True prevalence and spatial distribution of equine infectious anemia virus (EIAV) in horses from northeast region of Brazil

Equine infectious anemia (EIA) is a viral infection, caused by a lentivirus of the Retroviridae family, Orthoretrovirinael subfamily and its occurrence generates significant economic losses due to culling of positive animals as a measure of infection control. The objective of this work was to determine the prevalence of horses positive for equine infectious anemia virus (EIAV) and to identify the occurrence of areas with higher densities of cases in the states of Paraíba (PB), Pernambuco (PE), Rio Grande do Norte (RN) and Ceará (CE), Northeast region of Brazil, during the rainy (May and June) and dry (October and November) periods of 2017 and 2018. Serum samples from 6,566 horses from the states of PB, PE, RN and CE, Brazil, provided by the Laboratório Veterinária Diagnóstico - Ltda., were used. Serological diagnosis of EIA was performed using indirect enzyme-linked immunosorbent assay (ELISA) as a screening test and agar gel immunodiffusion test (AGID) as a confirmatory test. The apparent prevalence was obtained by dividing the number of seroreactive animals by the total number of animals, while the true prevalence was estimated by adjusting the apparent prevalence, considering the sensitivity (100%) and specificity (98.6%) of the diagnostic protocol used. For the construction of Kernel estimates, the Quartic function was used. In the dry season, of the 1,564 animals sampled, 28 were serologically positive, of which 19 belonged to the state of Ceará, 7 to Paraíba and 2 to Rio Grande do Norte. In 2018, it was observed that, during the rainy season, 26 of the 1,635 horses were seroreactive, with 19 cases resulting from Ceará, 4 from Paraíba and 3 from Pernambuco. In the dry season, 32 of the 1,526 animals were seroreactive to EIAV, of which 26 were from Ceará, 3 from Paraíba, 1 from Rio Grande do Norte and 2 from Pernambuco. In the dry period of 2017, the CE had a real prevalence of 1.22% (95% CI = 0.05 - 2.99%). In 2018, during the rainy season, prevalences of 0.03% (95% CI = 0 - 1.18%) were identified in CE and 1.69% (95% CI = 0 - 8.38%) in PE. Regarding the 2018 dry period, a prevalence of 1.32% (95% CI = 0.26 - 2.84%) was found in the state of CE. In both dry and rainy periods of 2017, the presence of spatial clusters of animals positive for EIA was observed, mainly in the border areas among the states of CE, PE, PB and RN. In 2018, there was a variation in the distribution of areas with higher densities of cases between the rainy and dry periods. The state of CE had the highest prevalence of positive animals and the presence of areas with higher densities of EIA cases in both climatic periods, in the years 2017 and 2018. In some municipalities of the CE, important sporting events of agglomeration of animals take place, which can favor the transmission of EIAV by facilitating the contact of infected and susceptible animals. Population density may be a factor associated with the higher prevalence observed in this region, as it has the second largest herd among the states studied. Higher densities indirectly contribute to the occurrence of infectious diseases, as they favor the contact of infected and susceptible animals. The occurrence of higher densities of cases in the border areas of the states of PE, RN, CE, and PB may be related to the greater movement of animals in these regions, favoring the indirect contact of infected horses with susceptible ones. The observed results demonstrate the circulation of the EIAV in four states in the Northeast region of Brazil.(AU)

Equine infectious anemia on Marajo Island at the mouth of the Amazon river / Anemia infecciosa equina na Ilha de Marajó na foz do Rio Amazonas

Equine infectious anemia (EIA) is a transmissible and incurable disease caused by a lentivirus, the equine infectious anemia virus (EIAV). There are no reports in the literature of this infection in Equidae on Marajo Island. The objective of this study was to diagnose the disease in the municipalities of Cachoeira do Arari, Salvaterra, Santa Cruz do Arari and Soure, on Marajó Island, state of Pará, Brazil. For serological survey samples were collected from 294 horses, over 5-month-old, males and females of puruca and marajoara breeds and from some half-breeds, which were tested by immunodiffusion in Agar gel (AGID). A prevalence of 46.26% (136/294) positive cases was found. EIA is considered endemic in the municipalities studied, due to the ecology of the region with a high numbered population of bloodsucking insect vectors and the absence of official measures for the control of the disease...

A anemia infecciosa equina (EIA) é uma importante enfermidade, transmissível e incurável causada por um lentivírus, equine infectious anemia vírus (EIAV), e não há relatos na literatura desta infecção em equinos da Ilha de Marajó. O objetivo deste estudo foi diagnosticar a anemia infecciosa equina nos municípios de Cachoeira do Arari, Salvaterra, Santa Cruz do Arari e Soure, Ilha de Marajó, no bioma amazônico do estado do Pará, Brasil. Para a pesquisa sorológica foram coletadas 294 amostras de animais da espécie equina, acima de cinco meses de idade, de ambos os sexos, das raças puruca, marajoara e de mestiços, testadas pela imunodifusão em gel de Agar (IDGA). Foi verificada uma prevalência de 46.26% (136/294) de casos positivos para EIA. A doença é considerada endêmica nos municípios estudados, tanto pelos aspectos ecológicos da região que propiciam a manutenção da população de insetos hematófagos vetores, quanto pela ausência de medidas oficiais de controle da doença...

Seroprevalencia de anemia infecciosa equina en los departamentos de Córdoba y Bolívar, Colombia / Seroprevalence of Equine Infectious Anemia in the Departaments of Córdoba and Bolivar, Colombia

La anemia infecciosa equina (AIE) es una enfermedad causada por un virus ARN de la familia Retroviridae, subfamilia Lentiviridae que afecta a todos los miembros de la familia de los équidos y posee distribución mundial. El objetivo del presente estudio fue estimar la seroprevalencia del virus de la anemia infecciosa equina (VAIE) en los departamentos de Córdoba y Bolívar, Colombia. Se realizó un estudio prospectivo que incluyó 380 équidos escogidos de forma aleatoria procedente de seis municipios de Córdoba (Montería, Puerto Escondido, Los Córdoba, Canalete, Sahagún y San Antero) y cinco municipios de Bolívar (El Carmen de Bolívar, Mompox, María la Baja, Magangue y Turbaco). Tres especies fueron incluidas: equinos (n=305), asnal (n=46) y mular (n=29), pertenecientes a 42 predios en los dos departamentos. El presente estudio permitió establecer una seroprevalencia al VAIE de 9,7% (37/380) en el total de équidos analizados, siendo para el departamento de Córdoba de 7,73% (15/194) en cuanto a los animales y de 53,8% (7/13) en predios y para el departamento Bolívar fue de 11,8% (22/186) en los animales y en predios de 34,48% (10/29). El presente estudio permitió conocer la seroprevalencia del VAIE en los departamentos de Córdoba y Bolívar y algunos datos demográficos relacionados con la enfermedad en estas regiones del país.

The Equine Infectious Anemia (EIA) is a disease caused by an RNA virus of the family Retroviridae, subfamily Lentiviridae, that affects all members of the Equidae family with a worldwide distribution. The main goal of this study was to estimate the seroprevalence of the Equine Infectious Anemia Virus (EIAV) in the Departments of Bolívar and Córdoba, Colombia. A prospective study was carried out and included 380 equidae from six municipalities of Córdoba (Montería, Puerto Escondido, Los Córdobas, Canalete, Sahagún, and San Antero) and five municipalities of Bolívar (El Carmen de Bolívar, Mompox, María La Baja, Magangue, and Turbaco). The animals were randomly selected and three species were included, namely donkeys (n=46), mules (n=29), and horses (n=305) from 42 farms in the two departments studied. The results enabled to establish a EIAV seroprevalence of 9.7% (37/380) in the total number of equidae analyzed in the Departments of Córdoba and Bolívar. The seroprevalence distribution was as follows: for the Department of Córdoba, 7.73 % (15/194) in terms of animals and 53.8 % (7/13) for the farms. For the Department of Bolívar, 11.8 % (22/186) in animals and 34.48 % (10/29) for the farms. These results also allowed to know some demographic data related to this disease in these regions.

The efficacy of ELISA commercial kits for the screening of equine infectious anemia virus infection / Eficacia de ensayos de ELISA comerciales para el screening de infección por el virus de la anemia infecciosa equina

The most used and reliable indicator of equine infectious anemia virus (EIAV) infection is the detection of its specific antibodies in horse serum. In the present study, the performance of two commercial ELISA tests for the detection of EIAV antibodies as well as the potential advantages of their use as an EIAV infection screening tool were evaluated in 302 horse serum samples. Both ELISA assays showed 100% diagnostic sensitivity, and 92.3-94.3% diagnostic specificity. Discordant results were analyzed by immunoblot. The results showed that both ELISA tests are very efficient at detecting EIAV infected animals, allowing to identify a higher number of positive horse cases. Thus, ELISA assays can be useful tools in EIA control and eradication.

El mejor indicador de la infección por el virus de la anemia infecciosa equina (Equine infectious anemia virus, EIAV) es la detección de anticuerpos específicos en el suero del caballo. En el presente trabajo se evaluó la capacidad de detección de anticuerpos contra EIAV de dos equipos de ELISA comerciales utilizando 302 muestras de suero equino, así como las ventajas potenciales de su uso como herramientas de screening. Ambos ensayos de ELISA presentaron 100 % de sensibilidad diagnóstica y una especificidad diagnóstica del orden de 92,3 a 94,3 %. Las muestras discordantes fueron analizadas por inmunoblot. Los resultados mostraron que las dos pruebas ELISA son muy eficientes para detectar animales infectados por EIAV, al permitir identificar un mayor número de animales positivos que la prueba de inmunodifusión en gel de agar, oficialmente aprobada en la República Argentina para la certificación de los animales. Las pruebas de ELISA constituyen herramientas muy útiles en los programas de control y de erradicación de la infección por EIAV.

The Comparison of Genetic Variation in the Envelope Protein Between Various Immunodeficiency Viruses and Equine Infectious Anemia Virus / 中国病毒学·英文版

The envelope protein(Env) of lentiviruses such as HIV,SIV,FIV and EIAV is larger than that of other retroviruses.The Chinese EIAV attenuated vaccine is based on Env and has helped to successfully control this virus,demonstrating that envelope is crucial for vaccine.We compared Env variation of the four kinds of lentiviruses.Phylogenetic analysis showed that the evolutionary relationship of Env between HIV and SIV was the closest and they appeared to descend from a common ancestor,and the relationship of HIV and EIAV was the furthest.EIAV had the shortest Env length and the least number of potential N-linked glycosylation sites(PNGS) as well as glycosylation density compared to various immunodeficiency viruses.However,HIV had the longest Env length and the most PNGS.Moreover,the alignment of HIV and SIV showed that PNGS were primarily distributed within extracellular membrane protein gp120 rather than transmembrane gp41.It implies that the size difference among these viruses is associated with a lentivirus specific function and also the diversity of env.There are low levels of modification of glycosylation sites of Env and selection of optimal protective epitopes might be useful for development of an effective vaccine against HIV/AIDS.

Patología ultraestructural del músculo gluteus medius de caballos criollos en los llanos venezolanos infectados naturalmente por el virus de la anemia infecciosa equina / Structural pathology of gluteus medius from creole horses of venezuelan plains naturally infected by equine infectious anemia virus

La Anemia Infecciosa Equina (AIE) es una enfermedad viral, de curso agudo a crónico, que afecta a los équidos en general en los llanos venezolanos. Hasta el momento, no se han analizado los posibles efectos que pueda tener la AIE sobre el músculo esquelético. En la presente investigación se realizó un estudio ultraestructural de las fibras musculares del músculo Gluteus medius, de caballos seropositivos al test de Coggins, teniendo animales seronegativos al citado test como controles de campo. Las biopsias musculares se procesaron por las técnicas convencionales de corte fino para la microscopía electrónica de transmisión. El análisis de las micrografías electrónicas de animales seropositivos mostró cambios subletales y letales. Como alteraciones subletales, se observaron en el sistema contráctil, atrofia y trazo irregular de la línea Z. En el sistema sarcotubular se evidenció edema de las cisternas terminales. Las mitocondrias exhibieron una matriz con diferentes densidades electrónicas y la presencia de gránulos electrón densos. Se observaron variadas estructuras lisosomales. Por su parte, las alteraciones letales se distinguieron por diferentes grados de hipercontracción, pérdida total de la organización de los sistemas contráctil y sarcotubular, degeneración de las mitocondrias, ruptura del sarcolema y necrosis segmental. Los capilares intramusculares exhibieron alteraciones como el engrosamiento y reduplicación de la membrana basal, prolongaciones del citoplasma endotelial hacia la luz y pérdida de la continuidad de la pared endotelial. Se evidenciaron también pericitos, unos aparentemente normales, otros con alteraciones. El infiltrado celular consistió en macrófagos y neutrófilos. Los presentes hallazgos permiten sugerir que los mismos se corresponden con lo reportado por otros autores en relación a los efectos de las enfermedades autoinmunes sobre la ultraestructura del músculo esquelético.

The equine infectious anemia (EIA) is a viral disease of acute response and progress to chronic course which affects equine of Venezuelan plains. Until now, there is no information about the possible effect of EIA on skeletal muscle ultrastructure. The aim of the present investigation was to study the ultrastructure of muscle Gluteus medius from horses positive to Coggins test and animal control negative to the test. Muscle biopsies were processed by routine techniques for transmission electron microscopy. Muscle alterations varied from slight to severe, including atrophy, swelling of sarcotubular system and mitochondria. Mitochondria showed a matrix with different electron densities and the presence of electron dense granules. There were observed different kinds of lysosomes. More severe alterations included hypercontraction and complete loss of myofilaments, rupture of sarcolemma and segmental necrosis. Intramuscular capillaries exhibited endothelial cell cytoplasm infoldings into the lumen and partially or totally occluded lumen. Basement membrane was widened and reduplicated. Some capillaries showed widened endothelial cell cytoplasm, mitochondria and rough endoplasmic reticulum swelling and even degenerated. Others showed ruptured endothelial wall. Pericytes exhibited a cytoplasm which varied from normal to a proliferative one. The mononuclear cell infiltrate consisted of macrophages and neutrophils. Most of observed alterations have been described in muscle disorders with an autoimmune component.

Proviral Genomic Variation of EIAV Envelop gp 90 Gene Observed in Experimentally Infected Horse / 中国兽医学报

The present experiment was designed to observe the genetic variation of equine infectious anemia virus (EIAV) envelop gp 90 gene in infected horse. One horse was infected experimentally with P337-V70 strain and showed no clinical signs after being infected at twice with the same virus strain. Seventeen proviral sequences covering principal neutralizing domain (PND) of EIAV gp 90 gene were obtained from the buffy coat and liver of the horse through PCR amplification and cloning. Comparative analysis of the sequences revealed that some sequences contained the nucleotide insertions in the PND region. The insertions might be generated by direct repeat and strand displacement of sequence segment in their PND gene, showing different lenghts.