Cattle rabies: the effect of clinical evolution, viral genetic lineage, and viral load on the severity of histological lesions / Raiva bovina: relação do curso clínico, da linhagem genética do vírus e carga viral com a intensidade de lesões histológicas

Our objective was the characterization and staging of histological lesions in different anatomical sites of the central nervous system (CNS) of rabid cattle. The severity of the lesions was compared with the clinical stages of the disease, the variants of viral isolates, and with the load of virus. Thirty-one spontaneously affected rabid cattle the state of Santa Catarina underwent clinical follow-up and were eventually necropsied. CNS tissues were sampled and submitted to direct fluorescent antibody technique (DFAT), immunohistochemistry (IHC), routine histopathology with hematoxylin and eosin stain (HE), reverse transcriptase polymerase chain reaction (RT-PCR), and polymerase chain reaction in quantitative reverse transcriptase in real time (qRT-PCR). Affected cattle were allotted in four groups according to their clinical stage when euthanized: G1, euthanized while standing; G2, euthanized when in sternal recumbence; G3, euthanized when in lateral recumbence; and G4, affected cattle with natural death. In order to evaluate the degree of severity of the lesions and the presence of Negri bodies (NBs), the brain was sectioned at 9 sites. Additionally, spinal cord and trigeminal ganglion sections were examined. The intensity of the lesions was graded as either absent, mild, moderate, or marked, and the presence or absence of the NBs was noted. Histological lesions were characterized by lymphocytic and monocytic meningoencephalitis with NBs in 28 cases. In all analyzed groups, intensities of histological lesions ranging from mild to severe were observed. Brain regions with the highest inflammatory lesion intensity were the medulla at the level of obex, followed by the colliculus and thalamus. NBs were observed in a higher percentage in the cerebellum, followed by medulla at the obex level, striatum complex, and frontal telencephalon. The duration of the clinical course of the disease did not influence the intensity of the inflammatory lesion, but it did influence the presence of NBs, with a higher percentage of these inclusions in cattle that died naturally than in euthanized cattle. All isolated rhabdovirus included in this study were genetically compatible with samples from hematophagous bats Desmodus rotundus. The evaluation by qRT-PCR did not demonstrate a correlation between lesion intensity and the amount of virus.(AU)

Nosso objetivo foi a caracterização e estadiamento de lesões histológicas em diferentes locais anatômicos do sistema nervoso central (SNC) de bovinos raivosos. A gravidade das lesões foi comparada com os estágios clínicos da doença, as variantes dos isolados virais e com a quantidade de vírus. Trinta e um bovinos do estado de Santa Catarina, afetados naturalmente por raiva, foram acompanhados clinicalmente e, ao final, necropsiados. Os tecidos do SNC foram amostrados e submetidos a imunofluorescência direta, imunohistoquímica, histopatologia de rotina, reação em cadeia da polimerase via transcriptase reversa (RT-PCR) e reação em cadeia da polimerase em transcriptase reversa quantitativa em tempo real (qRT-PCR). Os bovinos afetados foram distribuídos em quatro grupos, de acordo com sua fase clínica: G1, eutanasiados quando ainda se mantinham em pé; G2, eutanasiados quando em decúbito esternal; G3, eutanasiados quando em decúbito lateral; e G4, bovinos afetados com morte natural. Para avaliar o grau de gravidade das lesões e a presença de corpúsculos de Negri (CNs), o cérebro foi seccionado em 9 locais. Além disso, seções da medula espinhal e do gânglio trigêmeo foram examinadas. A intensidade das lesões foi graduada como ausente, leve, moderada ou acentuada, e a presença ou ausência dos CNs foi anotada. Lesões histológicas foram caracterizadas por meningoencefalite linfocítica e monocítica com CNs em 28 casos. Em todos os grupos analisados foram observadas intensidades de lesões histológicas variando de leve a grave. As regiões cerebrais com maior intensidade de lesão inflamatória foram o bulbo no nível do obex, seguido do colículo e tálamo. CNs foram mais prevalentes no cerebelo, seguido pelo bulbo ao nível do óbex, corpo estriado e telencéfalo frontal. A duração do curso clínico da raiva não influenciou a intensidade da lesão inflamatória, mas influenciou a presença de CNs, com maior porcentagem dessas inclusões em bovinos que morreram naturalmente do que em bovinos sacrificados. Todos os isolados rabdovírus obtidos neste estudo eram geneticamente compatíveis com amostras provenientes de morcegos hematófagos Desmodus rotundus.(AU)

Inclusion Bodies are Formed in SFTSV-infected Human Macrophages / 病毒学报

The severe fever with thrombocytopenia syndrome virus (SFTSV) is a new member in the genus Phlebovirus of the family Bunyaviridae identified in China. The SFTSV is also the causative pathogen of an emerging infectious disease: severe fever with thrombocytopenia syndrome. Using immunofluorescent staining and confocal microscopy, the intracellular distribution of nucleocapsid protein (NP) in SFTSV-infected THP-1 cells was investigated with serial doses of SFTSV at different times after infection. Transmission electron microscopy was used to observe the ultrafine intracellular structure of SFTSV-infected THP-1 cells at different times after infection. SFTSV NP could form intracellular inclusion bodies in infected THP-1 cells. The association between NP-formed inclusion bodies and virus production was analyzed: the size of the inclusion body formed 3 days after infection was correlated with the viral load in supernatants collected 7 days after infection. These findings suggest that the inclusion bodies formed in SFTSV-infected THP-1 cells could be where the SFTSV uses host-cell proteins and intracellular organelles to produce new viral particles.

Characterization of fibrillous inclusion body (FIB) of human adenovirus type 41 (Ad41) using immunoelectron microscopy / 病毒学报

To investigate the components of fibrillous inclusion body (FIB), which was formed in packaging cells during the replication of human adenovirus type 41 (Ad41), Ad41 long fiber knob (LFK) and short fiber knob (SFK) proteins were expressed in prokaryote respectively and then used to immunize BALI mice for preparation of anti-LFK serum and anti-SFK sera. The activity and specificity of anti-LFK and an ti-SFK sera were confirmed with Western blot, indirect immunofluorescence assay (IFA) and immunonegative staining, suggesting these sera could be applied in immuno-colloidal gold labelling electron microscopy (EM). 293TE cells were infected with wild-type Ad41. Ultrathin sections of infected cells were made, and labelled with immuno-colloidal gold technique using anti-Ad41 sera, anti-LFK sera, anti-SFK sera, or anti-fiber monoclonal antibody 4D2, respectively. The labelled sections were observed under EM, and the results demonstrated that both Ad41 long fiber protein and short fiber protein were included FIB.

A case report of herpetic and candidal esophagitis in an immunocompetent adult

Reports of combined candidal and herpetic esophagitis in immunocompetent states are rare and sporadic. A 44-year-old previously healthy lady presented with a one week history of progressive dysphagia, odynophagia and fever. Esophagogastroduodenoscopy (EGD) showed extensive desquamation of the entire esophagus except for distal 4 cm. Histopathological examination revealed ulcerated and inflamed squamous epithelium with the margin of ulcer showing a few overhanging squamous cells with dense eosinophilic cytoplasm, multinucleated and faceted nuclei with glassy chromatin, and an occasional Cowdry type A intranuclear inclusion bodies. Few candidal spores were seen in the underlying stroma. Intravenous acyclovir, fluconazole and pantoprazole were initiated. Oral analgesics were given for pain relief. She was treated for a total of 14 days. She showed significant improvement and was tolerating oral intake after discharge. The patient was asymptomatic with no evidence of recurrence at a 2-month follow-up.

Distribuição do vírus rábico no sistema nervoso central em ruminantes naturalmente infectados / Distribution of rabies vírus in the central nervous system in naturally infected ruminants

Com o objetivo de identificar a distribuição das lesões do vírus rábico no sistema nervoso central de casos espontâneos de raiva em ruminantes e comparar as técnicas de imunofluorescência direta (IFD), inoculação em camundongos (ICC) e presença de corpúsculos de Negri para o diagnóstico da doença foram analisados materiais proveniente de 48 casos de raiva, incluindo amostras de córtex frontal, temporal, parietal e occipital, hipocampo, tálamo, colículo rostral e caudal, cerebelo, ponte, medula oblonga, núcleo da base e porções da medula cervical, torácica e lombar. De 48 amostras analisadas, todas foram positivas na IFD e na ICC e em 30 (62,5 por cento) foram encontrados corpúsculo de Negri (CN). No entanto, houve diferenças importantes no resultados dos três testes nas diferentes regiões do SNC avaliadas. Nos cortes de córtex cerebral, em 38 bovinos, a presença de corpúsculos de inclusão foi baixa (11 por cento-37 por cento) assim como a positividade para IFD e ICC (60-80 por cento). Pelo contrário, todas as amostras de ponte, tálamo e medula testados foram positivas para IFD e ICC. Em outras regiões do tronco encefálico e também no cerebelo a positividade para ICC e IFD foi de 60 por cento a 96,7 por cento. No cerebelo foi encontrada a maior frequência (88,2 por cento) de corpúsculos de inclusão. Em oito ovinos as provas de ICC e IFD foram positivas em todos os cortes e foram observados corpúsculos de inclusão em três animais. Foram analisados somente dois casos de caprinos encontrando-se corpúsculos de inclusão em um e ambos foram positivos para IFD e ICC. Os resultados obtidos nesse trabalho sugerem que a conduta recomendada pelo Manual Técnico de Controle da Raiva dos Herbívoros (MTCRH) permite o diagnóstico de raiva associando o estudo histológico aos testes de IFD e ICC que incluem cerebelo, tálamo e tronco encefálico que apresentam alta positividade para as provas de IFD e ICC. No entanto, a melhor conduta é a de incluir metade do encéfalo cortado longitudinalmente e amostras de medula. Isto permite examinar por IFD e ICC uma ou mais regiões onde essas provas apresentam maior positividade e, posteriormente, se essas provas fossem negativas, retornar ao material original e examinar outras regiões. Por outro lado, a coleta de amostras dos locais recomendados pela MTCRH, assim com a coleta de metade do encéfalo, podem prejudicar o diagnóstico de outras doenças para o qual é necessário o estudo de todo o encéfalo após a fixação em formaldeído, para constatar a simetria e a distribuição das lesões. Nestes casos, com base nos resultados obtidos neste trabalho, pode ser recomendado para diagnóstico laboratorial de raiva o envio exclusivo de porções da medula cervical, dorsal e lombar, já que as três porções apresentaram 100 por cento de positividade nas provas de IFD e ICC. Além disso, o estudo histológico de todas as porções do cérebro incluídas neste trabalho permitirá complementar o diagnóstico.

With the aim to study the distribution of lesions the rabies virus in spontaneous cases of rabies in ruminants and to determine the efficiency of the direct fluorescent antibody test (DFA), mouse inoculation (MI) and presence of Negri bodies in the diagnosis of the disease, 48 cases of the rabies were examined. Samples of frontal, temporal, parietal and occipital cerebral cortex, hippocampus, thalamus, rostral and caudal colliculi, cerebellum, pons, medulla oblongata, basal nuclei and sections of the cervical, thoracic and lumbar spinal cord were examined. Of the 48 samples examined all were positive on DFA and MI, and in 30 (62.5 percent) Negri bodies were observed. However there were differences in the results of the three tests among different regions of the central nervous system. In the samples of the cerebral cortex in 38 cattle, the frequency of inclusion bodies was low (11-37 percent), and so was the positivity to DFA and MI (60-80 percent). In contrast, all samples of thalamus, pons and spinal cord were positive to DFA and MI. In other regions of the brain stem, positivity to these tests varied between 60 percent and 96.7 percent. On histologic examination, the major frequency of Negri bodies (88.2 percent) was observed in the cerebellum. In eight sheep the DFA and MI tests were positive in all sections of the CNS examined and Negri bodies were found in three sheep. Only two goats were examined; both were positive in DFA and MI tests and in one Negri bodies were found. These results suggest that the recommendations of the Brazilian Technical Manual for Rabies of Herbivores is adequate for rabies diagnosis, because their recommendations include the histologic study and the examination of cerebellum, and sections of the brainstem with high positivity to DFA and MI tests. However, a better recommendation is to send for DFA and MI half of the brain cut longitudinally and samples of the spinal cord, which will permit to examine one or two sections, and if those are negative to get back to the material and examine the rest of the sections. In contrast, to collect samples of the brain or half brain can be inappropriate for the diagnosis of other diseases of the CNS, for which the study of the whole fixed brain is necessary to recognize the symmetry or distribution of lesions. In these situations by the results obtained here, it can be recommended to send different sections of the spinal cord for DIF and MI tests and to fix the whole brain for gross and histologic examinations.

The clinicopathological study of infantile cytomegalovirus hepatitis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the clinicopathological features of infantile cytomegalovirus hepatitis.</p><p><b>METHOD</b>Liver biopsies from 30 cases of infantile cytomegalovirus hepatitis were observed under optical microscope and electronic microscope.</p><p><b>RESULT</b>The main clinical manifestations were jaundice, splenohepatomegaly and hypohepatia. Laboratory test showed dysfunction of liver, high level of CMV DNA, and high titer of anti-CMV antibody. Imaging examination demonstrated hepatomegaly. The histological changes were hepatocellular degeneration, necrosis, apoptosis, and fibrosis. The histological characteristics of cytomegalovirus hepatitis, including intranuclear inclusions in multinucleated giant cells and pseudo-lumens, were also observed under optical microscope. In addition, virion was observed in the nuclei and cytoplasm of hepatocytes under electronic microscope.</p><p><b>CONCLUSION</b>The viral DNA and serological tests have limited utility for the diagnosis of infantile cytomegalovirus hepatitis, and the final diagnosis depends on histopathology.</p>

Hallazgos patológicos en cerdos afectados con el síndrome del desmedro multisistémico postdestete de la República Argentina / Pathological findings in pigs affected by the postweaning multisystemic wasting syndrome in Argentina

El síndrome del desmedro multisistémico postdestete (PMWS) fue descrito por primera vez en Canadá en el año 1991 y desde entonces un número creciente de casos han sido diagnosticados en todo el mundo. En la Argentina, el PMWS fue reportado por primera vez recientemente. Se estudiaron 48 cerdos de 5 a 12 semanas de edad con signos característicos de PMWS procedentes de 19 granjas. Si bien se desconoce la distribución real del virus en nuestro país se observó desde el año 2001 un número creciente de granjas con PMWS y distribuidas en las principales provincias productoras. La histopatología fue una herramienta diagnóstica importante en casos sospechosos de PMWS con la observación de diferentes grados de lesión. En los animales estudiados las infecciones secundarias pudieron ser importantes, ya sea por patógenos oportunistas o por complicaciones bacterianas.

Postweaning multisystemic wasting syndrome was first described in Canada in 1991 and at present an increasing number of cases has been diagnosed worldwide. In Argentina the first cases of PMWS were reported recently. Forty eight 5 to 12 week old pigs with signs characteristic of PMWS from 19 farms were studied. Although the real distribution of the virus in our country is not known it was observed an increasing number of farms with PMWS distributed in the major producing provinces. The histopathology was an important tool in diagnosis of suspicious cases of PMWS with the observation of different degrees of lesion. In the studied animals, the secondary infections, either by opportunistic pathogens or secondary bacteria could be important.

Carboxyl terminus truncated human papillomavirus type 58 L1 protein maintains its bioactivity and ability to form virus-like particles / 华中科技大学学报（医学）（英德文版）

To prepare carboxyl terminus truncated human papillomavirus type 58 L1 (HPV58L1) protein and evaluate its ability to form virus-like particles, the baculovirus and Sf-9 insect cells was used to express HPV58L1 protein, and pFastBac-Htb containing HPV58L1 gene sequence of carboxyl terminus truncation was generated. Then Sf-9 cells were infected with recombinant baculovirus. After being cultured, the post-infected cells expressing--HPV58L1 protein were harvested and analyzed by SDS-PAGE and Western blot. The ProBond purification system was used for protein purification. The bio-activity of purified protein was identified by mouse erythrocyte hemagglutination assay, and the VLP formation was examined with transmission electron microscope. Our results showed that the recombinant baculovirus was generated and the Sf-9 cells was infected with the recombinant baculovirus, and after collecting, total cellular proteins were extracted. Truncated HPV58L1 protein with MW 58KD was revealed by SDS-PAGE and confirmed by Western blot. The purified L1 proteins under native condition could cause mouse erythrocytes to agglutinate and form VLP. It is concluded that HPV58L1 protein with carboxyl terminus truncation could be efficiently expressed. In baculovirus Sf-9 cells expression system, the purified protein could self-assemble into virions in vitro, and induce agglutination of mouse erythrocytes, indicating that carboxyl terminus truncation does not interfere with the bioactivity of HPV58L1 protein.

Isolation of etiological agent of hydropericardium syndrome in chicken embryo liver cell culture and its serological characterization.

The virus causing hydropericardium syndrome was isolated in chicken embryo liver (CEL) cell culture from livers obtained from naturally infected broilers. The cytopathic effects characterized by rounding and degeneration of cells were visible 36 hr post infection in first passage. At 4th passage level, the infectivity titre was 5.24 log10 TCID50/ml. In May-Grunwald and Giemsa stained cells, basophilic intranuclear inclusions ('bird eye' inclusion), typical of aviadenovirus infection, were observed. The specificity of inclusion was confirmed by indirect immunofluorescence. Various serological tests, such as agar gel precipitation test, counter immuno electrophoresis, micro serum neutralization test and enzyme linked immunosorbent assay were also standardized to confirm the isolation of etiological agent of hydropericardium syndrome in CEL cell culture and to diagnose the disease in poultry.

Experience of human rabies in north India.

Rabies is one of the most common causes of human encephalitis in developing countries. This study shows the diagnosis of rabies among suspected human rabies encephalitis cases by Seller stain, Flourescent stain as well as mouse inoculation test. Out of 71 postmortem brain specimens, 26 were diagnosed as rabies positive. Negri bodies were demonstrated in 18 (25.4%) brain saples by Seller stain. Flourescent antibody technique could detect rabies antigen in 21 (29.6%) samples. Rabies virus could be isolated in 15 (42.9%) of the 35 samples by intracerebral inoculation in 15 (42.9%) of the 35 samples of intracerebral inoculation in newborn Swiss albino mice. Of the 26 confirmed cases, 61.5% occurred during the months of June to August and history of dog bite was present in 9 (34.6%) cases.

Inclusion bodies induced by Bean rugose mosaic comovirus seen under light microscopy/

Two types of inclusion bodies were consistently observed under light microscopy in bean (Phaseolus vulgaris) leaf tissue infected with Bean rugose mosaic virus (BRMV), a species of the genus Comovirus, family Comoviridae. One type consisted of vacuolated inclusions found mainly in the cytoplasm of epidermal cells. The other type consisted of abundant crystalloid inclusions of different sizes and shapes found consistently in glandular hairs, guard cells, phloem tissue, xylem elements and occasionally in epidermal and mesophyll tissues. The two types of inclusion bodies stained with Azure A and Luxol Brilliant Green Bl-Calcomine Orange 2RS (O-G), and were similar to those seen to be caused by other species of comoviruses.

Un caso de encefalitis rábica de larga evolución: correlación clínico patológica / Human rabies encephalomyelitis of long survival: clinical pathological correlation

Se presenta el caso de un hombre de 22 años de edad que desarrolló encefalomielitis rábica de seis semanas de duración, y que fue tratado inicialmente como padecimiento psiquiátrico y después como encefalitis. Se destaca: 1.- El prolongado tiempo de evolución, ya que lo habitual es que la mayoría de los pacientes fallezcan durante los ocho días posteriores al establecimiento del diagnóstico. 2.- La evidente gliosis reactiva. 3.- Los cuerpos de inclusión en casi todos los cortes estudiados, tanto en la porción supra como en la infratentorial. 4.- Los cuepos de Negri únicos o múltiples y algunos gigantes en las neuronas del hipocampo, así como en las astas anteriores de la médula espinal. 5.- La proliferación de la microglia y la presencia de cuerpos acidófilos libres en el neurópilo. Todo lo anterior indica una larga evolución desde el punto de vista microscópico, lo que raramente se presenta en esta enfermedad. Se revisó la bibligrafía y se encontraron sólo diez casos de larga duración

Conceptos actuales sobre hepatitis viral / Current concepts on viral hepatitis

Contiene:Serologia de la hepatitis viral,metotos de diagnostico laboratorial en las hepatitis virales, nuevos metodos de diagnostico para el virus de la hepatitis B y C, estado actual de la hepatitis A, mutantes del virus B de la hepatitis y sus implicociones clinicas, infeccion por virus C, hepatitis E, manual de diagnostico y tratamiento de las hepatotias virales

Enfermedad por citomegalovirus (CMV): estudio morfológico de 24 casos de autopsia / Cytomegalovirus disease: pathological findings in 24 autopsies

Con el aumento de la sobrevida de pacientes inmunodeprimidos la enfermedad por CMV ha cobrado cada vez más importancia. Su diagnóstico se basa frecuentemente en estudios morfológicos. Los objetivos de esta revisión de autopsias fueron: a) delimitar los patrones morfológicos de la enfermedad por CMV; b) determinar el posible rol del CMV como causa de muerte y c) conocer la relación entre la condición de base del paciente y la extensión de la enfermedad. Se reunieron 24 casos. En 13 se encontraron inclusiones virales en más de un órgano. El pulmón fue el órgano más afectado (19 casos), seguido del hígado (7), suprarrenal y colon (5) y riñón, bazo e intestino delgado (4). En 20 casos (83 por ciento) se encontró una condición basal inmunodepresiva; neoplasia maligna (6 casos), sindrome de inmunodeficiencia (5), tratamiento inmunusupresor por patología no tumoral (4) y otros (5). El 54 por ciento de las autopsias presentó otras infecciones asociadas; micótica (8 casos), bacteriana (5), viral (2) y parasitaria (1). En 9 casos se consideró el CMV causa posible de muerte y en 5 fue la única causa posible encontrada. Los grupos con neoplasias y sindrome de inmunodeficiencia presentaron una enfermedad por CMV más extensa y el patrón pulmonar más frecuentemente encontrado como causa de muerte fue daño alveolar difuso y bronconeumonia extensa

Diagnóstico de hepatitis con cuerpos de inclusión mediante la prueba de inmunofluorescencia / Inclusion body hepatitis diagnosis by the immunofluorescence test

Se elaboró un conjugado para diagnóstico de hepatitis con cuerpos de inclusión (HCI). Para ello se utilizaron 60 pollos de engorda Arbor Acres, los cuales permanecieron en unidades de aislamiento durante 59 días. A partir de la 2a semana de edad, las aves fueron inmunizadas semanalmente con adenovirus tipo 1; se obtuvo un suero hiperinmune contra el virus utilizado. El suero obtenido permitió la elaboración de un conjugado contra adenovirus tipo 1. Se evaluó la especificidad del conjugado, usando como referencia 14 casos positivos a HCI diagnosticados por histopatología. Finalmente, se infectaron cultivos celulares de fibroblastos de embrión de pollo con adenovirus tipo I, luego se realizó en ellos la prueba de inmunofluorescencia, utilizando testigos negativos. Los resultados muestran que la técnica de inunofluorescencia es de gran confiabilidad para el diagnóstico de HCI.

Vacunas experimentales contra hepatitis a cuerpo de inclusión aviar. I valoración serológica / Experimental vaccines against avian inclusion body hepatitis. I. Serological evaluation

Se elaboraron dos vacunas experimentales (Vac-19 y Vac-28) de Hepatitis a Cuerpo de Inclusión (HCI) a partir de los serotipos 4,10 y 11, aislados en brotes de campo en el país. Las cepas se atenuaron por pasajes en huevos embrionados SPF (16 y 22 pasajes para ambas vacunas) y cultivo de células renales (3 y 6 pasajes respectivamente). Se utilizaron cuatro grupos (G) experimentales: G I y G II formado por 8 pollos cada uno, vacunados vía oral (4,4 DICC55/ml) con Vac-19 y Vac-28 respectivamente a la tercera semana y revacunados a los 35 días por igual vía y dosis. Los grupos G III y G IV con 5 pollos cada uno correspondieron a control positivo y negativo, ambos grupos sin vacunar, el primero solo desafiado con un pool de los serotipos 4,10 y 11, a los 45 días de edad y el último sin desafiar. Exámenes clínicos serológicos se realizaron previo y posterior a las vacunaciones y desafío. La respuesta inmune se midió, a través de Inmunodifusión en Gelosa (IDG) y Seroneutralización (SN) en Cultivo de Células Renales (CCR) por el método ß (200 DICC50/50*l). Mediante la prueba IDG se observaron reacciones positivas (100%) desde el día 43 en adelante en los grupos cavunados y desde el 55 en el grupo desafiado (GIII). Los Títulos Medios Geométricos (TMG) previo al desafío fueron G I de 1.194 y en G II 23.525. Con posterioridad al desafío se observó un TMG de 7.760 y . 305.736 respectivamente en ambos grupos. El G III tuvo un TMG de 640. No se observó signología clínica y mortalidad el desarrollo de la experiencia. Se concluye que solo Vac-28 originó protección a las aves, emdida por la respuesta inmune humoral, pero por las lesiones observadas en el grupo solo vacunado se debería continuar estudiando sucompleta atenuación