Histo-Blood Group Antigens Act as Attachment Factors of Rabbit Hemorrhagic Disease Virus Infection in a Virus Strain-Dependent Manner

Rabbit Hemorrhagic disease virus (RHDV), a calicivirus of the Lagovirus genus, and responsible for rabbit hemorrhagic disease (RHD), kills rabbits between 48 to 72 hours post infection with mortality rates as high as 50–90%. Caliciviruses, including noroviruses and RHDV, have been shown to bind histo-blood group antigens (HBGA) and human non-secretor individuals lacking ABH antigens in epithelia have been found to be resistant to norovirus infection. RHDV virus-like particles have previously been shown to bind the H type 2 and A antigens. In this study we present a comprehensive assessment of the strain-specific binding patterns of different RHDV isolates to HBGAs. We characterized the HBGA expression in the duodenum of wild and domestic rabbits by mass spectrometry and relative quantification of A, B and H type 2 expression. A detailed binding analysis of a range of RHDV strains, to synthetic sugars and human red blood cells, as well as to rabbit duodenum, a likely gastrointestinal site for viral entrance was performed. Enzymatic cleavage of HBGA epitopes confirmed binding specificity. Binding was observed to blood group B, A and H type 2 epitopes in a strain-dependent manner with slight differences in specificity for A, B or H epitopes allowing RHDV strains to preferentially recognize different subgroups of animals. Strains related to the earliest described RHDV outbreak were not able to bind A, whereas all other genotypes have acquired A binding. In an experimental infection study, rabbits lacking the correct HBGA ligands were resistant to lethal RHDV infection at low challenge doses. Similarly, survivors of outbreaks in wild populations showed increased frequency of weak binding phenotypes, indicating selection for host resistance depending on the strain circulating in the population. HBGAs thus act as attachment factors facilitating infection, while their polymorphism of expression could contribute to generate genetic resistance to RHDV at the population level

Cytometric analysis of lymphocytes T and B in rabbits infected with non-haemagglutinogenic strains of RHD virus [rabbit heamorrhagic disease] - Rainham, Frankfurt and Asturias

The present paper refers to the cytometric analysis of lymphocytes T (with receptor CD5+), Th (with receptor CD4+), Tc/Ts (with receptor CD8+), lymphocytes CD25+ and lymphocytes B with receptor CD19+ in rabbits experimentally infected with strains of RHD virus - Rainham, Frankfurt and Asturias, not having haemagglutinogenic capacities, which makes them unique, as haemagglutinogenic capacity is a classic and typical property of most strains of this virus. The study was performed in the dynamic system, drawing blood samples from animals at hour 0, namely before the administration of the viral antigen, and then at 4, 8, 12, 24 and 36 h after the infection. The study indicated that Rainham and Asturias strains of RHD virus cause a similar amount of changes as the most immunogenic haemagglutinogenic strains CAMP V-561 and CAMP V-562 of the RHD virus do. In contrast, the Frankfurt strain of the RHD virus is characterised with 5-6-fold lower reactivity in this respect and is most similar to the least immunogenic haemagglutinogenic strain CAMP V-558 of the RHD virus

Lymphocyte subpopulations and apoptosis of immune cells in rabbits experimentally infected with a strain of the RHD virus having a variable haemagglutination capacity

The paper describes the immunological response in the matter of percentage of T cells (receptor CD5+) and subpopulations (Th with receptor CD4+, Tc/Ts with receptor CD8+, T with receptor CD25+) and B cells with receptor CD19+, as well as the percentage of apoptotic granulocytes and lymphocytes, in rabbits experimentally infected with the Hagenow strain of the RHD virus. The material chosen for the experiment is special, as among all strains of RHD virus, there are only two strains which carry the variable haemagglutination capacity of red cells. The results of the study show that the Hagenow strain gives an untypical picture of T and B lymphocytes, whereas the results in inducing apoptosis seems to corespond with previous data, confirming the inclusion of apoptosis from 4 h p.i. and the intensity of the phenomenon being higher in granulocytes

Phagocytosis of neutrophils in rabbits infected with antigenic variants of RHD (rabbit haemorrhagic disease) virus

The present study was aimed at determining changes in chosen elements of phagocytosis in rabbits infected with 3 antigenic variants of RHD – Hartmannsdorf, Pv97 and 9905, which differed in haemagglutination ability. The animals were tested for phagocytosis parameters, and the results revealed that the examined strains showed the differences. These variations regarded mainly Pv97 strain, as the intensity of the changes were 5 times stronger in comparison to strain Hartmannsdorf and 9905. As all of the strains examined are signified as antigenic variants, we have stated that this feature does not determine their immunological picture. The results suggest the existence of immunological dissimilarities among strains of the RHD virus, which was revealed for the first time in antigenic variants

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

Apoptosis of granulocytes and lymphocytes in peripheral blood in rabbits infected with haemagglutinating and non-haemagglutinating antigenic variants of the RHD (rabbit haemorrhagic disease) virus

This paper attempts to study the dynamics of apoptosis of granulocytes and lymphocytes in peripheral blood in rabbits infected with haemagglutinating (Vt97, Triptis, Hartmannsdorf) and non-haemagglutinating (Pv97, 9905 RHDVa) antigenic variants of the RHD virus. The pathogenicity of those antigenic variants was also assessed by recording the mortality of the infected animals. The animals were infected with antigenic variants and blood was sampled at hour 0,4,8,12,24,36 p.i. and the percentage of apoptotic granulocytes and lymphocytes was measured with the use of flow cytometry. The results of the study showed that apoptosis is included during RHDV infection, as the number of apoptotic granulocytes and lymphocytes increases throughout the experiment; depending on the antigenic variant, apoptosis joins in at 4-8-12 h p.i. and lasts until 24-36 h p.i. Furthermore, the mortality of rabbits infected with the examined strains of RHD virus varied from 30% to 100%. This study performed for the first time in this manner, indicates the importance of apoptosis during infection with the RHD virus

Lymphocytes T and B in rabbits infected with RHD virus

The aim of this study was to determine the differences in immunological response of animals infected with different antigenic variants of the virus – three haemagglutinating (Vt97, Triptis, Hartmannsdorf) and two non-haemagglutinating (Pv97, 9905 RHDVa). The specific immunological response was measured by the dynamics of changes in the amount of lymphocytes T (with CD5+, CD4+, CD8+, CD25+ receptor) and B (with CD19+ receptor). The study showed differences in immunogenicity of the analysed RHDV antigenic variants, which allowed them to be divided into groups of: more immunogenic strains, including non-haemagglutinating 9905 RHDVa and haemagglutinating Vt97 and Triptis variants; and less immunogenic strains, including the haemagglutinating Hartmannsdorf variant and the non-haemagglutinating Pv97 variant. Such a result may indicate that the agglutination capacity of red blood cells might not be a factor impacting the number of T and B lymphocytes

Autophagy in physiological and pathological processes - selected aspects

This paper describes a model of cell death, called autophagy, one among other typical and atypical processes of cell death. This phenomenon is present in the organism, from conception until death, and is conditioned by many genes of ATG family, or mTOR kinase and specific proteins, like BNIP3. This process plays a very important role not only in physiological functions of the organism but also in pathological, such as Alzheimer or Huntington disease, as well as diseases caused by viruses

Real time PCR detection of rabbit haemorrhagic disease virus in rabbits infected with different European strains of RHDV

The paper concerns the use of a novel, very effective diagnostic method, a real-time PCR for diagnosis of a viral agent causing viral haemorrhagic disease in rabbits – RHDV. Until now, the method was widely used for detecting many different viruses, both DNA, and RNA, but as far as RHDV is concerned, there are not many records of such use. This study aimed at the detection of 17 different strains from different European regions, differing in biological features and mortality. The study confirmed that real-time PCR is an applicable and effective method for diagnosis of RHDV, irrespective of the stains’ features

B-cell and T-cell values in peripheral blood in Polish mixed-breed rabbits with addition of blood of meet breeds

In Poland, rabbit is a highly valued animal, due to dietetic and flavour values of its meat, but above all, rabbits tend to be commonly used laboratory animals. The aim of the study was developing standards for counts of B-cells with CD19+ receptor, T-cells with CD5+ receptor, and their subpopulations, namely T-cells with CD4+, CD8+ and CD25+ receptor in the peripheral blood of mixed-breed Polish rabbits with addition of blood of meet breeds, including the assessment of the impact of four seasons of the year and animal sex on the values of the immunological parameters determined. The results showed that the counts of B- and T-cells and their subpopulations in peripheral blood remain within the following ranges: for CD19+ B-cells: 1.05 - 3.05%, for CD5+ T-cells: 34.00 - 43.07%, CD4+ T-cells: 23.52 - 33.23%, CD8+ T-cells: 12.55 - 17.30%, whereas for CD25+ T-cells: 0.72 - 2.81%. As it comes to the season of the year, it was observed that it principally affects the values of CD25+ T-cells, while in the case of rabbit sex, more changes were found in females