressing chimeric proteins GF2d-bac and deltaGF2d-bac produced in Sf9 insect cells. Mice vaccinated with three booster injections of 30 microg each of partially purified GF2d-bac protein responded by enzyme-linked immunosorbent assay with FMDV antibody titers of 1,000 units, and those injected with equivalent amounts of deltaGF2d-bac protein showed serum titers of up to 10,000 units. Particularly impressive were FMDV neutralizing antibody titers in serum of mice vaccinated with deltaGF2d-bac protein, which approached those in the sera of mice vaccinated with three 1-microg doses of native FMDV virions. Despite excellent reactivity with native FMDV, the anti-deltaGF2d-bac antibody present in vaccinated mouse serum showed no capacity to bind to sodium dodecyl sulfate (SDS)-denatured FMDV virions and only minimal reactivity with VP1 protein by Western blotting (immunoblotting) after SDS-polyacrylamide gel electrophoresis. It was also shown in a competitive binding assay that a synthetic ASA unidecapeptide, up to concentrations of 200 microg/ml, was quite limited in its ability to inhibit binding of anti-deltaGF2-bac antibody to native FMDV virions. These results suggest that the chimeric VSV-G/FMDV-ASA proteins mimic the capacity of FMDV to raise and react with neutralizing antibodies to a restricted number of ASA conformations present on the surface of native FMDV particles.
Assuntos
Antígenos Virais/imunologia , Aphthovirus/imunologia , Capsídeo/imunologia , Glicoproteínas de Membrana , Vesiculovirus/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Antivirais/imunologia , Antígenos Virais/genética , Aphthovirus/genética , Baculoviridae/genética , Capsídeo/genética , Proteínas do Capsídeo , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Febre Aftosa/imunologia , Vetores Genéticos , Imunogenética , Testes de Neutralização , Testes de Precipitina , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Spodoptera/citologia , Vesiculovirus/genética , Proteínas do Envelope Viral/genéticaRESUMO
The lowest expected protection (LEP) at a 95% confidence of 245 foot and mouth disease (FMD) commercial vaccines was calculated from the titres of liquid-phase blocking sandwich ELISA (lpELISA) of cattle sera obtained from 3920 animals at 60 days post-vaccination (d.p.v.) and challenged with live virus at 90 d.p.v. It was found that LEP evaluation is highly specific (i.e. it is able to predict the failure in 100% of the cases) although its ability to predict the challenge (PG test) approval (i.e. sensitivity) comprised only 65% of the vaccines that passed the trial. It was possible, nevertheless, to improve the sensitivity of the evaluation by using an alternative coefficient (Ro), exclusively dependent on the number of animals exhibiting the highest and lowest lpELISA titres in a particular vaccine trial. This coefficient was capable of predicting the PG approval of 90% of the vaccines, yet maintaining acceptable levels of safety (87% of specificity). Based on these results and as a first step towards the replacement of the challenge protocol in Argentina, we propose a swift approval for commercialization of FMD vaccines which are able to reach the highly restricting LEP passmark of 82%, and the rejection of those not reaching the 50% LEP limit. More extensive experience with this new protocol will allow a finer adjustment of the LEP and Ro values and to set more precisely the cut-off points for direct approval or disapproval of vaccines by lpELISA, eliminating the use of live FMDV in the field.
Assuntos
Aphthovirus/imunologia , Febre Aftosa/prevenção & controle , Vacinas Virais/uso terapêutico , Animais , Anticorpos Antivirais/sangue , Bovinos , Ensaio de Imunoadsorção Enzimática , Valor Preditivo dos Testes , Sensibilidade e EspecificidadeRESUMO
Specific serum activity levels against four reference strains of foot-and-mouth disease virus (FMDV) were evaluated from 1634 animals vaccinated with commercial quadrivalent oil vaccines and from 746 unvaccinated, naive animals, using the liquid-phase blocking sandwich ELISA (lpELISA) test. Cows from the FMDV-free area of Argentina were tested for the absence of specific FMDV antibodies (sp FMDV Abs) and those showing lpELISA titres < 1.0 were grouped in lots of 16 animals. They were vaccinated and challenged at 90 days postvaccination (DPV) with one of four virus strains used for vaccine production and control (prototype strains). Serum samples from vaccinated and control cattle were collected 60 and 90 DPV and the level of sp FMDV Abs was determined by lpELISA. Animals were examined for clinical signs of disease. Results show that serum lpELISA titre levels directly correlate with the percentage of protected animals. It was seen that 100, 98, 93 and 87% of the vaccinated cattle with antibody titre levels > or = 2.1 were protected against challenge with serotypes C85, A87,01 Cas and A79, respectively. Evidence is also presented of seroconversion in a sample of 3-5-month-old calves vaccinated in the field, showing lpELISA titres compatible with protection against the four vaccine viruses as long as 150 DPV. Results reported in this paper strongly support the use of the lpELISA test for a rapid and reliable evaluation of the efficacy of FMDV commercial vaccines as well as for the assessment of the immunological status of cattle in FMDV-free and enzootic regions of South America.
Assuntos
Anticorpos Antivirais/sangue , Aphthovirus/imunologia , Ensaio de Imunoadsorção Enzimática/veterinária , Febre Aftosa/prevenção & controle , Vacinas Virais/imunologia , Adjuvantes Imunológicos , Animais , Argentina , Bovinos , Febre Aftosa/imunologia , Reprodutibilidade dos Testes , VacinaçãoRESUMO
Bovine rotavirus T449 was isolated from feces of a calf with diarrhea. Serological characterization by serotype-specific monoclonal antibodies showed that the T449 virus belonged to serotype 1. This is the first report of a bovine rotavirus that does not belong to serotype 6, 8, or 10. The serotype 1 designation was confirmed by using an immunoperoxidase focus neutralization assay. The gene encoding the major neutralization antigen (VP7) was cloned and its nucleotide sequence was determined. The sequence obtained was 1062 bp in length and contained an open reading frame corresponding to 326 amino acid residues. Comparative analysis of the deduced amino acid sequence with the corresponding sequence of the human serotype 1 rotavirus strain, Wa, revealed a 90% identity. When compared to the predicted amino acid sequence of VP7 protein of the other serotypes an overall divergence of 20 to 25% was detected. These data show that the serological typing agrees with the result of the genetic analysis.
Assuntos
Antígenos Virais , Proteínas do Capsídeo , Capsídeo/genética , Capsídeo/imunologia , Genes Virais , Rotavirus/imunologia , Proteínas Estruturais Virais/genética , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/imunologia , Bovinos , Doenças dos Bovinos/microbiologia , Diarreia/veterinária , Dados de Sequência Molecular , Rotavirus/genética , Alinhamento de Sequência , SorotipagemRESUMO
A set of antisera specific for each viral polypeptide of foot-and-mouth disease virus was used to provide a full comparison of polypeptides of two strains attenuated for cattle with respect to their parental virulent strains. Both attenuated strains, belonging to serotypes O1 Campos and C3 Resende, were obtained through serial passages of the corresponding virulent strains in chicken embryos. Although mutations were scattered throughout the genome, both attenuated strains showed an electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of viral polypeptide 3A faster than that of their respective wild-type strains. To determine the nature of this alteration, the nucleotide sequences of the genomic region encoding this polypeptide were determined. Comparative sequence analysis of wild-type and attenuated strains revealed 57 and 60 nucleotide deletions in the attenuated strains O1 Campos and C3 Resende, respectively. These studies, in conjunction with our previous analysis of recombinant viruses between wild-type and attenuated strains, which concluded that the major determinants of attenuation are located in the 3' half of the viral genome, strongly suggest that the alteration in polypeptide 3A of the attenuated strains is important for their reduced virulence in cattle.
Assuntos
Aphthovirus/genética , Peptídeos/genética , Animais , Aphthovirus/imunologia , Aphthovirus/patogenicidade , Sequência de Bases , Bovinos , Linhagem Celular , Deleção Cromossômica , Genes Virais , Soros Imunes , Dados de Sequência Molecular , Peptídeos/análise , Vacinas Atenuadas , VirulênciaRESUMO
Rotavirus, Cryptosporidium sp, and Salmonella spp. were investigated in the faeces of 452 diarrhoeic calves from 36 beef and 33 dairy herds. Animals surveyed were from a few days of age up to approximately 1 month of life. Enterotoxigenic Escherichia coli (ETEC) was studied in 212 calves, aged 15 days or less. The animals were from the Provinces of Buenos Aires (59% of the calves), Córdoba (18%), Santa Fe (16%), Entre Ríos (5%) and La Pampa (2%). A minimum of 4 calves were sampled on each farm. In beef calves rotavirus was excreted by 45.1% of the animals. Cryptosporidium by 30.5% and Sàlmonella serovars Arechabaleta, Livingstone, Panama and Typhimurium by 1.9%. In dairy calves Cryptosporidium was excreted by 29.6%, rotavirus by 23% and Salmonella serovar Dublin by 1.6%, ETEC was not detected in any calf. Rotavirus was the most widespread agent, detected in 32 (88.9%) beef herds and excreted by more than 50% of the calves in half of these herds. In contrast, rotavirus was only detected in 19 (57.5%) dairy herds and was excreted by more than 50% of the calves in 6 of these herds. Crytosporidium oocysts were identified in 27 (75%) beef and in 23 (69.7%) dairy farms. Salmonellosis due to serovar Dublin was associated with diarrhoea in 2 dairy herds. Concurrent infection with two or three agents occurred in 36 (8%) calves and 38 (55.1%) farms; the combination rotavirus-Cryptosporidium was found in 32 (6.9%) calves an in 33 (47.8) farms.
Assuntos
Doenças dos Bovinos/microbiologia , Diarreia/veterinária , Animais , Argentina/epidemiologia , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Criptosporidiose/epidemiologia , Diarreia/epidemiologia , Diarreia/microbiologia , Diarreia/parasitologia , Surtos de Doenças/veterinária , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Fezes/microbiologia , Fezes/parasitologia , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/veterinária , Salmonelose Animal/epidemiologiaRESUMO
Two porcine rotavirus strains (CN86 and CC86) isolated during an epidemiological survey of diarrhoea in swine in Argentina were studied because of several unique characteristics. Both these strains were isolated and cloned from the same faecal sample and the electrophoretic migration of 10 of their 11 genomic dsRNA genomic segments in polyacrylamide gels was identical, but strain CC86 had a supershort electropherotype. We analysed biochemical, serological and biological properties of both viruses. In vitro translation of genome segment 11 RNAs showed that both viruses produced a polypeptide with an apparent Mr of 26K. No differences in any of the other virus-induced proteins made in infected MA104 cells were found on one- and two-dimensional gels for either strain. In addition, the serotype and the subgroup specificities of both viruses were identical (group A, subgroup I, serotype 5). These results suggest that the rearranged strain was probably generated from the standard one and that the coding capacity of the rearranged segment was conserved. Consistent with this hypothesis, primer extension analysis revealed that the supershort strain had a rearrangement involving partial duplication of genomic segment 11. Biological studies showed differences between these viruses. The rearranged strain (CC86) produced larger plaques in monolayers of MA104 cells and outgrew the standard strain (CN86) when cells were coinfected with both viruses at different relative concentrations and different m.o.i. The possibility that large plaque formation and efficient virus replication can be influenced by the products of genomic segment 11, in addition to segment 4, is discussed.
Assuntos
Rearranjo Gênico , RNA de Cadeia Dupla/análise , RNA Viral/análise , Rotavirus/genética , Animais , Eletroforese em Gel de Poliacrilamida , Fezes/microbiologia , Genes Virais , Fenótipo , Biossíntese de Proteínas , Rotavirus/crescimento & desenvolvimento , Suínos , Ensaio de Placa ViralRESUMO
Rotavirus, Cryptosporidium sp. y Salmonella spp. fueron investigados en las heces de 452 terneros diarreicos provenientes de 36 rodeos de cría y 33 de tambo. Los animales muestreados tenían desde pocos días de vida hasta aproximadamente 1 mes de edad. Escherichia coli enterotoxigénica (ETEC) fue buscada en 212 terneros de 15 o menos días de edad. Los animales provenían de las Provincias de Buenos Aires (59%) de los terneros), Córdoba (18%), Santa Fe (16%), Entre Ríos (5%) y la Pampa (2%). Um mínimo de 4 terneros fue muestreado en cada establecimiento. En terneros de cría, rotavirus fue excretado por el 45,1% de los animales Cryptosporidium por el 30,5% y Salmonela serovariedades Arechabaleta, Livingstone, Panama y Typhimurium por el 1,9% (Cuadro 1). En terneros de tambo Cryptossporidium fue excretado per el 29,6%, rotavirus por el 23% y Salmonella serovariedad Dublin por el 1,6%. ETEC no fue detectado en ningún ternero. Rotavirus fue el agente más difundido, detectado en 32(88,9%) rodeos de cría (Cuadro 2) y excretado por más del 50% de los terneros en la mitad de esos rodeos. En contraste rotavirus fue solamente detectado en 19(57,5%) tambos y fue excretado por más del 50% de los terneros en 6 de esos rodeos. Se identificaron oocistos de Cryptosporidium en 27(75%) rodeos de cría y en 23(69,7%) tambos. La salmonelosis por la serovariedad Dublin se asoció con diarrea en 2 tambos. Infecciones concurrentes con dos o tres agentes ocurrieron en 36(8%) terneros y en 38(55,1%) establecimientos; la combinación rotavirus-Cryptosporidium se encontró en 31(6,9%) terneros y en 33(47,8) establecimientos (AU)
Assuntos
Estudo Comparativo , Animais , Bovinos , Diarreia/veterinária , Doenças dos Bovinos/microbiologia , Diarreia/epidemiologia , Diarreia/microbiologia , Diarreia/parasitologia , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/veterinária , Salmonelose Animal/epidemiologia , Fezes/microbiologia , Fezes/parasitologia , Criptosporidiose/epidemiologiaRESUMO
Rotavirus, Cryptosporidium sp, and Salmonella spp. were investigated in the faeces of 452 diarrhoeic calves from 36 beef and 33 dairy herds. Animals surveyed were from a few days of age up to approximately 1 month of life. Enterotoxigenic Escherichia coli (ETEC) was studied in 212 calves, aged 15 days or less. The animals were from the Provinces of Buenos Aires (59
of the calves), Córdoba (18
), Santa Fe (16
), Entre Ríos (5
) and La Pampa (2
). A minimum of 4 calves were sampled on each farm. In beef calves rotavirus was excreted by 45.1
of the animals. Cryptosporidium by 30.5
and SOlmonella serovars Arechabaleta, Livingstone, Panama and Typhimurium by 1.9
. In dairy calves Cryptosporidium was excreted by 29.6
, rotavirus by 23
and Salmonella serovar Dublin by 1.6
, ETEC was not detected in any calf. Rotavirus was the most widespread agent, detected in 32 (88.9
) beef herds and excreted by more than 50
of the calves in half of these herds. In contrast, rotavirus was only detected in 19 (57.5
) dairy herds and was excreted by more than 50
of the calves in 6 of these herds. Crytosporidium oocysts were identified in 27 (75
) beef and in 23 (69.7
) dairy farms. Salmonellosis due to serovar Dublin was associated with diarrhoea in 2 dairy herds. Concurrent infection with two or three agents occurred in 36 (8
) calves and 38 (55.1
) farms; the combination rotavirus-Cryptosporidium was found in 32 (6.9
) calves an in 33 (47.8) farms.
RESUMO
Rotavirus, Cryptosporidium sp. y Salmonella spp. fueron investigados en las heces de 452 terneros diarreicos provenientes de 36 rodeos de cría y 33 de tambo. Los animales muestreados tenían desde pocos días de vida hasta aproximadamente 1 mes de edad. Escherichia coli enterotoxigénica (ETEC) fue buscada en 212 terneros de 15 o menos días de edad. Los animales provenían de las Provincias de Buenos Aires (59%) de los terneros), Córdoba (18%), Santa Fe (16%), Entre Ríos (5%) y la Pampa (2%). Um mínimo de 4 terneros fue muestreado en cada establecimiento. En terneros de cría, rotavirus fue excretado por el 45,1% de los animales Cryptosporidium por el 30,5% y Salmonela serovariedades Arechabaleta, Livingstone, Panama y Typhimurium por el 1,9% (Cuadro 1). En terneros de tambo Cryptossporidium fue excretado per el 29,6%, rotavirus por el 23% y Salmonella serovariedad Dublin por el 1,6%. ETEC no fue detectado en ningún ternero. Rotavirus fue el agente más difundido, detectado en 32(88,9%) rodeos de cría (Cuadro 2) y excretado por más del 50% de los terneros en la mitad de esos rodeos. En contraste rotavirus fue solamente detectado en 19(57,5%) tambos y fue excretado por más del 50% de los terneros en 6 de esos rodeos. Se identificaron oocistos de Cryptosporidium en 27(75%) rodeos de cría y en 23(69,7%) tambos. La salmonelosis por la serovariedad Dublin se asoció con diarrea en 2 tambos. Infecciones concurrentes con dos o tres agentes ocurrieron en 36(8%) terneros y en 38(55,1%) establecimientos; la combinación rotavirus-Cryptosporidium se encontró en 31(6,9%) terneros y en 33(47,8) establecimientos
Assuntos
Animais , Bovinos , Diarreia/veterinária , Doenças dos Bovinos/microbiologia , Criptosporidiose/epidemiologia , Diarreia/epidemiologia , Diarreia/microbiologia , Diarreia/parasitologia , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Fezes/microbiologia , Fezes/parasitologia , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/veterinária , Salmonelose Animal/epidemiologiaRESUMO
We have assessed the potency of an inactivated oil-adjuvanted rotavirus vaccine in beef herds in Argentina. Two different vaccine trials were conducted. In a small-scale experimental trial, involving 21 pregnant cows (13 vaccinated and eight unvaccinated controls), a significant increase in neutralizing antibody titres against different serotypes of bovine rotaviruses was found in both the colostrum and serum of vaccinated cows compared with that of unvaccinated controls. Seven days after birth, half of the calves born to vaccinated dams or to control cows were challenged with live virulent virus whereas the other half of both groups were left in contact with the infected calves in order to mimic a natural field challenge. Although no statistically significant differences in the rate of protection were observed among the different groups of animals, a larger number of vaccinated calves were protected in comparison with their controls, particularly where animals in contact with infected calves were concerned. Secondly, a large-scale field trial was carried out in 17 beef herds involving a total of 4066 vaccinated pregnant cows. In 11 farms morbidity and mortality in calves from vaccinated cows were compared with historical data from the previous 3 years at the same locations. In the other six herds, control groups were used to compare data of the same year: 1540 cows were vaccinated and 2700 were left as controls. Taking into account the previous and current incidence of diarrhoea, morbidity and mortality were significantly reduced in 16 of the 17 beef herds tested. Vaccine effectiveness was also evident in farms where other enteropathogens such as cryptosporidium and coronaviruses were present, together with rotavirus.
Assuntos
Doença das Mucosas por Vírus da Diarreia Viral Bovina/prevenção & controle , Doenças dos Bovinos/prevenção & controle , Rotavirus/imunologia , Vacinas de Produtos Inativados/imunologia , Adjuvantes Imunológicos , Animais , Argentina , Doença das Mucosas por Vírus da Diarreia Viral Bovina/epidemiologia , Doença das Mucosas por Vírus da Diarreia Viral Bovina/mortalidade , Bovinos , Feminino , Humanos , Imunidade Materno-Adquirida , Lactente , Recém-Nascido , Gravidez , Vacinas de Produtos Inativados/administração & dosagemRESUMO
Fecal samples from 156 diarrheic piglets were collected from several herds located in two main breeding areas of Argentina. Rotaviruses were detected in 60 samples (38.4%) by polyacrylamide gel electrophoresis and in 55 samples by a group A-specific enzyme-linked immunosorbent assay (ELISA). All samples which were positive by polyacrylamide gel electrophoresis and negative by ELISA had elicited atypical electropherotypes resembling those of group B or C. ELISA-positive samples showing genome rearrangements were also detected (R.C. Bellinzoni, N.M. Mattion, O.R. Burrone, S.A. González, J.L. La Torre, and E.A. Scodeller, J. Clin. Microbiol. 25:952-954, 1987; N.M. Mattion, S.A. González, O.R. Burrone, R.C. Bellinzoni, J.L. La Torre, and E.A. Scodeller, J. Gen. Virol. 69:695-698, 1988). By subgrouping with monoclonal antibodies, it was found that of 32 positive samples, 13 belonged to subgroup I, 2 belonged to subgroup II, 2 samples had both specificities, and 15 samples were neither subgroup I nor subgroup II (non-I/II). In addition, 10 samples were adapted to grow in tissue culture, cloned, and serotyped by means of neutralization assays. Two samples were classified as serotype 5, and none of them were classified as serotype 4. The other strains showed only a one-way relationship with serotype 5 and can be tentatively classified as new porcine serotypes. Two samples with rearranged genomes had a one-way relationship with antiserum to human strain 69M, which displays a supershort electropherotype and was classified as a new human serotype (S. Matsuno, A. Hasegawa, A. Mukoyama, and S. Inouye, J. Virol. 54:623-624, 1985). At one farm, similar rearranged strains were detected during three successive years. Serotype changes were found between the isolates of the first and the second year, suggesting that a high degree of antigenic variability went on during continuous circulation of these strains in the field.
Assuntos
Variação Antigênica , Rotavirus/imunologia , Suínos/microbiologia , Animais , Antígenos Virais/imunologia , Argentina , Diarreia/microbiologia , Diarreia/veterinária , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Fezes/microbiologia , RNA Viral/análise , Rotavirus/genética , Rotavirus/isolamento & purificação , Infecções por Rotavirus/microbiologia , Infecções por Rotavirus/veterinária , Sorotipagem , Doenças dos Suínos/microbiologiaRESUMO
Some properties of Triatoma virus (TrV), a picorna-like virus recently isolated from Triatoma infestans, have been studied. Electron microscopic observations of purified viral preparations showed the presence of non-enveloped viral particles 30 nm in diameter. The sedimentation coefficient of virus particles was about 165S and the buoyant density in CsCl was 1.39 g/ml. The viral genome was composed of one single-stranded RNA molecule with an Mr of 3 x 10(6). Three major polypeptides with Mr values of 39K, 37K and 33K and a minor one of about 45K were found in the virus particle. TrV particles contain about 35% RNA and 65% protein by weight. These data support the classification of this virus in the family Picornaviridae.