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The objective of this study was to analyze the immune responses of bucks to small ruminant lentivirus (SRLV) with a focus on the reproductive system of males with recent and chronic infection. A total of 12 bucks were selected, six seronegative and six seropositive with chronic natural infection for more than 18 months (chronic infection group). After selecting the animals, the six seronegative males were intravenously inoculated with caprine arthritis-encephalitis virus (CAEV)-Co viral strain at a titer of 10-5,6 TCID50/mL. After viral inoculation, this group was called the recent infection group and was monitored weekly with the chronically infected group for 180 days with blood serum and seminal plasma Western Blot (WB) analysis. Of the animals with chronic SRLV infection, 18.94% (50/264) showed anti-SRLV antibodies in at least one of the samples, and 81.06% (214/264) were negative. Anti-SRLV antibodies were detected in 27.27% (36/132) of the blood serum samples from this group, while 10.60% (14/132) were reactive in the seminal plasma WB test. The animals inoculated with CAEV-Co became seropositive after the third week of viral inoculation. In this group, 31.06% (41/132) of seminal plasma samples had anti-SRLV antibodies, and of these, 70.73% (29/41) coincided with blood serum results. Of the remaining 29.27% (12/41), the seminal plasma sample of only three animals (RIA2, RIA3, and RIA5) had anti-SRLV antibodies. One of the animals with a recent infection presented anti-SRLV antibodies only in seminal plasma samples, possibly due to virus compartmentalization. Intermittent viral shedding was observed in both biological samples, regardless of the infection stage. The immune response in bucks with recent SRLV infection is more significant than in chronically infected animals. Regardless of the stage of infection, there is a fluctuation in antibody levels, therefore, this creates a risk of false-negative samples when performing the diagnosis.

O objetivo desse estudo foi analisar a resposta imunológica aos lentivírus de pequenos ruminantes (LVPR) com enfoque no sistema reprodutor de machos com infecção recente e crônica. Para isso, foram selecionados 12 reprodutores caprinos, sendo seis soronegativos e seis soropositivos com infecção natural crônica há mais de 18 meses (grupo com infecção crônica). Após seleção dos animais, os seis machos soronegativos foram inoculados com a cepa viral do vírus da artrite encefalite caprina (CAEV)-Co, título 10-5,6 TCID50/mL, por via intravenosa. A partir da inoculação viral este agrupamento passou a ser denominado de grupo com infecção recente e juntamente com o grupo com infecção crônica foram acompanhados, semanalmente por 180 dias, com análise dos testes de Western Blot (WB) no soro sanguíneo e plasma seminal. Nos animais com infecção crônica para LVPR, 18,94% (50/264) apresentaram anticorpos anti-LVPR em pelo menos uma das distintas amostras, e 81,06% (214/264) tiveram resultados negativos. Das amostras de soro sanguíneo do referido grupo, em 27,27% (36/132) detectou-se anticorpos anti-LVPR, enquanto que no plasma seminal 10,60% (14/132) foram reagentes no teste de WB. Nos animais inoculados com o CAEV-Co, ocorreu a soroconversão após a terceira semana da inoculação viral. Nesse grupo, 31,06% (41/132) das amostras de plasma seminal tiveram anticorpos anti-LVPR, sendo que dessas 41, 70,73% (29/41) coincidiram com resultado das amostras de soro sanguíneo. Nos 29,27% (12/41) restante, houve a detecção somente no plasma seminal e eram amostras provenientes de três animais (AIR2, AIR3 e AIR5). Em um dos animais com infecção recente, só foi identificado anticorpos anti-LVPR em amostras de plasma seminal, possivelmente em função da compartimentalização do vírus. Intermitência viral foi observada em ambas as amostras biológicas, independentemente do estágio de infecção. Conclui-se que a resposta imunológica em reprodutores com infecção recente LVPR é mais acentuada do que em animais cronicamente infectados. E, independentemente do estágio da infecção há uma flutuação nos níveis de anticorpos, sendo, portanto, um fator de risco, em virtude da existência de amostras falso-negativo ao realizar o diagnóstico.

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Serum samples (n = 1532) were collected between May 2011 to April 2012 from goats from 76 herds (49 from dairy farms and 27 herds for genetic improvement) from three geographical regions from the state of Pernambuco, Brazil: Zona da Mata, Agreste, and Sertão. Samples were processed using agar gel immunodiffusion test, with p28 CAEV antigen. The objective was to determine the risk factors for small ruminant lentivirus (SRLV) in dairy goats and goats with high genetic value. Overall, seroprevalence was 13.7% (210/1532) [95% CI: 12-15.4%] in animals and 67.1% (51/76) [95% CI: 56.5%- 77.7%] in herds. In dairy farms the seroprevalence was 73.5% (36/49) [95% CI: 61.1%- 85.8%], and in properties with animals of high genetic value it was 55.6% (15/27) [95% CI: 36.8%- 74.3%]. Robust Poisson regression analysis adjusted by the random effect of the herd showed that risk factors were: importing bucks from another Brazilian state (prevalence ratio [PR] = 4.73 [95% CI: 2.05; 10.88]), not isolating sick animals (PR = 3.27 [95% CI: 2.24; 4.76]), and participating in fairs/animal crowding (PR = 1.52 [95% CI: 1.09; 2.11]). Prevalence results show that SRLV is present in caprine herds in the state of Pernambuco and identified risk factors are strongly related to animal transit. Considering the epidemiological situation, the first step for mitigating the consequences of this disease would be controlling animal transit.

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Cross-species transmission events and mixed infection of small ruminant lentiviruses (SRLVs) were studied in seven goats and two sheep from three small ruminant mixed flocks from Northeast and Southeast Brazil. Genetic and antigenic analyses with gag/env genes and ELISA multiepitope SU1/SU5 recombinant antigens were carried out, respectively. The genetic analysis of gag and env sequences showed high viral diversity in both species, MVV-like (subtype A1) and CAEV-like B1 in goats, and CAEV-like (subtype B1) in sheep, revealing SRLV interspecies transmission from sheep to goats and vice versa in Brazilian farms. Two Brazilian caprine lentiviruses were segregated in two new genetic clades based on gag analyses, which suggests a new classification into heterogenic genotype A. Furthermore, goat isolates were grouped into subtype A1 and B1 clusters. Cross-reactive antibodies were detected in goats using ELISA with a recombinant antigen carrying SU1 and SU5 immunodominant epitopes; the results showed anti-CAEV and MVV antibodies in goats and anti-CAEV antibodies in sheep. This result can be associated with the high divergence in the V4 region due to SRLV variability. All results confirm cross-species infection of SRLV in Brazilian mixed herds.

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The complete gag gene from small ruminant lentiviruses (SRLV) encodes for a polyprotein of 55 kDa, known as p55gag. p55gag presents multiple antigenic epitopes, which can be recognized by antibodies, increasing the opportunity to detect SRLV-positive animals. Therefore, this polyprotein is considered an excellent candidate to use in diagnostic tests to detect antibodies against SRLV. Different studies have suggested that the selection of the recombinant antigen, which must be representative of the virus strains circulating in the test population, is crucial to avoid false negative results. Thus, the use of proteins from different viral strains isolated from goats or sheep of a given region or country may be a useful strategy to increase the ability to detect SRLV-infected animals. In the present study, the pMAL-p5X vector was used to express and purify p55gag (now called rp55gag for recombinant polyprotein 55 gag). The cloned gene was inserted downstream from the malE gene of Escherichia coli, which encodes a maltose-binding protein (MBP), resulting in the expression of an MBP fusion protein. The complete gag gene was amplified by RT-PCR. Finally, after digestion, the product was cloned into the pMAL-p5X vector and used to transform E. coli ER2325 cells. After the purification of MBP-rp55gag by affinity chromatography, the eluted fraction was observed by SDS-PAGE and Western Blot (WB). The WB was carried out with 85 serum samples from small ruminants previously analysed and compared by two commercial ELISAs. The results show that 76 of the serum samples were concordant with those by both ELISAs. Regarding the other nine serum samples, which showed discordant results between both ELISAs, were positive by WB. The results thus show that the rp55gag could be considered as an antigen in a confirmatory diagnostic assay to detect SRLV by WB. For this purpose, a future study with a high number of sera to determine the test specificity and sensitivity, using the p55gag of the circulating strain in Argentina will be necessary.

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Background: Small ruminant lentivirus (SRLV) belong to genus Lentivirus, family Retroviridae. These viruses causecaprine arthritis encephalitis (CAE) and maedi visna (MV), infectious diseases that cause economic, production, and reproductive losses. There are no effective treatments or vaccines for these diseases. Thus, early detection via serology hasgreat importance for control of SRLV. Therefore, the objective of this review is to demonstrate the potential of the westernblot (WB) test as an immunodiagnostic test for SRLV.Review: In general, immunodiagnosis of SRLV is performed via agar gel immunodiffusion (AGID) and indirect enzymelinked immunosorbent assay (ELISA), which can detect antibodies in several different biological samples but is used preferably with serum and blood plasma. However, WB has demonstrated efficacy in the early diagnosis of immunoglobulinsagainst SRLV, presenting higher sensitivity and specificity than the serological tests usually used, because this techniquecan detect antibodies at a dilution as much as 256 times greater than that of AGID and 32 times greater than that of ELISA.SRLV infection and consequent immunological activation result in the induction of cellular and humoral responses. Additionally, around the third week, production of antibodies directed mainly toward viral capsid proteins (p25 and p28)occurs. After the fifth week, production of immunoglobulins directed toward other viral proteins occurs. Because of thepersistence of SRLV infection, serology is considered to be the most practical means to diagnosis. Each serological testhas a percentage specificity and distinct sensitivity, as well as advantages and disadvantages in its applicability. It shouldbe noted that there is no gold standard test for diagnosis of SRLV infection. Moreover, SRLV are characterized by escapemechanisms such as genetic diversity, mutagenic potential, viral intermittence...(AU)

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Despite SRLV infection being endemic in Mexico, there is little information regarding which genotypes are present. We compared serotyping and PCR-sequencing results from sheep and goats infected with SRLV. We separated plasma and peripheral blood leukocytes (PBL) from 1940 blood samples from sheep and goats from 12 states across Mexico. To detect SRLV infection, we tested plasma samples using two commercial ELISA kits (VMRD and Eradikit SRLV Screening). Then, we serotyped the infecting virus (A/ B) using Eradikit SRLV Genotyping. PBL DNA was used to detect the proviral genome via PCR. Positive amplicons were sequenced to identify viral genotypes using a phylogenetic analysis. Also, we analysed for residues differences in the sequences of a capsid epitope between genotypes. The serological results indicated a higher detection of seropositive animals using the VMRD ELISA compared to Eradikit, with 21 % and 15.3 % more in sheep and goats respectively. Only 25.7 % of the ELISA serotyping results matched those from PCR-sequencing. PCR-sequencing was able to identify genotype A, B and coinfections in animals classified as indeterminate by the ELISA test. This lack of sensitivity may be related to the lack of epitopes from the matrix and transmembrane peptides used by ELISA screening. Sequences analysis revealed that SRLVs found in sheep cluster with genetic subtypes A2 and B1, while those in goats cluster with subtypes A1 and B1. Serotyping did not prove to be an adequate method for predicting the viral genotype (A and / or B) in infections caused by SRLV.

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Background: Small ruminant lentivirus (SRLV) belong to genus Lentivirus, family Retroviridae. These viruses causecaprine arthritis encephalitis (CAE) and maedi visna (MV), infectious diseases that cause economic, production, and reproductive losses. There are no effective treatments or vaccines for these diseases. Thus, early detection via serology hasgreat importance for control of SRLV. Therefore, the objective of this review is to demonstrate the potential of the westernblot (WB) test as an immunodiagnostic test for SRLV.Review: In general, immunodiagnosis of SRLV is performed via agar gel immunodiffusion (AGID) and indirect enzymelinked immunosorbent assay (ELISA), which can detect antibodies in several different biological samples but is used preferably with serum and blood plasma. However, WB has demonstrated efficacy in the early diagnosis of immunoglobulinsagainst SRLV, presenting higher sensitivity and specificity than the serological tests usually used, because this techniquecan detect antibodies at a dilution as much as 256 times greater than that of AGID and 32 times greater than that of ELISA.SRLV infection and consequent immunological activation result in the induction of cellular and humoral responses. Additionally, around the third week, production of antibodies directed mainly toward viral capsid proteins (p25 and p28)occurs. After the fifth week, production of immunoglobulins directed toward other viral proteins occurs. Because of thepersistence of SRLV infection, serology is considered to be the most practical means to diagnosis. Each serological testhas a percentage specificity and distinct sensitivity, as well as advantages and disadvantages in its applicability. It shouldbe noted that there is no gold standard test for diagnosis of SRLV infection. Moreover, SRLV are characterized by escapemechanisms such as genetic diversity, mutagenic potential, viral intermittence...

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This study aimed to evaluate by means of Nested Polymerase Chain Reaction (nPCR), co-cultivation and sequencing, with genetic comparison between strains (mother/newborn), the occurrence of vertical transmission of Small Ruminant Lentiviruses (SRLV) from naturally occurring nannies infected for their offspring. For the detection of SRLV seropositive progenitors, blood was collected from 42 nannies in the final third of gestation in tubes with and without anticoagulant. The diagnostic tests used were Western Blot (WB) and nPCR. During the period of birth, the same blood collection procedure was performed on 73 newborns at zero hours of birth, with the same diagnostic tests. Seventeen blood samples from seven-day-old kids, proven positive for SRLV by nPCR, chosen at random, were subjected to coculture in goat synovial membrane (GSM) cells for 105 days. The pro-viral DNA extracted from the cell supernatant from the coculture was subjected to nPCR. For DNA sequencing from the nPCR products, nine positive samples were chosen at random, four nannies with their respective offspring, also positive. Each sample was performed in triplicate, thus generating 27 nPCR products of which only 19 were suitable for analysis. Among the 42 pregnant goats, in 50% (21/42) pro-viral DNA was detected by nPCR, while in the WB, only 7.14% (3/42) presented antibodies against SRLV. Regarding neonates, of the 73 kids, 34 (46.57%) were positive for the virus, using the nPCR technique, while in the serological test (WB), three positive animals (4.10%) were observed. The coculture of the 17 samples with a positive result in the nPCR was confirmed in viral isolation by amplification of the SRLV pro-viral DNA. When aligned, the pro-viral DNA sequences (nannies and their respective offspring) presented homology in relation to the standard strain CAEV Co. It was concluded that the transmission of SRLV through intrauterine route was potentially the source of infection in the newborn goats.

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Caprine arthritis encephalitis (CAE) is a chronic disease caused by a retrovirus from the Lentivirus genus. No effective vaccines or treatments exist, and therefore genetic selection for CAE resistance might be a feasible alternative. To our best knowledge, no other studies have investigated the genetic architecture of CAE resistance in dairy goats. In this context, this study was designed to estimate genetic parameters for CAE infection in Alpine and Saanen goats using a Bayesian threshold model. A total of 542 adult goats (and >3-generation pedigree), which were group-housed in a population with high CAE prevalence, were tested based on a serological infection assessment test (negative = 1 or positive = 2) and used for this study. Genetic parameters were estimated using the BLUPF90 family programs. There was considerable genetic variability for CAE resistance, and pedigree-based heritability was significantly different from zero (0.026 < heritability < 0.128). Our findings indicate that the prevalence of CAE in goat herds can be reduced or eliminated through direct genetic selection for CAE resistance in addition to proper management strategies.

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Lentivirosis of small ruminants (LVPR) are chronic and degenerative infectious diseases, caused by Lentivirus, associated with numerous losses such as: drop in meat and milk production, predisposition to secondary infections, expenses with veterinary assistance and, even, early disposal of animals. In the northern region of Brazil, the epidemiological situation is poorly understood. Thus, this study aimed to determine the seropositivity of sheep for Lentivirus in Porto Acre city, Western Amazon, Brazil. 122 blood samples from sheep were collected and as a diagnostic method, agarose gel immunodiffusion was used, using the p28 protein of the capsid as antigen. The seropositivity of the sheep to the test was 8.2% (10/122). In 80% (4/5) of the investigated properties, the presence of seropositive animals was detected. It is worth noting that the acquisition of small ruminants from other states likely represented a risk to sheep health in the municipality of Porto Acre, Western Amazon, Brazil. It is concluded that there is a need for more systematic investigations on the prevalence of LVPR in the state of Acre.

As lentiviroses de pequenos ruminantes (LVPR) são enfermidades infecciosas crônicas e degenerativas, causadas por Lentivírus, associadas a inúmeros prejuízos como: queda na produção de carne e leite, predisposição a infecções secundárias, gastos com assistência veterinária e, até mesmo, descarte precoce dos animais. Na região norte do Brasil, a situação epidemiológica é pouco elucidada. Objetivou-se, assim, por meio deste estudo, determinar a soropositividade de ovinos para Lentivírus no município de Porto Acre, Amazônia Ocidental, Brasil. Foram coletadas 122 amostras de sangue de ovinos e como método diagnóstico foi empregada a imunodifusão em gel de agarose, utilizando a proteína p28 do capsídeo como antígeno. A soropositividade dos ovinos ao teste foi de 8,2% (10/122). Em 80% (4/5) das propriedades investigadas, detectou-se a presença de animais soropositivos. É válido ressaltar ainda que a aquisição de pequenos ruminantes advindos de outros estados provavelmente representou um risco à sanidade ovina no município de Porto Acre, Amazônia Ocidental, Brasil. Conclui-se que existe a necessidade de mais investigações sistemáticas sobre a prevalência de LVPR no estado do Acre.

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