Neospora caninum tachyzoites inoculated by the conjunctival route are not vertically transmitted in pregnant cattle: a descriptive study.

The aim of this study was to evaluate whether Neospora caninum tachyzoites (Nc-1) inoculated by the conjunctival route in pregnant cows were able to generate infection in their fetuses. Group 1 contained 2 naturally infected cows; group 2 contained two cows inoculated intravenously with 2.5 × 10(8) tachyzoites, group 3 contained two cows inoculated with 2.5 × 10(8) tachyzoites by the conjunctival route, and group 4 contained two uninfected control cows. The four inoculated cows from groups 2 and 3 were challenged at 23 weeks of gestation. An indirect fluorescent antibody test (IFAT), recombinant NcGRA7-based ELISA, ELISA for IgG subisotypes and Western blot analysis were assessed to characterize the humoral immune response in dams. Sera from their fetuses were tested also using Western blot analysis. Routine microscopic evaluation of H&E stained fetal tissues was made and any fetal tissues and placentas with lesions compatible with Neospora-infection were processed by immunohistochemistry (IHC). DNA extraction from fresh and formalin-fixed, paraffin-embedded fetal tissues were tested by nested PCR. All dams from groups 1, 2 and 3 were seropositive by IFAT, rNcGRA7-based-ELISA and Western blot. IgG1/IgG2 ratios were ≤ 1 at weeks 27 and 29 of gestation. Only fetuses from groups 1 and 2 developed N. caninum specific antibodies by Western blot. Histopathological lesions compatible with those caused by N. caninum were observed in fetuses from groups 1 and 2. N. caninum cysts and tachyzoites were observed by IHC on fetal tissues from groups 1 and 2. Only fetal samples from group 2 were positive by PCR. Further work is needed not only to characterize the cellular immune response but also to clarify the consequences on the dam after conjunctival inoculation of N. caninum tachyzoites. This study shows that N. caninum tachyzoites inoculated by the conjunctival route were not vertically transmitted in pregnant cows.

Retrospective study of bovine neonatal mortality: cases reported from INTA Balcarce, Argentina / Estudio retrospectivo de mortalidad neonatal bovina: Casos hallados en INTA-Balcarce, Argentina

A retrospective study was performed on 169 beef and dairy calves aged from 1 to 7 days old submitted to the Diagnostic Laboratories at INTA Balcarce, Argentina. Bacterial culture was performed for aerobic and microaerophilic organisms. Samples from spleen and lymph nodes, and peripheral blood mononuclear cells were also cultured for viral isolation on cell culture. Bovine rotavirus was detected by direct-ELISA. Multiple tissue samples were fixed in 10% formalin, routinely processed and stained with hematoxylin and eosin for microscopic examination. Etiological diagnosis was made in 70 of the 169 calves. Infectious agents were identified in 49 cases, the most common being Escherichia coli. When the histopathological examination was performed in cases with undetermined diagnosis, it was noted that 44 specimens had histological lesions, which suggested the presence of an infectious agent. In order to characterize the causes of bovine neonatal mortality, the protocols and methodology should be improved in further works.

Se realizó un estudio restrospectivo en 169 terneros muertos 1 a 7 días después del nacimiento pertenecientes a rodeos para carne y leche, remitidos a los Laboratorios de Diagnóstico del INTA Balcarce, Argentina. Para detectar organismos aeróbicos y microaerófilos se realizó el cultivo bacteriano. Para el aislamiento viral sobre cultivo celular, se recolectaron muestras de bazo, ganglios linfáticos y sangre periférica. El rotavirus bovino fue identificado por ELISA directo. Se efectuó el examen microscópico de diferentes tejidos, los cuales fueron fijados en formol al 10%, procesados y teñidos con hematoxilina y eosina. Se obtuvo un diagnóstico etiológico en 70 de los 169 terneros. Se identificaron agentes infecciosos en 49 casos, siendo el más común Escherichia coli. En los casos con diagnóstico indeterminado, el examen histopatológico realizado determinó que 44 especímenes poseían lesiones compatibles con la presencia de agentes infecciosos. Es necesario mejorar los protocolos y las metodologías de trabajo a los fines de caracterizar las causas de mortalidad neonatal en bovinos.

Neosporosis bovina: conceptos generales, inmunidad y perspectivas para la vacunación / Bovine neosporosis: general concepts, immunity and perspectives for vaccination

Neospora caninum es agente causal de aborto en bovinos de regiones ganaderas de todo el mundo. Su ciclo de vida es heteroxeno siendo el perro (Canis familiaris) y el coyote (Canis latrans) los hospedadores definitivos reconocidos hasta el presente. La infección transplacentaria es un eficiente mecanismo de transmisión de la enfermedad pero existe evidencia que demuestra la transmisión postnatal en los bovinos. Debido a las pérdidas económicas que causa la neosporosis, diversas técnicas diagnósticas han sido desarrolladas. La fisiopatología del aborto causado por N. caninum no ha sido completamente esclarecida. La modulación del sistema inmune por efecto de la preñez ocasiona un período de susceptibilidad al aborto por N. caninum. Aunque la resistencia al parásito ha sido asociada con una respuesta de linfocitos T tipo 1, dicha respuesta inmune es incompatible con una preñez exitosa. Sin embargo, los mecanismos inmunes presentes en animales crónicamente infectados protegen del aborto ante una segunda exposición al protozoo. La comprensión de esa respuesta inmune adquirida constituye un desafío para el desarrollo de inmunógenos. Este trabajo menciona conceptos generales de la neosporosis bovina haciendo énfasis en los mecanismos inmunes y las perspectivas para la vacunación.

Neospora caninum causes abortions in cattle worldwide. The Neospora-cycle of life is heteroxenous. Dogs (Canis familiaris) and coyotes (Canis latrans) are the definitive hosts known at present. Although, transplacental infection is an efficiently mode of transmission in cattle; there are also experimental and field data that prove horizontal transmission. Several techniques are available for diagnosis since neosporosis is recognized as a disease that causes economic losses in cattle. The mechanisms that produce the abortion are not completely understood. The immunomodulation observed during the pregnancy, is associated with a susceptible period where Neospora-abortion can occur. Resistance to the parasite is dependent on T helper cell 1 cytokine responses. This has important repercussions for pregnant female bovine because strong T helper cell 1 cytokine responses are incompatible with successful pregnancy. However, it was demonstrated that chronically infected cows develop immune mechanisms against the abortion caused by a second Neospora-exposure. The comprehension of those mechanisms is needed for the formulation of Neospora-vaccines that prevent bovine neosporosis. General concepts about neosporosis with emphasis in the immune response and perspectives for vaccination are mentioned in the present review.

Análisis retrospectivo de casos con diagnóstico de necrosis cerebrocortical y su relación con herpesvirus bovino tipo 5 / Retrospective study of archive cases of cerebrocortical necrosis and their relationship with bovine herpesvirus type 5

A los fines de establecer la asociación entre herpesvirus bovino tipo 5 (HVB-5) y la necrosis cerebrocortical (NCC) se analizaron 89 casos bovinos de tres regiones de Buenos Aires registrados entre 1970-1999. El tejido nervioso fue teñido con hematoxilina-eosina o hibridización in situ para cADN-BHV-5. Las lesiones se clasificaron en una escala subjetiva de 0-3. La mayor prevalencia fue entre 1979-1984, principalmente en primavera, no existiendo diferencias (P>0,05) en las tasas de morbilidad y mortalidad entre grupos etarios, sexo, raza, sistemas de producción y regiones. Amaurosis (48 por ciento), ptialismo (42 por ciento), torneo (40 por ciento), ataxia (36 por ciento) y bruxismo (37 por ciento) fueron los síntomas más observados. Las lesiones estuvieron distribuidas en corteza anterior y posterior (90,6 por ciento) y diencéfalo (36,5 por ciento). Meningitis y manguitos perivasculares (94,4 por ciento) y gliosis difusa (77,5 por ciento) o focal (73 por ciento) fueron los hallazgos predominantes en el cerebro. Se observaron focos de necrosis en el 66,6 porciento de los casos. HVB-5 fue aislado en 9/19 casos a partir de 1992 y cADN-HVB-5 fue detectado en 3/9 casos. La identificación viral en casos con lesiones severas resultó negativa. La correspondencia de NCC con aislamiento viral de bovinos con similares características clínico-epidemiológicas permiten concluir la asociación del HVB-5 y lesiones de NCC.

Humoral immune response to infectious agents in aborted bovine fetuses in Argentina

The purpose of this study was to characterize the exposure of bovine aborted fetuses from beef and dairy herds of the humid pampas of Argentina to different infectious agents by the evaluation of fetal fluid antibodies. Presence of fetal antibodies to bovine viral diarrhea virus genotype 1 (BVDV-1), bovine herpes virus type 1 (BHV-1), Leptospira interrogans, Brucella abortus, and Neospora caninum was determined. Of the 95 fetuses processed, 66 came from 49 beef herds and 29 from 12 dairy herds. The average gestational age of the aborted fetuses was 7.1 months. Antibodies to the mentioned agents were detected in 65 of the 95 fetal fluids (68.4

). In addition, antibodies to more than one infectious agent were detected in 32 fetuses (33.7

), suggesting fetal exposure to multiple antigens during gestation. There were antibodies to BVDV-1, BHV-1, N. caninum and Leptospira interrogans in 43 (45.2

) and 5 (5.2

) specimens, respectively. Antibodies to B. abortus were not detected in any of the fetal fluids. The results of this study provide information on the determination of antibodies in fluids from bovine aborted fetuses exposed to different infectious agents in the region.

Experimental toxicity of verbesina encelioides in sheep and isolation of galegine.

Verbesina encelioides is a widely distributed weed in Argentina. Although it has been suspected as poisonous, there seem to be no previous reports of its toxicity in this country. Its biological activity was evaluated through an experiment in sheep. Four 5-y-old sheep, averaging 33 kg in body weight, were given a single dose of 1.0, 3.2, 5.0 or 6.3 g of dried plant material (17.9% dry matter)/kg body weight orally in a water suspension. Forty-eight hours later, the animals given 5.0 g or 6.3 g showed dullness and lack of appetite. The higher dosed sheep became recumbent a few hours later and died 60 h after dosing without showing further signs. The other animals showed no signs. Necropsy of the dead sheep showed severe lesions in different organs: liver, kidneys, lungs, lymph nodes and digestive tract. Hydrothorax was also observed. The animal receiving 5.0 g/kg was sacrificed after 72 h to determine the degree of recovery or lesions. Microscopically, severe glomerulonephrosis and congestion in the liver, with cellular degeneration and fatty changes were observed. Additionally, hemorrhagic lymph nodes, and hemorrhagic and edematous lungs were noted. No gross nor microscopic lesions were found in the sheep receiving 5.0 g/kg. Mice injected ip with the chromatographic extract died in less than 15 min. Galegine was identified in the plant material. The minimum toxic dose of 5-6 g/kg indicates a high toxicity when compared to other poisonous plants of the southeastern area of Buenos Aires province, Argentina.

A case of solanum malacoxylon toxicity in pigs.

The postmortem and histological changes seen in the kidneys, lungs and vascular system in spontaneous Solanum malacoxylon poisoning on a pig farm in Buenos Aires Province, Argentina, are reported. Macroscopic calcified plaques in the endocardium, aorta, and pulmonary artery and mineralization in renal pelvis were observed. Microscopic examinations revealed tubulonephrosis and calcification of the elastic fibers of kidney vessels. Severe calcinosis of the endocardium and elastic fibers of arteries (aorta, pulmonary, renal) were seen. In the lung, calcification of the elastic fibers of the alveolar wall and the lamina propia of the bronchia were also noted.

Immunopathology of experimental Brucella abortus strain 19 infection of the genitalia of bulls.

Antibody responses in serum and semen, and immunoglobulin containing cell (ICC) populations in the genitalia of bulls were compared after inoculating Brucella abortus strain 19 into the seminal vesicles of two bulls (ISV route) and into testes in two other bulls (IT route). Bulls seroconverted as early as 1 week post-infection (PI). Peak serum titres as determined by the serum agglutination test (SAT), complement fixation test (CFT) and ELISA occurred at PI weeks 3, 4 and 5 respectively. Highest titres were in IT inoculated bulls. Seminal antibodies against B. arbotus S19 were demonstrated from 2 weeks PI by both the SAT and the Rose Bengal Test (RBT) and highest titres occurred at PI weeks 3 and 4. Examination of immunoglobulins (Ig) in semen, however, revealed no significant differences of Ig isotypes between infected and control animals at any examination time. When bulls were killed at 7 weeks PI, quantitation of ICC in genital sections stained by the peroxidase-anti-peroxidase method revealed an overwhelming predominance of IgG containing cells in inflamed organs. In all cases IgG1- and IgG2-containing cells were prevalent, and present in approximately equal numbers. IgA-containing cells were second in prevalence in inflamed tissues while IgM cells were always in low percentage. High prevalence of ICC in infected genitalia, associated with elevated specific seminal antibodies but not with increased seminal Ig indicates that most Ig remains localised in tissues and is not transferred into genital secretions.

Lesions of presumed congenital origin in the accessory sex glands of bulls.

A detailed description of lesions of presumed congenital origin involving the accessory sex glands of 11 bulls is given. All of these lesions would have been detectable by careful clinical examination during bull evaluation. Evidence presented here supports the view that congenital abnormalities such as bilateral ampulla-seminal vesicle fusion, ampulla cysts associated with luminal constriction, cysts of urogenital sinus origin, prostatic appendage, and persistent remnant of the urachus could sometimes be responsible for development of inflammatory conditions in the accessory sex glands. Anomalies such as segmental aplasia or hypoplasia of mesonephric duct derivations, or single ampulla-seminal vesicle fusion in which the ducts opened freely in the colliculus seminalis were not seen to be associated with inflammation in the accessory sex glands. The significance of these findings is considered.

Pathological findings in the bulbourethral glands of bulls.

The bulbourethral glands of 323 Bos indicus or B. indicus crossbred bulls more than 1 1/2 years old were examined in an abattoir study. Bulbourethral adenitis was diagnosed grossly and confirmed by histological examination in 4 (1.2%). Unilateral chronic interstitial inflammation was seen in 2 cases; one of these was associated with a degenerative-type seminal vesiculitis. In the others adenitis was bilateral; in one case it was associated with a concretion and foreign (plant) material in the principal duct of the left bulbourethral gland; in the other bilateral case, numerous calculi were present and microscopically, a chronic active and diffuse inflammation was observed. Chemical analysis of the calculi showed calcium oxalate and tricalcium phosphate to be the most important components. Corynebacterium spp was isolated from the lesion with multiple calculi but attempts to isolate Chlamydia spp, Mycoplasma spp and Brucella abortus from the 4 adenitis cases were unsuccessful. Congenital abnormalities such as glandular fusion (2.2%) or unilateral aplasia (0.6%) were also observed. Cysts were the most common finding (19.2%), and duct dilation was frequent (7.1%). The significance of these findings in relation to fertility is considered.