Enterocytozoon bieneusi in Bovine Viral Diarrhea Virus (BVDV) infected and noninfected cattle herds.

Enterocytozoon bieneusi known as a causative agent of opportunistic infections instigating diarrhoea in AIDS patients was identified also in a number of immunocompetent patients and in a wide range of animals, including cattle. In the present study we tested if the Bovine Viral Diarrhea Virus (BVDV), the most common pathogen underlying immunosuppressive Bovine Viral Diarrhoea (BVD), can enhance the occurrence of opportunistic infections with E. bieneusi in cattle. Six dairy farms were investigated using ELISA to detect antibodies against or antigens arising from BVDV in collected sera. A total of 240 individual faecal samples from four age groups were examined for the presence of E. bieneusi by nested PCR. Sequence analysis of six E. bieneusi positive samples revealed the presence of the genotype I of E. bieneusi, previously described in cattle. The hypothesis expecting higher prevalence of E. bieneusi in BVDV positive cattle herds was not confirmed in this study; however this is the first description about E. bieneusi in cattle in the Czech Republic.

Experimental oral and ocular Encephalitozoon cuniculi infection in rabbits.

Encephalitozoon cuniculi is an obligate intracellular pathogen that has a wide host distribution, but primarily affects rabbits. The aim of this study was to characterize both the cell-mediated and the antibody response in rabbits after experimental infection using 2 different infection routes: oral and ocular. SPF rabbits were infected with low (10³ spores) and high (107 spores) infection doses. Monitored parameters included clinical signs, detection of spores in urine, antibody response detected with ELISA, and cell-mediated immunity detected by antigen-driven lymphocyte proliferation. At week 13 post-infection, half of the rabbits in each group were suppressed by intramuscular administration of dexamethasone. At week 18 post-infection, animals were euthanized. Clinical signs were mild with exacerbation after immunosuppression. Spores in urine and antigen-specific cell-mediated immunity were detected from weeks 5 and 4 post-infection, respectively. Specific IgM was detected 1 week after infection, and IgG antibodies followed 1 week later in rabbits infected with the high dose. Immunological responses were dose dependent. The authors can conclude that both oral and ocular experimental infection with E. cuniculi resulted in an immune response of the infected animals. Rabbits could be used as an experimental model for the study of ocular microsporidiosis.

Restriction enzyme analysis of RT-PCR amplicons as a rapid method for detection of genetic diversity among bovine respiratory syncytial virus isolates.

Our current knowledge of antigenic variability of the bovine respiratory syncytial virus (BRSV) is quite limited and is mainly dependent on the use of monoclonal antibodies (mAb). In this study, we present not only analysis of the antigenic, but also of the genetic variability of BRSV. Using a panel of BRSV-specific mAb we distinguished five main reactivity patterns, three of which corresponded to the previously established subgroups A, B and AB. A single viral strain yielded the fourth pattern, while four viral strains did not react with any of the used mAbs forming the fifth pattern. To investigate the genetic basis for the antigenic heterogeneity of the BRS virus G protein, DNA of 11 BRSV isolates was directly sequenced. The comparison of the obtained nucleotide or amino acid sequences to those BRSV strains present in the GenBank revealed 88.1-99.4% and 77.7-98.4% similarity, respectively. These results supported the previously stated suggestion to type BRSV isolates according to their genetic relationship. In order to introduce a rapid and simple method to study the genetic variability of BRSV, we utilized the restriction enzyme analysis of RT-PCR products derived from mRNAs corresponding to the most variable region of the BRSV glycoprotein G ectodomain. Using this restriction enzyme analysis we were able to identify genetic variability among BRSV isolates. The detected non-synonymous mutations led frequently to a change in digestion pattern and were predominantly located in two mucin-like regions of the G protein gene. A correlation has been found between grouping of isolates in the phylogenetic tree and their restriction patterns clustering together isolates with the same restriction profiles. However, viruses placed distant in the tree sharing the same restriction patterns were detected supposing that phylogenetic analysis should be necessary for BRSV typing. Thus, we propose to use DNA restriction polymorphism for a rapid detection of genetic variants among BRSV isolates circulating in cattle population and as a preliminary tool for their typing.

Bovine respiratory syncytial virus strains currently circulating in the Czech Republic are most closely related to Danish strains from 1995.

In this study we showed a high degree of genetic homogeneity among recently (2002-2003) circulating Bovine respiratory syncytial virus (BRSV) strains in cattle population in the Czech Republic. These strains are in a phylogenetic tree more closely related to the Danish strains from 1995 than to the Czech strain VS97 from 1997 that shares the highest similarity with the French strain F1 and the Belgian strain P10. From the sequence analysis we deduce that the revealed high diversity between BRSV strains from 2002-2003 and those from 1997, at both nucleotide (0-11.4%) and amino acid (0-21%) level, is more likely due to distinct sources of the virus strains than to the sequence evolution.

Demonstration of bovine respiratory syncytial virus RNA in peripheral blood leukocytes of naturally infected cattle.

RNA of Bovine respiratory syncytial virus (BRSV) was found in peripheral leukocytes and nasal mucosa of infected cows by nested reverse transcription-polymerase chain reaction (nRT-PCR). We suppose that this finding obtained in the convalescent phase of infection indicates possible persistence of the virus in cells of the immune system.

[Respiratory syncytial viruses: viral characteristics and epizootiology of the disease]. / Respiracní syncytiální virus: vlastnosti viru a epizootologie onemocnení.

Human respiratory syncytial virus (HRSV) is the major respiratory tract pathogen of infants and young children. Bovine respiratory syncytial virus (BRSV) is recognized as an important cause of respiratory tract disease in calves. Both these viruses and their respective diseases share many similarities. After a description of the general properties of the virus, this review covers the epizootology of bovine respiratory syncytial virus infection.

[Respiratory syncytial viruses: pathogenesis, immunology and disease prevention]. / Respiracní syncytiální virus: patogeneze, imunologie a profylaxe onemocnení.

Immunopathologic mechanism has been proposed to be involved in the pathogenesis of respiratory syncytial virus infections. This review examines the current understanding of the role of immunopathologic mechanisms in RSV infections. The role of vaccines in inducing hypersensitivity is also discussed.