Nadia Analía Fuentealba

First report of Israeli acute paralysis virus in asymptomatic hives of Argentina

Honey bee mortality has recently been associated with Israeli acute paralysis virus (IAPV), a proposed etiological agent for a new syndrome known as Colony Collapse Disorder. Bees infected with this virus show shivering wings, progress into paralysis, and finally die outside the hive. During the last years, honey bee mortality became a serious problem for Argentinean beekeepers. We herein report the preliminary results of a survey carried out to detect IAPV in samples taken from several Argentine provinces, by using a reverse transcription Polymerase Chain Reaction assay. Our data indicate the existence of high frequency of IAPV in asymptomatic hives of Argentina.

Effects of Different Anesthetics in the Murine Model of EHV-1 Infection

Mice are commonly used as an experimental model to investigate the Equid herpesvirus 1 (EHV-1) infection. This model easily reproduces the disease, and the clinical signs are more or less similar to those observed in the horse, the natural host. During natural infection, the acute course of respiratory infection is mandatory for the development of adaptive immune response. Since interactions between EHV-1 and anesthetics are possible, the study investigated whether the early events of murine pulmonary immune response could be affected by different anesthetics. Therefore, mice were experimentally infected with a unique EHV-1 strain under the effects of ether, ketamine/xylazine, or isoflurane. Clinical signs and histopathological lesions in the lungs were described, and the cell death and proliferation rates of sham-inoculated or infected animals were quantified using immunohistochemistry. Clinical signs were more severe in animals anesthetized with ether. Qualitative differences in the recruited inflammatory cells were observed following application of anesthesia. The level of infection between the infected groups was not statistically significant. However, lungs from ketamine/xylazine-anesthetized animals showed the highest cell death rates, whereas those from isoflurane-anesthetized animals showed the highest proliferation rates. It has been emphasized that anesthetics alone or their interactions with EHV-1 modify the response against the infection. An appropriate selection of the anesthetic during experimental studies is relevant to minimize wrong conclusions.

Detection of equine herpesvirus 1 genome 1B in Argentina

To determine the genomic variation of equine herpesviruses (EHVs) isolated in Argentina between 1979 and the first half of 2004, DNA sequences from all 69 strains isolated were analysed. Sixty strains were recovered from aborted fetuses, one from leucocyte-rich plasma from a horse with respiratory signs and eight from cases of neonatal disease. The DNA was extracted from rabbit kidney epithelial (RK13) cells infected with each strain and digested with three restriction endonucleases (BamHI, Bg/II and KpnI). Two strains could be differentiated using BamHI restriction and were assigned to the EHV-1 1B prototype group. Only one of these two strains was typed EHV-1 1B with Bg/II. DNA digestion with KpnI was ineffective. The results obtained in this study demonstrate that the EHV-1 1B genome has been present in Argentina since at least 1996. The finding of two strains with this electropherotype suggests that there is genomic heterogeneity among Argentinian isolates.

Protective Effects of Intranasal Immunization with Recombinant Glycoprotein D in Pregnant BALB/c Mice Challenged with Different Strains of Equine Herpesvirus 1

Equine herpesvirus (EHV)-1 induces respiratory infection, neurological disorders and abortion in horses. Most of the currently available attenuated or inactivated vaccines against this infection are administered intramuscularly and only provide partial protection against the respiratory disease. The present study examines the effect of intranasal immunization with purified EHV-1 recombinant glycoprotein D (gD) in BALB/c mice followed by challenge with three different EHV-1 strains during early to mid-pregnancy. The induced viral infection was evaluated by virus isolation, DNA detection by polymerase chain reaction, histopathology and immunohistochemical localization of antigen in the lung, placenta and uterus. Non-immunized mice showed clinical signs of infection, positive virus isolation from lungs and uteri, and abortion induced by one of the virus strains. Endometrial lesions developed in some of these animals that have been described previously only in horses. Immunized mice and their offspring had no viral infection or typical lesions. Intranasally administered gD therefore induced partial or complete protection against three different EHV-1 strains in BALB/c mice.

Effects of equid herpesvirus 1 (EHV-1) AR8 and HH1 strains on BALB-c mice

Here, we used a murine model to describe and compare the pathogenic potential of the Argentinean equid herpesvirus 1 (EHV-1) AR8 strain with the Japanese HH1 reference strain. In AR8-inoculated animals, clinical signs began earlier, but the viremic phase was shorter. Virus isolation and DNA detection in the lungs, liver and spleen were positive for both strains at different times postinfection (pi). Infection foci produced by both strains were immunohistochemically detected in lungs from day 1 to day 4 pi. We conclude that whichever EHV-1 strain is selected to experimentally reproduce the disease, it needs appropriate standardization in order to provide valid conclusions.

Genomic study of Argentinean Equid herpesvirus 1 strains

Equid herpesvirus 1 (EHV-1) infection has a significant economic impact on equine production, causing abortion, respiratory disease, neonatal death and neurological disorders. The identification of specific EHV-1 genes related to virulence and pathogenicity has been the aim of several research groups. The purpose of the present study was to analyze different genomic regions of Argentinean EHV-1 strains and to determine their possible relationship with virulence or clinical signs. Twenty-five EHV-1 Argentinean isolates recovered from different clinical cases between 1979 and 2007 and two reference strains were amplified and sequenced. The sequence alignments were carried out using Clustal X version 1.92 and the putative amino acid sequences were deduced using Bio-Edit version 7.05. Minor changes were observed. No changes that could be involved in the different virulence in the mouse model of three EHV-1 Argentinean strains were found. No genetic variants were observed. The genomic regions analyzed are unsuitable for differentiation between abortigenic strains and those isolated from neonatal deaths.

Indirect ELISA (iELISA) for routine detection of antibodies against Minute Virus of Mice (MVM) in mice colonies

In this study we developed an indirect ELISA to detect antibodies against Minute Virus of Mice (MVM) using an antigen produced from BHK-21 cells infected with a prototype strain of the virus. The optimal antigen concentration and serum dilutions were established. In order to analyze variability in the laboratory, reproducibility and repeatability within and between plates were determined. Then, a panel of 460 sera from conventional facilities and previously classified as positive or negative by the indirect fluorescent antibody assay was analyzed. The cutoff value was determined by a receiver operating characteristic (ROC) curve. The results of the indirect ELISA were compared with those of the indirect fluorescent antibody assay. The ELISA assay showed 100% sensitivity and 99% specificity. ELISA is a useful tool to be developed in standard virology laboratories and can be used for screening animals faster than the traditional indirect fluorescent antibody assay.