Development of a hyperimmune equine serum therapy for COVID-19 in Argentina

The disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date. Equine polyclonal antibodies (EpAbs) put forward a sound alternative. The new generation of processed and purified EpAbs containing highly purified F(ab’)2 fragments demonstrated to be safe and well tolerated. EpAbs are easy to manufacture allowing a fast development and scaling up for a treatment. Based on these ideas, we present a new therapeutic product obtained after immunization of horses with the receptor-binding domain of the viral Spike glycoprotein. Our product shows around 50 times more potency in in vitro seroneutralization assays than the average of convalescent plasma. This result may allow us to test the safety and efficacy of this product in a phase 2/3 clinical trial to be conducted in July 2020 in the metropolitan area of Buenos Aires, Argentina.

La enfermedad denominada COVID-19 es causada por el coronavirus SARS-CoV-2 y es actualmente considerada una pandemia a nivel global. El desarrollo de vacunas es sin duda la mejor estrategia a largo plazo, pero debido a la emergencia sanitaria, existe una necesidad urgente de encontrar soluciones rápidas y efectivas para el tratamiento de la enfermedad. Hasta la fecha, el uso de plasma de convalecientes es la única inmunoterapia disponible para pacientes hospitalizados con COVID-19. El uso de anticuerpos policlonales equinos (EpAbs) es otra alternativa terapéutica interesante. La nueva generación de EpAbs incluyen el procesamiento y purificación de los mismos y la obtención de fragmentos F(ab’)2 con alta pureza y un excelente perfil de seguridad en humanos. Los EpAbs son fáciles de producir, lo cual permite el desarrollo rápido y la elaboración a gran escala de un producto terapéutico. En este trabajo mostramos el desarrollo de un suero terapéutico obtenido luego de la inmunización de caballos utilizando el receptor-binding domain de la glicoproteína Spike del virus. Nuestro producto mostró ser alrededor de 50 veces más potente en ensayos de seroneutralización in vitro que el promedio de los plasmas de convalecientes. Estos resultados nos permitirían testear la seguridad y eficacia de nuestro producto en ensayos clínicos de fase 2/3 a realizarse a partir de julio de 2020 en la zona metropolitana de Buenos Aires, Argentina.

Respuesta anticlases mayores de anticuerpos humanos séricos en antisueros hiperinmunes obtenidos en carneros / Characterization of hyperimmune anti-human serum produced in sheep

Introducción: La inmunoelectroforesis es una técnica de precipitación que permite la caracterización de muestras biológicas complejas. En el Departamento de Inmunología del Instituto de Ciencias Básicas y Preclínicas Victoria de Girón se cuenta con un antisuero hiperinmune obtenido por inmunizaciones de carneros contra proteínas totales séricas humanas y con otro antisuero anti IgA de calostro humano. Objetivo: Identificar IgG, IgM e IgA en suero humano y determinar respuesta anti IgM humana en el antisuero anti IgA de calostro humano obtenido en carnero. Material y Métodos: Se realizó un estudio observacional, descriptivo y transversal desde noviembre de 2017 hasta junio de 2018. Se desarrolló una inmunoelectroforesis de suero humano normal empleando el antisuero hiperinmune. Resultados: Se identificaron IgG, IgM e IgA además de albúmina y otras fracciones proteicas y se determinó respuesta anti IgM humana en el antisuero anti IgA de calostro humano obtenido en carnero. Conclusiones: Este trabajo permitió identificar y determinar la respuesta anticlases mayores de inmunoglobulinas en la muestra de estudio(AU)

Introduction: Immunoelectrophoresis is a precipitation technique that allows the characterization of complex biological samples. The Immunology Department of the Institute of Basic and Pre-Clinical Sciences Victoria de Girón has a hyperimmune antiserum obtained by immunization of sheep against human serum total proteins and it also has an anti-human IgA antiserum obtained from human colostrum. Objective: The aim of this study was to identify IgG, IgM and IgA in human serum and to determine response to anti-human IgM in human colostral IgA with antiserum obtained in sheep. Material and Methods: An observational descriptive cross-sectional study was conducted from November 2017 to June 2018. Immunoelectrophoresis of normal human serum was performed using hyperimmune antiserum. Results: These procedures allowed to identify IgG, IgM and IgA in addition to albumin and other protein fractions and to determine response to anti-human IgM in human colostral IgA with antiserum obtained in sheep. Conclusions: This work allowed us to identify and determine significant anti-class responses of immunoglobulins in the sample studied(AU)

Pruebas dermatológicas con autosuero en pacientes alérgicos y en pacientes autistas y sus madres / Autoserum skin tests in allergic patients, and in autistic patients and their mothers

Introducción: las alergias se encuentran con frecuencia en pacientes autistas y asimismo el autismo muestra una gran presencia entre los pacientes alérgicos. Objetivo: demostrar que las alergias y el autismo comparten algunos patrones inmunológicos similares. Métodos: la prueba dermatológica con autosuero se utilizó para demostrar la presencia de anti-IgE y/o de anticuerpos de receptores de Ig/E (FcεRIα). Resultados: la prueba ASST confirmó la frecuencia similar de positivos/positivos y de negativos/negativos en pacientes alérgicos y en pacientes autistas. Estas similitudes no existieron cuando se realizó la comparación con el grupo control. Se había hallado una correlación positiva con los resultados obtenidos en pacientes autistas y sus madres. Conclusiones: los pacientes autistas y los pacientes alérgicos comparten ciertas similitudes inmunológicas. Ambos se diferencian del grupo de controles sin estas condiciones. Resulta frecuente encontrar pacientes autistas con síntomas alérgicos y pacientes alérgicos con signos de autismo. Es motivo de análisis si los hallazgos inmunológicos representan un puente clínico entre ambos procesos. Asimismo se mostró una posible correlación genética entre los pacientes con autismo y sus madres(AU)

Introduction: allergies are frequently found among patients with autism and autism shows an increased frequency among the allergic patients. Objective: to demonstrate that allergies and autism share some similar immunological patterns. Methods: the autoserum skin test (ASST) was used to demonstrate the presence of anti-IgE and/or anti-IgE receptor antibodies (FcεRIα). Results: the ASST demonstrated similar frequency, positives/positives and negatives/negatives, considering allergic and autistic patients. These similarities didn't exist when comparing with the control group. A positive correlation had been found with the results of autistic patients and their mothers. Conclusions: autistic and allergic patients share some immunological similarities. Both differ from normal controls. It is not uncommon autistics with allergic symptoms and allergic patients with autism. If the immunological findings represent a clinical bridge between both processes, it is under discussion. Also it was demonstrated a possible genetic correlation between the patients with autism and their mothers(AU)

Antisuero AA479: nuevo reactivo para la serotipificación de variantes atípicas se Shigella flexneri / AA479 antiserum: new reagent for the serotype characterization of atypical variants of Shigella flexneri

Shigella flexneri is divided into 13 serotypes based on the combination of antigenic determinants present in the O-antigen. A new O-antigen modification with phosphoethanolamine has been identified. The presence of this antigenic determinant (called E1037) is recognized by monoclonal antibody MASF IV-1. Given the increasing incidence of these new variants and the difficulty in supplying the monoclonal antibody to our country, we produced a polyclonal antiserum (AA479) through immunization with a S. flexneri Xv strain. The antiserum specificity was assessed by slide agglutination against isolates from clinical cases and a culture collection representing all Shigella serotypes. The results obtained demonstrated a 100% correlation between AA479 absorbed antiserum and monoclonal antibody MASF IV-1. The availability of AA479 antiserum in every public hospital in Argentina will allow us to identify atypical S. flexneri isolates in order to strengthen Shigella surveillance in our country and to compare with global epidemiological dat

Shigella flexneri se divide en al menos 13 serotipos sobre la base de la combinación de determinantes antigénicos presentes en el antígeno O. Se identificó una nueva modificación del antígeno O con fosfoetanolamina. La presencia de este determinante antigénico (denominado E1037) es reconocida por el anticuerpo monoclonal MASF IV-1. Teniendo en cuenta la incidencia creciente de estas nuevas variantes y la dificultad en la provisión del anticuerpo monoclonal para nuestro país, se elaboró un antisuero de tipo policlonal (AA479) mediante la inmunización con un cultivo de S. flexneri Xv. La especificidad del antisuero se evaluó por aglutinación en lámina con aislamientos clínicos y cultivos de colección, con lo que quedaron representados todos los serotipos de Shigella. Los resultados obtenidos demostraron una correlación del 100% entre el antisuero AA479 absorbido y el anticuerpo monoclonal MASF IV-1. La disponibilidad del antisuero AA479 en todos los hospitales públicos de Argentina permitirá identificar los aislamientos atípicos de S. flexneri; de esta forma se podrá fortalecer la vigilancia de Shigella en nuestro país y comparar con los datos epidemiológicos a nivel global

Effect of mouse antisera targeting the Phlebotomus papatasi midgut chitinase PpChit1 on sandfly physiology and fitness

In sandflies, the absence of the peritrophic matrix (PM) affects the rate of blood digestion. Also, the kinetics of PM secretion varies according to species. We previously characterised PpChit1, a midgut-specific chitinase secreted in Phlebotomus papatasi (PPIS) that is involved in the maturation of the PM and showed that antibodies against PpChit1 reduce the chitinolytic activity in the midgut of several sandfly species. Here, sandflies were fed on red blood cells reconstituted with naïve or anti-PpChit1 sera and assessed for fitness parameters that included blood digestion, oviposition onset, number of eggs laid, egg bouts, average number of eggs per bout and survival. In PPIS, anti-PpChit1 led to a one-day delay in the onset of egg laying, with flies surviving three days longer compared to the control group. Anti-PpChit1 also had a negative effect on overall ability of flies to lay eggs, as several gravid females from all three species were unable to lay any eggs despite having lived longer than control flies. Whereas the longer survival might be associated with improved haeme scavenging ability by the PM, the inability of females to lay eggs is possibly linked to changes in PM permeability affecting nutrient absorption.

Equine hyperimmune serum protects mice against Clostridium difficile spore challenge

Clostridium (C.) difficile is a common cause of nosocomial diarrhea in horses. Vancomycin and metronidazole have been used as standard treatments but are only moderately effective, which highlights the need for a novel alternative therapy. In the current study, we prepared antiserum of equine origin against both C. difficile toxins A and B as well as whole-cell bacteria. The toxin-neutralizing activities of the antibodies were evaluated in vitro and the prophylactic effects of in vivo passive immunotherapy were demonstrated using a conventional mouse model. The data demonstrated that immunized horses generated antibodies against both toxins A and B that possessed toxin-neutralizing activity. Additionally, mice treated with the antiserum lost less weight without any sign of illness and regained weight back to a normal range more rapidly compared to the control group when challenged orally with 10(7) C. difficile spores 1 day after serum injection. These results indicate that intravenous delivery of hyperimmune serum can protect animals from C. difficile challenge in a dose-dependent manner. Hence, immunotherapy may be a promising prophylactic strategy for preventing C. difficile infection in horses.

Inhibitory effect of antibodies against human chorionic gonadotropin on the growth of colorectal tumour cells.

Human chorionic gonadotropin (hCG) was initially believed to be secreted exclusively by the embryo with its primary function being “rescue” of the corpus luteum. However, recently it has been found that the hormone (or its individual subunits) is also secreted by many cancers and that in many cases secretion is associated with poor patient prognosis. In this study, we assessed the presence of hCG in colorectal cancer cells (CCL-253) and evaluated the anti-tumour effects of anti-hCG antibodies in vitro and in vivo. Anti-hCG antibodies were reactive with CCL-253, as revealed by confocal immunoflourescence microscopy; both cell surface and intracellular expression were observed. Western blot analysis showed that antibodies appeared to interact with several moieties, indicating a level of cross-reactivity. Anti-hCG antiserum specifically reduced the viability of tumor cells and the addition of complement increased in vitro anti-tumor effects. In nude mice implanted with CCL-253 cells, administration of anti-hCG antiserum caused a significant reduction in tumor volume; all treated animals survived, while mortality was observed in control animals. Results suggest that anti-hCG antibodies can mediate significant anti-tumor activity both in vitro and in vivo and lend support to the rationale of anti-hCG immunization in the therapy of gonadotropin- sensitive cancers.

Monoclonal auto-antibodies and sera of autoimmune patients react with Plasmodium falciparum and inhibit its in vitro growth

The relationship between autoimmunity and malaria is not well understood. To determine whether autoimmune responses have a protective role during malaria, we studied the pattern of reactivity to plasmodial antigens of sera from 93 patients with 14 different autoimmune diseases (AID) who were not previously exposed to malaria. Sera from patients with 13 different AID reacted against Plasmodium falciparum by indirect fluorescent antibody test with frequencies varying from 33-100 percent. In addition, sera from 37 AID patients were tested for reactivity against Plasmodium yoelii 17XNL and the asexual blood stage forms of three different P. falciparum strains. In general, the frequency of reactive sera was higher against young trophozoites than schizonts (p < 0.05 for 2 strains), indicating that the antigenic determinants targeted by the tested AID sera might be more highly expressed by the former stage. The ability of monoclonal auto-antibodies (auto-Ab) to inhibit P. falciparum growth in vitro was also tested. Thirteen of the 18 monoclonal auto-Ab tested (72 percent), but none of the control monoclonal antibodies, inhibited parasite growth, in some cases by greater than 40 percent. We conclude that autoimmune responses mediated by auto-Ab may present anti-plasmodial activity.

Immunocytochemical study of gastrintestinal endocrine cells in insectivorous bats (Mammalia: Chiroptera) / Estudo imunocitoquímico das células endócrinas gastrintestinais de morcegos insetívoros (Mammalia: Chiroptera)

The regional distribution and relative frequency of endocrine cells in the stomach and intestine of Phyllostomidae: Lonchorhina aurita and Molossidae: Molossus molossus bats were studied immunohistochemically. Three types of immunoreactive (IR) endocrine cells - to serotonin (5-HT), gastrin (GAS) and enteroglucagon (GLUC) - were found in the gastric mucosa and four types of IR cells were identified in the intestinal mucosa. This study showed an interespecfic difference in the regional distribution and relative frequency of endocrine cells in the Chiropteran alimentary tract.

A distribuição regional e a freqüência relativa das células endócrinas no estômago e intestino dos morcegos insetívoros Phyllostomidae: Lonchorhina aurita e Mormoopidae: Molossus molossus foram estudadas pelo método de imunohistoquímica. Três tipos de células endócrinas imunorreativas (IR) à serotonina (5-HT), gastrina (GAS) e enteroglucagon (GLUC) foram localizadas na mucosa gástrica e quatro tipos de células endócrinas IR à 5-HT, GAS, colecistoquinina (CCK) e GLUC foram identificadas na mucosa intestinal. Este estudo mostrou uma diferença interespecífica na distribuição regional e na freqüência relativa das células endócrinas no trato alimentar de Chiropteros.

Production of polyclonal antibody against recombinant ORF 112 L of rock bream (Oplegnathus fasciatus) iridovirus (RBIV) and in vitro neutralization.

Rock bream iridovirus (RBIV) is a causative agent of epizootics among cultured rock bream (Oplegnathus fasciatus) in Korea. In this study, the immunogenic property of ankyrin repeats gene (ORF 112L) from RBIV was evaluated to develop vaccines against RBIV. ORF 112L of RBIV was cloned into expression vector of pGEX-4T-1. The recombinant protein was successfully expressed using E. coli BL21 (DE3). The soluble recombinant RBIV protein was applied to affinity column for the purification of the protein. Mice were immunized by the injection of purified recombinant protein to produce polyclonal antibodies. EUSA was carried out to identify the immune reaction abilities of polyclonal antibody to recombinant protein. The antigenic property of this protein was evaluated by using in vitro neutralization with BF-2 cells. In neutralization test, BF-2 cells infected with the mixture of RBIV and antisera containing anti-GST-ORF 112L polyclonal antibody were healthy showing few cytopathic effect (CPE) similar with the negative control (without RBIV). These studies suggest that the protein from the ankyrin repeats gene, ORF 112L of RBIV may play an important role in the mechanism of infection. Also, it can be possible to develop protein or gene vaccines using ORF 112L against RBIV.

Absence of experimental cross-protection induced by a Trypanosoma cruzi-like strain isolated from bats / Ausência de proteção cruzada experimental induzida por uma cepa Trypanosoma cruzi-like isolada de morcego

This study evaluated the possibility of inoculation and reinoculation with a trypanosomatid isolated from bats that is morphologically, biologically and molecularly similar to Trypanosoma cruzi, to protect against infection by virulent strains. Non-isogenic mice were divided into 24 groups that received from zero to three inoculations of Trypanosoma cruzi-like strain RM1, in the presence or absence of Freund’s adjuvant, and were challenged with the VIC or JG strains of Trypanosoma cruzi. Parasitemia and survival were monitored and animals were sacrificed for histopathological analysis. Animals immunized with Trypanosoma cruzi-like strain RM1 presented decreased parasitemia, independently of the number of inoculations or the presence of adjuvant. In spite of this reduction, these animals did not present any protection against histopathological lesions. Severe eosinophilic infiltrate was observed and was correlated with the number of inoculations of Trypanosoma cruzi-like strain RM1. These findings suggest that prior inoculation with this strain did not protect against infection but, rather, aggravated the tissue inflammatory process.

Este trabalho avaliou a possibilidade da inoculação e reinoculação de um tripanossomatídeo isolado de morcego, morfológica, biológica e molecularmente semelhante ao Trypanosoma cruzi, na proteção contra a infecção por cepas virulentas. Camundongos não-isogênicos foram divididos em 24 grupos, que receberam de zero a três inóculos da cepa RM1 de Trypanosoma cruzi-like, na presença ou ausência de adjuvante de Freund e desafiados com as cepas de Trypanosoma cruzi VIC ou JG. Acompanhou-se a parasitemia e a sobrevida e os camundongos foram sacrificados para análise histopatológica. Os animais imunizados com a cepa RM1 de Trypanosoma cruzi-like apresentaram redução da parasitemia, independente do número de inóculos ou presença de adjuvante. Apesar dessa redução, os animais não apresentaram proteção contra lesões histopatológicas e observaram-se intensos infiltrados eosinofílicos que foram correlacionados com o número de inóculos da cepa RM1 de Trypanosoma cruzi-like. Sugere-se que a inoculação prévia dessa cepa, ao invés de proteger contra a infecção, agravou o processo inflamatório tecidual.

Reversed passive hemagglutination test fails to detect HBsAg in a number of HBeAg positive sera.

In endemic areas of hepatitis B virus (HBV) infection, perinatal transmission from asymptomatic HBsAg carrier mothers to infants plays a major role in the transmission of HBV. HBeAg indicates a high level of viral replication and infectivity. Most of the infants born to HBeAg positive mothers become carriers. Prenatal screening of HBsAg would identify infected mothers and thus allow preventive administration of immunoglobulin and immunization to the newborns. Reversed passive hemagglutination assay (RPHA) is commonly used in Thailand for HBsAg screening. However this method has low sensitivity and gives false negative results. Therefore, infants born to HBsAg false negative mothers would not receive proper immunization. This study reveals the rate of false negative results for HBsAg by RPHA in high infectivity sera. Of 985 sera which were HBsAg positive by ELISA, 70 (7.1%) were negative for HBsAg by RPHA. Of these 70 false negative sera, 7 (10%) were HBeAg positive. Our results indicate that RPHA is a less sensitive method for detection of HBsAg than ELISA. RPHA can give false negative results even in sera with high HBV infectivity. Therefore, RPHA should be replaced by EIA for prenatal HBsAg screening or any other screening for HBV infection whenever possible.

Immunochemical Characterization of Brain and Pineal Tryptophan Hydroxylase

Recombinant mouse tryptophan hydroxylase (TPH) was expressed in Escheri-chia coli, using a bacterial expression vector and has been purified to homogeneity by sonication followed by Sepharose 4B column chromatography and native slab gel electrophoresis. This purified enzymatically active TPH protein was used for production of a specific antiserum. This antiserum identified the predicted TPH band (molecular weight, 54 kDa) on Western blot of crude extracts from the rat and mouse dorsal raphe, and the rat pineal gland. However, this antiserum recognized an additional protein band of lower molecular weight (48 kDa) in pineal extract. It is not clear whether the 48 kDa TPH band represents an isozyme or a protease cleavage product of TPH. Since the pineal gland contains higher TPH mRNA and lower TPH activity when it is compared with dorsal raphe nucleus enzyme, this lower molecular weight TPH may participate in the reduced TPH specific activity. In addition, there are no specific TPH inhibitors in the pineal gland and this lower molecular weight TPH is inactive or has a very low specific activity. This antiserum specifically immunostained serotonergic cell bodies in the dorsal raphe nuclei, some large caliber serotonergic processes in the dorsal raphe area as well as terminals in the olfactory bulb. It also immunolabeled the pineal gland and immunoprecipitated equally well TPH protein from the dorsal raphe nucleus and the pineal gland in a concentration-dependent manner.

Immunologic reactivity of a lipopolysaccharide-protein complex of type A Pasteurella multocida in mice

The immunologic reactivity of a lipopolysaccharide (LPS)-protein complex isolated from a potassium thiocyanate extract of a Pasteurella multocida (capsular type A and somatic type 3) strain was evaluated in mice. The LPS-protein complex provided 100% protection in mice against a challenge with the homologous strain. However, when the complex was fractionated into LPS and protein moieties by phenol-water treatment, both components lacked immunogenicity. The complex and extracted components were mitogenic for mouse B lymphocytes with the protein moiety the most active. Although immune serum against the LPS-protein complex protected mice against challenge thereby indicating a role for humoral immunity, the LPS-protein complex of P. multocida was also found to induce cell-mediated immunity. This cell-mediated immunity was demonstrated in mice immunized with the complex by: (1). mitogenic responses of T lymphocytes, (2). induction of delayed type hypersensitivity reaction in the hind footpads, and (3). enhanced resistance to challenge infection with Salmonella enteritidis.

Impacto de la administración y calidad del calostro sobre los niveles de inmunoglobulinas séricas en becerro / Impact of colostrum management and quality over serum immunoglobulin levels in claves

La hipogamaglobulinemia se presenta muy frecuentemente en becerros, y es una de las causas más importantes de la morbilidad y mortalidad en estos animales. Cuando no existe una transferencia de inmunidad calostral apropiada se presentan diferentes grados de hipogamaglobulinemias. Se determinaron la densidad y la concentración de proteínas en el suero del calostro del primer ordeño de 305 vacas. Se registró el volumen de calostro consumido por parte de los becerros nacidos de esas vacas y se tomó el tiempo posparto del consumo. Las concentraciones séricas de proteínas totales se determinaron por método de Biurete e inmunoglobulinas (Ig) con la técnica de turbidez con sulfato de zinc. Se determinó una relación directa entre la densidad del calostro y las proteínas en suero de calostro, así como de proteínas de suero de calostro con las proteínas e Ig séricas del becerro. Los nivel de Ig en el suero sanguíneo de los becerros a los 2 a 4 días de edad dependen del volumen, tiempo y también significativamente de la calidad del calostro del primer consumo. Los niveles séricos de Ig fueron de 0-5 unidades de turbidez de sulfato de zinc (UTSZ) en 10.8 por ciento; de 6-10 UTSZ en el 21.3 por ciento, de 11-17 UTSZ en 33.5 por ciento y de 18 UTSZ en 34.4 por ciento, siendo esto becerros normoglobulinémicos. Cuando los animales consumen 2 litros de calostro de buena calidad (densidad >1.050) antes de 3 h y otra dosis dentro de las primeras 10 h posparto, alcanzan niveles séricos de 18 UTSZ. En la práctica diaria es muy importante evaluar la calidad del calostro que consumen los becerros, así como los niveles de Ig séricas a los 2 a 4 días, para garantizar una buena protección contra septicemias e infecciones

Detección de anticuerpos contra Leptospira interrogans en equinos dedicados a la producción de sueros hiperinmunes / Detection of Leptospira interrogans antibody in horses used for production of hyperimmune sera

Sueros de 106 equinos de 1 a 21 años (89 machos y 17 hembras), procedentes del Instituto Nacional de Higiene y dedicados a producir sueros hiperinmunes, fueron analizados por aglutinación microscópica (AM) contra 19 serovariedades de L. interrogans. Considerando el estado inmunológico de los equinos, se examinaron sueros con títulos 1:400 mediante inmunodifusión doble en agar (IDD) y contrainmunoelectroforesis (CIEF), para descartar reacciones inespecíficas. Con el mismo fin, se inocularon conejos con los antígenos utilizados en los equinos (virus rábico, toxoides tetánico y diftérico y venenos de alacrán y víbora) y se probaron por AM. Con reacciones 1:100, 83 por ciento de los equinos (88 de 106) fueron positivos a una o más serovariedades con títulos de hasta 1:6500. Las serovariedades con más reacciones positivas fueron: autumnalis, australis y pomona. Las serovariedades con títulos más altos fueron: autumnalis, cynopteri y pyrogenes (1:6400) y australis, celledoni, szwajizak e icterohaemorrhagiae (1:3200). La IDD detectó un caso de identidad inmunológica total entre virus rábico y L. pomona (suero 545). La CIEF no detectó líneas de precipitación. Ninguno de los conejos inmunizados mostró títulos contra leptospira

Observations on the effects of cysticercosis immune sera on cysticercosis by scanning electronmicroscopy.

Two antigens of Taenia solium cysticercus, cystic fluid antigen (CFA) and the culture medium antigen (CMA), were used respectively to immunize rabbits in order to obtain immunosera. The CMA immunoserum added to culture medium with cysticerci limited the activities of the bladder worms. By using the scanning electronmicroscope, we could observe particulate deposits on the surface of the scolices, suckers and necks of the worms. The CFA immunoserum group showed similar changes but the deposit was less than that on the worms in the former group and appeared mainly on the cystic wall. After adding complement to the two groups mentioned above, we found that the microcilia on the surface of the worms were swollen and were seriously damaged. The worms treated with praziquantel were damaged over large area of their surfaces and were affected deep into their tissues. The damaged parts of the worms were quite different between the two groups. CMA is secreted by the living worms and therefore the serum antibodies are more effective than CFA in anti-parasite activity.