Equine herpesvirus 1 (EHV-1) is the causative agent of abortion, perinatal foal mortality, neurological and acute respiratory diseases in horses. Conventional laboratory diagnosis involving viral isolation from aborted foetuses is laborious and lengthy and requires processing of samples within 24 h of collection, which is problematic for samples that come from long distances. The aim of this study was to develop a polymerase chain reaction (PCR) assay useful in Argentina to detect DNA sequences of EHV-1 in different tissues from aborted equine foetuses with variable quality of preservation and without the use of conventional DNA fenolic extraction. Several DNA extraction protocols and primers were evaluated. The amplification method was standardized and its specificity was analysed using 38 foetal samples of variable quality of preservation. Of the 38 different foetal tissues, nine livers, six spleens and two lungs in good preservation and eight livers, one spleen and four lungs in a poor state of preservation were positive for PCR. EHV-1 was recovered only from the nine livers, five spleens and two lungs in good preservation. No virus was isolated from the samples that were poorly preserved. Viral isolation was confirmed by cytopathic effect and indirect immunofluorescence. The specificity of the PCR results was confirmed by the restriction endonuclease digestion of PCR products and hybridization.

The genomes of 10 equine herpesvirus 1 (EHV-1) strains isolated in Argentina from 1979 to 1991, and a Japanese HH1 reference strain were compared by restriction endonuclease analysis. Two restriction enzymes, BamHI and BglII, were used and analysis of the electropherotypes did not show significant differences among isolates obtained from horses with different clinical signs. This suggests that the EHV-1 isolates studied, which circulated in Argentina for more than 10 years, belong to a single genotype.

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A western blotting (WB) procedure has been developed for detecting antibodies to bovine leukosis virus (BLV) in cattle sera. Two hundred and thirty three serum samples from naturally infected cattle with BLV virus and serial bleedings from experimentally BLV infected cows were used. An agar gel immunodiffusion test (AGID) was used for comparing with the results obtained by WB. The AGID positive sera showed a different degree of reactivity by WB test against the two most important viral antigens (gp51 and p24), or against one of them. Other proteins (gp30, p15, p12 and p10) were not detected with any AGID positive sera, being observed occasionally three bands corresponding to the p24 protein. Using sera obtained by BLV experimental inoculation, the antibodies directed to p24 appeared early (between the 2nd and 4th week post inoculation) and thereafter antibodies to gp51were detected in some animals. The analysis of field serum samples by AGID as compared to WB showed an agreement of 90.9%. Only 1.7% of sera were negative by AGID and positive by WB and 7.2% that were not conclusive by AGID and were defined by WB (4.2% as positive and 3.0% as negative).

Bovine leukaemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL). In Argentina, where a program to eradicate EBL has been introduced, sensitive and reliable diagnosis has attained high priority. Although the importance of the agar gel immunodiffusion test remains unchanged for routine work, an additional diagnostic technique is necessary to confirm cases of sera with equivocal results or of calves carrying maternal antibodies.Utilizing a nested shuttle polymerase chain reaction, the proviral DNA was detected from cows experimentally infected with as little as 5 ml of whole blood from BLV seropositive cows that were nonetheless normal in haematological terms. It proved to be a very sensitive technique, since it rapidly revealed the presence of the provirus, frequently at 2 weeks postinoculation and using a two-round procedure of nested PCR taking only 3 hours. Additionally, the primers used flanked a portion of the viral genome often employed to differentiate BLV type applying BamHI digestion. It is concluded that this method might offer a highly promising diagnostic tool for BLV infection.

This study evaluated an indirect immunofluorescence assay (IFA) to detect feline immunodeficiency virus infection (FIV) antibody in a comprehensive epidemiological survey of FIV in Argentina. IFA modified in our laboratory, was compared with two other immunoassays, western blot (WB) and a sandwich immunochromatographic commercial kit (SI), and also with a direct polymerase chain reaction (PCR) method that detects proviral DNA. IFA showed to be a test with high sensitivity and specificity, and could be useful as a diagnostic tool in epidemiological studies. The presence of a low percentage of results with non-specific reactivity in the IFA could be resolved with further testing or use of an alternative method.Keywords: feline immunodeficiency virus, immunofluorescence assay, western blot, polymerase chain reaction RESUMO Avaliou-se a técnica de imunofluorescência indireta (IFA) na detecção de anticorpos contra o vírus da imunodeficiência felina (FIV) numa pesquisa epidemiológica do FIV na Argentina. A IFA foi modificada e comparada com duas outras técnicas imunológicas: western blot (WB) e imunocromatografia em camadas (SI) com kit comercial e também com reação em cadeia de polimerase (PCR) para detecção do

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Resumen Se detectaron anticuerpos específicos contra Arteritis Viral Equina (AVE) por medio de tres técnicas serológicas: Fijación del Complemento (FC), Inmunofluorescencia Indirecta (IFI) y Seroneutralización (SN). La experiencia se realizó sobre 250 muestras de sueros obtenidos de equinos con una sintomatología similar a la referida para esta enfermedad (65 muestras) y sin sintomatología aparente (185 muestras) provenientes de las siguientes razas y localidades: American Trotter (Provincias de Buenos Aires y Córdoba), Sangre Pura de Carrera (Provincia de Buenos Aires), Criollos (Provincias de Buenos Aires) y Mestizos (Provincias de Corrientes y Buenos Aires). El porcentaje de reactores positivos fue del 9,2%. Se discute la factibilidad de los métodos empleados y la posible importancia de la enfermedad en el país. Zusammenfassung Infektiöse Arteritis des Pferdes: Nachweis von Antikörpern bei Pferden in Argentinien Seren von 250 argentinischen Pferden wurden mit Hilfe der Komplementbindungsreaktion, des indirekten Immunofluoreszenztestes und des Neutralisationstestes auf Vorkommen von Antikörpern gegenüber dem Virus der infektiösen Arteritis des Pferdes untersucht. Die Pferde gehörten vier verschiedenen Rassen an, 65 Tiere waren krank, 185 Tiere waren klinisch gesund. Bei 23 Pferden (9,2%) wurden Antikörper gegenüber dem Virus der infektiösen Pferdearteritis nachgewiesen. Summary Equine viral arteritis: Demonstration of antibodies in horses in Argentina Specific antibodies against Equine Viral Arteritis (EVA) were detected by the following serological methods: Complement‐Fixation, Indirect Immunofluorescence and Seroneutralization. The study was performed on 250 serum samples; 65 of them were obtained from horses presenting clinical signs consistent with the disease and 185 samples belonged to horses without any clinical signs. These sera were from the following breeds and provinces: Standardbreed (Buenos Aires and Córdoba Provinces), Thoroughbreed (Buenos Aires Prov.), Quarterhorse (Buenos Aires and Corrientes Provinces) and “Criollos” (Buenos Aires Prov.). The number of positive serum samples was 23 (9.2%). The factibility of the methods employed is discussed as well as the importance of the disease in Argentina. Résumé Artérite infectieuse du cheval: mise en évidence d'anticorps chez des chevaux en Argentine On a recherché des anticorps contre le virus de l'artérite infectieuse du cheval dans les sérums de 250 chevaux argentins avec la réaction de fixation du complément, le test d'immunofluorescence indirecte et le test de neutralisation. Les chevaux appartenaient à quatre races différentes, 65 animaux étaient malades et 185 animaux étaient cliniquement sains. Des anticorps contre l'artérite infectieuse du cheval ont été mis en évidence chez 23 chevaux (9,2%).