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ABSTRACTBovine anaplasmosis is a vector-borne disease that results in substantial economic losses in other parts of the world but so far not in northern Europe. In August 2002, a fatal disease outbreak was reported in a large dairy herd in the Swiss canton of Grisons. Diseased animals experienced fever, anorexia, agalactia, and depression. Anemia, ectoparasite infestation, and, occasionally, hemoglobinuria were observed. To determine the roles of vector-borne pathogens and to characterize the disease, blood samples were collected from all 286 animals: 50% of the cows were anemic. Upon microscopic examination of red blood cells, Anaplasma marginaleinclusion bodies were found in 47% of the cows. The infection was confirmed serologically and by molecular methods. Interestingly, we also found evidence of infections with Anaplasma phagocytophilum, large Babesiaand Theileriaspp., and Mycoplasma wenyonii. The last two species had not previously been described in Switzerland. Anemia was significantly associated with the presence of the infectious agents detected, with the exception of A. phagocytophilum. Remarkably, concurrent infections with up to five infectious vector-borne agents were detected in 90% of the ill animals tested by PCR. We concluded that A. marginalewas the major cause of the hemolytic anemia, while coinfections with other agents exacerbated the disease. This was the first severe disease outbreak associated with concurrent infections with vector-borne pathogens in alpine Switzerland; it was presumably curtailed by culling of the entire herd. It remains to be seen whether similar disease outbreaks will have to be anticipated in northern Europe in the future.

ABSTRACTBoid inclusion body disease (BIBD) is a fatal disorder of boid snakes that is suspected to be caused by a retrovirus. In order to identify this agent, leukocyte cultures (established from Python molurusspecimens with symptoms of BIBD or kept together with such diseased animals) were assessed for reverse transcriptase (RT) activity. Virus from cultures exhibiting high RT activity was banded on sucrose density gradients, and the RT peak fraction was subjected to highly efficient procedures for the identification of unknown particle-associated retroviral RNA. A 7-kb full retroviral sequence was identified, cloned, and sequenced. This virus contained intact open reading frames (ORFs) for gag, pro, pol, and env, as well as another ORF of unknown function within pol. Phylogenetic analysis showed that the virus is distantly related to viruses from both the B and D types and the mammalian C type but cannot be classified. It is present as a highly expressed endogenous retrovirus in all P. molurusindividuals; a closely related, but much less expressed virus was found in all tested Python curtusindividuals. All other boid snakes tested, including Python regius, Python reticulatus, Boa constrictor, Eunectes notaeus, and Morelia spilota, were virus negative, independent of whether they had BIBD or not. Virus isolated from P. moluruscould not be transmitted to the peripheral blood mononuclear cells of B. constrictoror P. regius. Thus, there is no indication that this novel virus, which we propose to name python endogenous retrovirus (PyERV), is causally linked with BIBD.

ABSTRACTHuman immunodeficiency virus infection is characterized by a progressive decline in the number of peripheral blood CD4+T lymphocytes, which finally leads to AIDS. This T-cell decline correlates with the degree of in vitro-induced lymphocyte apoptosis. However, such a correlation has not yet been described in feline AIDS, caused by feline immunodeficiency virus (FIV) infection. We therefore investigated the intensity of in vitro-induced apoptosis in peripheral blood lymphocytes from cats experimentally infected with a Swiss isolate of FIV for 1 year and for 6 years and from a number of long-term FIV-infected cats which were coinfected with feline leukemia virus. Purified peripheral blood lymphocytes were either cultured overnight under nonstimulating conditions or stimulated with phytohemagglutinin and interleukin-2 for 60 h. Under stimulating conditions, the isolates from the infected cats showed significantly higher relative counts of apoptotic cells than did those from noninfected controls (1-year-infected cats, P= 0.01; 6-year-infected cats, P= 0.006). The frequency of in vitro-induced apoptosis was inversely correlated with the CD4+cell count (P= 0.002), bright CD8+cell count (P= 0.009), and CD4/CD8 ratio (P= 0.01) and directly correlated with the percentage of bright major histocompatibility complex class II-positive peripheral blood lymphocytes (P= 0.004). However, we found no correlation between in vitro-induced apoptosis and the viral load in serum samples. Coinfection with feline leukemia virus enhanced the degree of in vitro-induced apoptosis compared with that in FIV monoinfected cats. We concluded that the degree of in vitro-induced apoptosis was closely related to FIV-mediated T-cell depletion and lymphocyte activation and could be used as an additional marker for disease progression in FIV infection.

Background: Safety considerations require that biological products for human use are free from any agent that might pose a potential health hazard. One method to detect the presence of retroviral particles is the reverse transcriptase (RT) assay. This assay is capable of detecting all infectious retrovirus particles, irrespective of genome or protein composition. Recently, a family of ultrasensitive RT tests, named product-enhanced reverse transcriptase (PERT) assays, has been designed with a detection limit that is 10−10 times lower than that of conventional RT tests. Objectives: To investigate with the PERT assay whether RT activity is detectable in live attenuated virus vaccines and to characterize eventual RT activities. Study design: A total of 12 different monovalent and one trivalent virus vaccines containing live attenuated viruses were tested for RT activity with the PERT assay and a conventional RT test. RT activities were investigated with respect to their susceptibility to RT inhibitors, association with physical particles, and their possible origin. Results: One trivalent and five different monovalent vaccines contained RT activity when tested with the PERT assay, but were negative in a conventional RT assay. All lots tested of these vaccines showed RT activity. The activity in all vaccines was sensitive to AZT-triphosphate and ddTTP and at least part of it was associated with particles. Mg -dependent RT activity banded at a density of 1.14 g/ml. All positive vaccines were produced using chicken cells. Conclusions: The data indicate the systematic presence of partially particle-associated retroviral reverse transcriptase in attenuated live virus vaccines that are produced in chicken-derived cells. The identification and further characterization of these particles, as well as the elucidation of possible interactions with the human organism are imperative goals despite the fact that these vaccines have been safely used for many years.