A. Ramis

Histological and immunohistochemical study of clinically normal skin of Leishmania infantum-infected dogs

Skin lesions are the most usual manifestation of canine leishmaniosis. The aim of this study was to investigate the histological pattern and parasite load in clinically normal skin of Leishmania-infected dogs. Two groups of Leishmania-infected dogs were studied. Group A consisted of 15 symptomless animals which, although seronegative or only mildly seropositive, gave a positive polymerase chain reaction (PCR) for Leishmania in the skin. Group B consisted of 20 clinically affected dogs which were highly seropositive and PCR-positive. Biopsies of normal skin from all dogs were processed for routine histology and Leishmania immunohistochemistry. The study demonstrated microscopical lesions and the presence of parasites in the skin from dogs of group B, but not group A. The results cast doubt on the relevance of infected but symptomless dogs in the epidemiology of canine leishmaniosis. In contrast, however, the clinically normal skin of sick dogs harbours the parasite and probably plays a role in the transmission of leishmaniosis.

Detection of T lymphocytes in canine tissue embedded in paraffin wax by means of antibody to CD3 antigen

This report describes the immunocytochemical detection of CD3 antigen by means of a polyclonal antibody in sections of formol-fixed canine lymphoid tissue, embedded in paraffin wax. In all hybrid organs the lymphocytes in the T cell regions showed an intense immune reaction, located particularly in the cytoplasmic membrane and at the cytoplasmic border.

Distribution patterns of influenza virus receptors and viral attachment patterns in the respiratory and intestinal tracts of seven avian species

This study assessed the presence of sialic acid α-2,3 and α-2,6 linked glycan receptors in seven avian species. The respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, golden pheasant, ostrich, and mallard were tested by means of lectin histochemistry, using the lectins Maackia amurensis agglutinin II and Sambucus nigra agglutinin, which show affinity for α-2,3 and α-2,6 receptors, respectively. Additionally, the pattern of virus attachment (PVA) was evaluated with virus histochemistry, using an avian-origin H4N5 virus and a human-origin seasonal H1N1 virus. There was a great variation of receptor distribution among the tissues and avian species studied. Both α-2,3 and α-2,6 receptors were present in the respiratory and intestinal tracts of the chicken, common quail, red-legged partridge, turkey, and golden pheasant. In ostriches, the expression of the receptor was basically restricted to α-2,3 in both the respiratory and intestinal tracts and in mallards the α-2,6 receptors were absent from the intestinal tract. The results obtained with the lectin histochemistry were, in general, in agreement with the PVA. The differential expression and distribution of α-2,3 and α-2,6 receptors among various avian species might reflect a potentially decisive factor in the emergence of new viral strains.

Pathogenesis and transmissibility of highly (H7N1) and low (H7N9) pathogenic avian influenza virus infection in red-legged partridge ( Alectoris rufa )

An experimental infection with highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian influenza virus (LPAIV) was carried out in red-legged partridges (Alectoris rufa) in order to study clinical signs, gross and microscopic lesions, and viral distribution in tissues and viral shedding. Birds were infected with a HPAIV subtype H7N1 (A/Chicken/Italy/5093/1999) and a LPAIV subtype H7N9 (A/Anas crecca/Spain/1460/2008). Uninoculated birds were included as contacts in both groups. In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi. The presence of viral antigen in tissues and viral shedding were confirmed by immunohistochemistry and quantitative real time RT-PCR (qRRT-PCR), respectively, in all birds infected with HPAIV. However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges. In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals. The present study demonstrates that the red-legged partridge is highly susceptible to the H7N1 HPAIV strain, causing severe disease, mortality and abundant viral shedding and thus contributing to the spread of a potential local outbreak of this virus. In contrast, our results concerning H7N9 LPAIV suggest that the red-legged partridge is not a reservoir species for this virus.

Diagnosis of psittacine beak and feather disease (PBFD) viral infection, avian polyomavirus infection, adenovirus infection and herpesvirus infection in psittacine tissues using DNA in situ hybridization

The evaluation of the usefulness of DNA probes in a diagnostic setting to identify nuclear inclusions in selected viral infections (psittacine beak and feather disease viral infection, avian polyomavirus infection, adenovirus infection and Pachecos parrot disease) is reported. A DNA in situ hybridization method was used to detect viral nucleic acid in sections of paraffin-embedded tissues coming from birds naturally and/or experimentally infected. It is concluded that DNA probes used for polyomavirus (FN-19) and adenovirus (FN-23) are able to identify nucleic acid of each virus in the cells with nuclear inclusions, and when used for psittacine beak and feather disease virus (FN-8), and Pachecos parrot disease virus (FN-49) are able to detect viral nucleic acid in cells with or without inclusions.

Detection of feline infectious peritonitis virus-like antigen in ferrets

SIR, – Feline infectious peritonitis (FIP) is caused by feline coronavirus (FCoV). It is a well known and widely distributed coronavirus- induced systemic disease in cats and non-domestic felids ([O’Reilly and others 1979][1], [Kennedy and others 2002][2]). The disease is characterised by

Identification of Group 1 Coronavirus Antigen in Multisystemic Granulomatous Lesions in Ferrets (Mustela putorius furo)

Summary Tissues from nine ferrets with granulomatous lesions similar to those seen in feline infectious peritonitis were examined histopathologically and immunohistochemically. Four main types of lesions were observed: diffuse granulomatous inflammation on serosal surfaces; granulomas with areas of necrosis; granulomas without necrosis; and granulomas with neutrophils. Other less commonly seen lesions were granulomatous necrotizing vasculitis and endogenous lipid pneumonia. FCV3-70 monoclonal antibody produced immunolabelling of group 1 coronavirus antigen in tissue samples from eight animals, the antigen being present in the cytoplasm of macrophages in the different types of granulomatous lesions.

Turkey rhinotracheitis virus and Escherichia coli experimental infection in chickens: histopathological, immunocytochemical and microbiological study

The aim of this study was to evaluate the response of chickens to a combined infection with turkey rhinotracheitis virus (TRTV) and Escherichia coli O78:K80. Groups of specific-pathogen-free chickens were inoculated by eyedrop and intranasal routes with TRTV and/or E. coli O78:K80. Presence of E. coli O78:K80, histopathological changes and tissue distribution of viral antigen in the respiratory tract of chickens were evaluated. Dual infection resulted in increased severity of clinical signs, and macroscopic and microscopic lesions compared with those groups given single infections. All 36 chickens inoculated with TRTV plus E. coli O78:K80 showed severe rhinitis. Moreover, periorbital edema and fibrinous airsacculitis and pericarditis were observed in one of the three chickens inoculated with both agents and sacrificed at day 5 p.i. In addition, purulent material in the air spaces of the cranial bones was seen in three of the six animals from the same group sacrificed at days 5 and 7 p.i. The distribution of viral antigen in tissues was similar in groups inoculated with TRTV and TRTV plus E. coli, but viral antigen was detected only in main bronchi of chickens from the latter group. The quantity of E. coli O78:K80 isolated from the nasal cavity was greater in the group given dual infection. The results obtained suggest that TRTV may act as primary agent, enhancing E. coli multiplication. The lesions observed in the group inoculated with both agents could correspond to an initial stage of swollen head syndrome (SHS) and contribute to the hypothesis that SHS could be due to a mixed infection with TRTV and E. coli.

Adenovirus Hepatitis in a Boa Constrictor (Boa Constrictor)

A boa constrictor was submitted for postmortem evaluation. At necropsy, there were no substantial lesions except in the liver. Light microscopy revealed severe multifocal to coalescing coagulative necrotic hepatitis, with basophilic and eosinophilic intranuclear inclusions in hepatocytes within the necrotic foci. The histopathological findings suggested a viral hepatitis. An adenoviral infection was diagnosed by means of transmission electronic microscopy and in situ hybridization techniques.

Persistence of highly pathogenic avian influenza virus (H7N1) in infected chickens: feather as a suitable sample for diagnosis.

Selection of an ideal sample is a vital element in early detection of influenza infection. Rapid identification of infectious individuals or animals is crucial not only for avian influenza virus (AIV) surveillance programmes, but also for treatment and containment strategies. This study used a combination of quantitative real-time RT-PCR with an internal positive control and a cell-titration system to examine the presence of virus in different samples during active experimental AIV infection and its persistence in the infected carcasses. Oropharyngeal/cloacal swabs as well as feather pulp and blood samples were collected from 15-day-old chicks infected with H7N1 highly pathogenic AIV (HPAIV) and the kinetics of virus shedding during active infection were evaluated. Additionally, several samples (muscle, skin, brain, feather pulp and oropharyngeal and cloacal swabs) were examined to assess the persistence of virus in the HPAIV-infected carcasses. Based on the results, feather pulp was found to be the best sample to detect and isolate HPAIV from infected chicks from 24 h after inoculation onwards. Kinetic studies on the persistence of virus in infected carcasses revealed that tissues such as muscle could potentially transmit infectious virus for 3 days post-mortem (p.m.), whilst other tissues such as skin, feather pulp and brain retained their infectivity for as long as 5-6 days p.m. at environmental temperature (22-23 degrees C). These results strongly favour feather as a useful sample for HPAIV diagnosis in infected chickens as well as in carcasses.