Immunohistological diagnosis of rabbit haemorrhagic disease in experimentally infected rabbits in Spain.

The immunoreactivity of routinely processed liver and lung tissue samples obtained from rabbits inoculated with tissue explants from naturally infected animals when antisera directed against parvovirus from different species (canine, feline and porcine) as well as a RHD virus antiserum were employed has been tested by different immunoperoxidase methods. Cross-reactivity between RHD-virus antigens and parvovirus antigens was present. Best results were obtained with RHD and canine parvovirus antisera with the ABC method. The immunoreactivity in the liver was found in hepatocytes, Kupffer and bile duct cells. In the lung, it was exclusively observed in intravascular macrophages.     

Apoptosis of peripheral blood leukocytes from rabbits infected with non-haemagglutinating strains of rabbit haemorrhagic disease virus (RHDV)

The report demonstrates that the induction of apoptosis in peripheral blood granulocytes and lymphocytes of rabbits infected with three non-haemagglutinating RHDV strains (English Rainham, German Frankfurt, and Spanish Asturias) is a crucial determinant of the pathogenesis of rabbit haemorrhagic disease. Apoptosis was measured by flow cytometric detection of caspase activity. These studies demonstrated that the investigated RHDV (rabbit haemorrhagic disease virus) viral strains affected leukocyte apoptosis to varying degrees. Enhanced leukocyte apoptosis was detected between 4 and 36h after infection and was more pronounced in lymphocytes than in granulocytes. The data presented here thus provide a preliminary understanding of the kinetics of apoptosis in leukocytes of rabbits infected with RHDV.     

Immunohistochemical localisation of rabbit haemorrhagic disease virus VP-60 antigen in early infection of young and adult rabbits

This study evaluated the time course distribution of rabbit haemorrhagic disease virus (RHDV) structural protein VP60 in tissues from experimentally infected rabbits from three different age groups. Viral VP60 antigen could not be detected in tissue samples from animals under four weeks, and only a few hepatocytes (0.01 to 0.2 per cent) were stained in the 6-week-old animals. A 6-week-old rabbit euthanised at 72 hpi showed VP60-labelling in hepatocytes and macrophages close to areas of inflammation. Viral VP60 antigen was detected as early as 12 hpi in a few hepatocytes (0.03 per cent) from adult animals. Within this age group, the extent of hepatocyte labelling considerably increased at 18 (3.0 per cent), 24 (25.5 per cent), 36 (50 per cent) and 48 (60 per cent) hpi. Extrahepatic viral VP60 antigen was also detected at 36 and 48 hpi in spleen macrophages and lymphocytes from adult rabbits. These findings support the hypothesis that the hepatocyte is the only cell type in the liver able to support RHDV replication almost immediately after viral infection.     

Ingestion capacity of PMN cells in peripheral blood of rabbits experimentally infected with VHD (viral haemorrhagic disease) virus strains originating from various biotopes

The study presents results of investigations on ingestion capacity in rabbits experimentally infected with two French strains (Fr-1 and Fr-2) and four Polish strains (KGM, SGM, MAL, Kr-1) of VHD virus. The results proved that the strains studied exhibited distinct reactivity even if the VHD virus is thought to be uniform in the biological respect.     

Hepatic lesions in rabbits infected with Encephalitozoon cuniculi administered per rectum.

Microsporidia have been recognized recently as opportunistic pathogens in acquired immunodeficiency syndrome patients. In an attempt to develop an animal model of enteric microsporidiosis, adult (5 to 6 months old) male Flemish Giant rabbits from a closed New York colony were administered 5 x 10(3), 5 x 10(5), and 5 x 10(7) Encephalitozoon cuniculi per rectum. Rabbits given 5 x 10(5) and 5 x 10(7) E. cuniculi had moderate granulomatous periportal infiltrates, characterized by the presence of numerous macrophages, epithelioid cells and a few multinucleated giant cells, lymphocytes, and plasma cells. Inflammatory cells also were seen infiltrating the tunica adventitia and tunica media of hepatic portal veins and branches of the hepatic artery. This study demonstrates that administration of E. cuniculi per rectum to rabbits results in infection that is characterized by high frequency and severity of hepatic lesions.     

Suppression of immunological responses in rabbits experimentally infected with bovine leukemia virus

Ten 2- to 4-month-old rabbits were inoculated subcutaneously with bovine leukemia virus (BLV)-infected bovine or sheep cells. By 6 weeks after inoculation all ten rabbits had converted to BLV antibody-positive, and BLV or BLV antigen was detected in lymphocytes from most of the rabbits tested, although there were few antigen-producing cells. Three rabbits showed continuous respiratory symptoms after infection and one died with pneumonia. Humoral immune responses against mouse serum were significantly suppressed in BLV-infected rabbits compared with non-infected control rabbits. The lymphocyte blastogenesis response was also suppressed in BLV-infected rabbits. At the time of necropsy, six rabbits showed pulmonary lesions; however, none of the BLV-infected rabbits had tumors during an observation period of over 1 year.     

White and red blood cells picture in rabbits experimentally infected with RHD virus

Four strains of RHDV assigned as haemagglutinating (Vt97 and Hartmannsdorf) and non-haemagglutinating (Pv97 and 9905) antigenic variants were examined for dynamic changes in the values of white and red blood cells indexes. The study showed differences among strains examined that were not depending on haemagglutination property.     

Gastrointestinal motor disturbance in rabbits experimentally infected with Strongyloides papillosus

Strongyloides papillosus is a common nematode in ruminants, and the rabbit is the only susceptible experimental animal that has been identified to date. It is known that heavy infection with S. papillosus causes death in a number of animals. However, even though a number of fatal cases have been reported, the mechanism by which S. papillosus infection leads to death remains unknown. In this study, the pathogenic effect of S. papillosus infection on gastrointestinal motility in infected rabbits was investigated by radiographic means. Gastrointestinal motility in rabbits experimentally infected with S. papillosus was assessed by contrast radiography after oral administration of barium sulfate on days 11 (group A) and 13 (group B) of infection. Body weight, food intake, fecal weight and egg count per gram of feces (EPG) were examined in order to investigate the effect of infection on gastrointestinal motility. Seven rabbits from each S. papillosus-infected and uninfected group were examined. Significant declines in body weight, daily food intake, and fecal weight, as well as gastrointestinal motor disturbances, were observed in association with elevated EPG counts in infected rabbits. This was only observed during the intestinal phase of S. papillosus infection. These results suggest that gastrointestinal motor disturbances underlie the anorexia, weight loss and subsequent death observed in rabbits infected with adult stage S. papillosus.     

Tyzzer's disease in cats experimentally infected with feline leukaemia virus

Three cases of feline Tyzzer's disease have occurred, since 1971, in kittens infected experimentally with feline leukaemia virus (FeLV). It is suggested that the immunosuppression induced by FeLV may have predisposed the kittens to fatal infections with Bacillus piliformis.Clinical, pathological and ultrastructural features of the disease are described.     

Ocular lesions associated with Trypanosoma evansi in experimentally infected goats

Ocular lesions associated with Trypanosoma spp. infection have been described in man and many animal species. However, loss of vision has not been demonstrated in humans presenting Chagas disease or in animals affected by different trypanosome species. In order to assess the possible ocular disorders caused by Trypanosoma evansi infection, six goats were inoculated with 1 x 10(5) T. evansi and maintained for 12 months and four goats were used as control. The inoculated animals became positive at serological and parasitological tests at 1-month post-inoculation and showed a subclinical course of the disease. Unilateral superficial corneal ulceration and retinochoroiditis were observed in two inoculated animals. Data from ocular neurologic examination and electroretinography showed no significant differences between inoculated and non-inoculated goats. It could be concluded that Trypanosoma evansi can produce ocular lesion but without apparent loss of vision in goats.     

浅谈兔出血症病毒

兔出血症（Rabbit hemorrhagic disease，RHD），又称兔瘟，由兔出血症病毒（Rabbit hemorrhagic disease virus，RHDV）引起的一种急性、高度传染性、高致死性的疾病。以呼吸系统出血，实质器官水肿、淤血及出血变化为特征。1984年，该病首先在我国爆发，随后朝鲜、韩国、意大利、德国、印度、法国、前苏联、西班牙、日本、美国和非洲等国家和地区相继有该病流行的报道。国内外学者从形态学、生物化学和分子生物学对RHDV进行了系统研究。     

Interaction of Marek's disease virus and Cryptosporidium baileyi in experimentally infected chickens

Histocompatible B13/B13 white specific-pathogen-free leghorn chickens were used to investigate the effect of coinfection with Cryptosporidium baileyi and the HPRS 16 strain of Marek's disease virus (MDV) in chickens and to assess the pathogenicity of C. baileyi when MDV is given before or after the parasite. Groups of chickens concurrently infected with C. baileyi orally inoculated at day (D)4 and MDV inoculated at hatching (C4M0 group) or at D8 (C4M8 group) were compared with relevant control groups inoculated with only C. baileyi at D4 (C4 group), only MDV at hatching (M0 group) or at D8 (M8 group), and an uninoculated control group (UC group). The chickens were kept in isolator units until the end of the experiment at D62. Our results showed a considerable synergistic effect in concurrently infected chickens and more severe consequences when chickens received MDV before C. baileyi infection. In fact, except for a slight transitory weakness, the chickens in C4 group remained free of overt clinical signs and there was no mortality. However, coinfection with both pathogens induced more lasting or permanent oocyst shedding. Severe clinical cryptosporidiosis with weakness, anorexia, depression, growth retardation, and chronic and severe respiratory disease causing death occurred in all chickens in the C4M0 group between D12 and D43 and in 67% of the chickens in the C4M8 group between D17 and D57. Eighty-two percent and 33%, respectively, died before the development of specific Marek's disease lesions. Mortality rates were 27% and 33% in the M0 and M8 groups, respectively. The presence of MDV enhanced the establishment of more lasting cryptosporidial infection in the respiratory tract, esophagus, crop, proventriculus, and kidneys (only in C4M0 group) as well as in bursa of Fabricius, ceca, and cloaca. Serologic analysis showed that chickens with chronic cryptosporidiosis in the C4M8 group had an increased level of C. baileyi-specific immunoglobulin A. Our results may explain some cases of mortality in chickens naturally infected with MDV and Cryptosporidium.