Computed Tomographic and Histopathologic Studies of Lung Function Immediately Post Natum in Canine Neonates.

BACKGROUND: The lung tissue in newborn canine neonates is still in a morphologically and functionally immature, canalicular-saccular stage. True alveoli are only formed postnatally. The aim of this study was to analyze the spatial and temporal development of the ventilation of the lung tissue in vital canine neonates during the first 24 h post natum (p.n.). METHODS: Forty pups (birth weight Ø 424 g ± 80.1 g) from three litters of large dog breeds (>20 kg live weight) were included in the studies. Thirty-three pups (29 vital, 2 vitally depressed, 2 stillborn neonates) originated from controlled, uncomplicated births (n = 3); moreover, six stillborn pups as well as one prematurely deceased pup were birthed by other dams with delivery complications. Computed tomography (CT) was used in 39 neonates, and histopathologic tissue classification techniques (HALO) were used in 11 neonates (eight stillborn and three neonates died early post natum, respectively) to quantify the degree of aerated neonatal lung tissue. RESULTS: It was shown that, in vital born pups, within the first 10 min p.n., the degree of ventilation reached mean values of -530 (±114) Hounsfield units (HU) in the dorsal and -453.3 (±133) HU in the ventral lung area. This is about 75-80% of the final values obtained after 24 h p.n. for dorsal -648.0 (±89.9) HU and ventral quadrants -624.7 (±76.8) HU. The dorsal lung areas were always significantly better ventilated than the ventral regions (p = 0.0013). CT as well as histopathology are suitable to clearly distinguish the nonventilated lungs of stillborns from neonates that were initially alive after surviving neonatal respiratory distress syndrome but who died prematurely (p = 0.0398). CONCLUSION: The results of this study are clinically relevant since the lung tissue of canine neonates presents an aeration profile as early as 10 min after birth and continues progressively, with a special regard to the dorsal lung areas. This is the basis for resuscitation measures that should be performed, preferably with the pup in the abdomen-chest position.

Toxoplasma gondii and Alternaria sp.: An Original Association in an Immunosuppressed Dog with Persistent Skin Lesions.

Dogs and cats may suffer from a variety of diseases, mainly immune mediated, that require the administration of immunosuppressive drugs. Such therapies can cause adverse effects either by the toxicity of the drugs or as a consequence of immune suppression and associated opportunistic infections. Here we present an, yet unknown, association of Toxoplasma gondii and Alternaria fungus, within cutaneous lesions in a dog under long-term immunosuppressive therapy. The diagnosis of such infections is laborious and not obvious at first glance, since the clinical signs of cutaneous toxoplasmosis, neosporosis or alternariosis are not specific. A further laboratory confirmation is needed. Therefore, we currently recommend that dogs and cats should undergo serologic testing for toxoplasmosis or neosporosis prior to immunosuppressive therapy and a regular dermatological evaluation during the immunosuppressive therapy.

A double deletion prevents replication of the pestivirus bovine viral diarrhea virus in the placenta of pregnant heifers.

In contrast to wild type bovine viral diarhea virus (BVDV) specific double deletion mutants are not able to establish persistent infection upon infection of a pregnant heifer. Our data shows that this finding results from a defect in transfer of the virus from the mother animal to the fetus. Pregnant heifers were inoculated with such a double deletion mutant or the parental wild type virus and slaughtered pairwise on days 6, 9, 10 and 13 post infection. Viral RNA was detected via qRT-PCR and RNAscope analyses in maternal tissues for both viruses from day 6 p.i. on. However, the double deletion mutant was not detected in placenta and was only found in samples from animals infected with the wild type virus. Similarly, high levels of wild type viral RNA were present in fetal tissues whereas the genome of the double deletion mutant was not detected supporting the hypothesis of a specific inhibition of mutant virus replication in the placenta. We compared the induction of gene expression upon infection of placenta derived cell lines with wild type and mutant virus via gene array analysis. Genes important for the innate immune response were strongly upregulated by the mutant virus compared to the wild type in caruncle epithelial cells that establish the cell layer on the maternal side at the maternal-fetal interface in the placenta. Also, trophoblasts which can be found on the fetal side of the interface showed significant induction of gene expression upon infection with the mutant virus although with lower complexity. Growth curves recorded in both cell lines revealed a general reduction of virus replication in caruncular epithelial cells compared to the trophoblasts. Compared to the wild type virus this effect was dramtic for the mutant virus that reached only a TCID50 of 1.0 at 72 hours post infection.

Dry-fog decontamination of microbiological safety cabinets after activities with SARS-CoV-2: cycle development and process validation for dry fogging with peroxyacetic acid.

Background: Technical protection measures for laboratory activities involving biological agents include biological safety cabinets (BSC) that may be contaminated. In the case of diagnostic activities with SARS-CoV-2, this may also affect BSC that are operated at protection level 2; therefore, decontamination of all contaminated surfaces of the BSC may be required. In addition to fumigation with hydrogen peroxide (H2O2), dry fogging of H2O2-stabilized peroxyacetic acid (PAA) represents another alternative to fumigation with formalin. However, to prove their efficacy, these alternatives need to be validated for each model of BSC. Methods: The validation study was performed on 4 different BSCs of Class II A2 using the "Mini Dry Fog" system. Results: An aerosol concentration of 0.03% PAA and 0.15% H2O2 during a 30 min exposure was sufficient to inactivate SARS-CoV-2. Effective concentrations of 1.0% PAA and 5% H2O2 were required to decontaminate the custom-prepared biological indicators loaded with spores of G. stearothermophilus and deployed at 9 different positions in the BSC. Commercial spore carriers were easier to inactivate by a factor of 4, which corresponded to a reduction of 106 in all localizations. Conclusions: Dry fogging with PAA is an inexpensive, robust, and highly effective decontamination method for BSCs for enveloped viruses such as SARS-CoV-2. The good material compatibility, lack of a requirement for neutralization, low pH - which increases the range of efficacy compared to H2O2 fumigation - the significantly shorter processing time, and the lower costs argue in favor of this method.

Effects of glyphosate residues and different concentrate feed proportions in dairy cow rations on hepatic gene expression, liver histology and biochemical blood parameters.

Glyphosate (GLY) is worldwide one of the most used active substances in non-selective herbicides. Although livestock might be orally exposed via GLY-contaminated feedstuffs, not much is known about possible hepatotoxic effects of GLY. As hepatic xenobiotic and nutrient metabolism are interlinked, toxic effects of GLY residues might be influenced by hepatic nutrient supply. Therefore, a feeding trial with lactating dairy cows was conducted to investigate effects of GLY-contaminated feedstuffs and different concentrate feed proportions (CFP) in the diets as tool for varying nutrient supply to the liver. For this, 61 German Holstein cows (207 ± 49 days in milk; mean ± standard deviation) were either fed a GLY-contaminated total mixed ration (TMR, GLY groups, mean GLY intake 122.7 µg/kg body weight/day) or control TMR (CON groups, mean GLY intake 1.2 µg/kg body weight/day) for 16 weeks. Additionally, both groups were further split into subgroups fed a lower (LC, 30% on dry matter basis) or higher (HC, 60% on dry matter basis) CFP resulting in groups CONHC (n = 16), CONLC (n = 16), GLYHC (n = 15), GLYLC (n = 14). Blood parameters aspartate aminotransferase, γ-glutamyltransferase, glutamate dehydrogenase, cholesterol, triglyceride, total protein, calcium, phosphorus, acetic acid and urea and histopathological evaluation were not influenced by GLY, whereas all mentioned parameters were at least affected by time, CFP or an interactive manner between time and CFP. Total bilirubin blood concentration was significantly influenced by an interaction between GLY and CFP with temporarily elevated concentrations in GLYHC, whereas the biological relevance remained unclear. Gene expression analysis indicated 167 CFP-responsive genes, while seven genes showed altered expression in GLY groups compared to CON groups. Since expression changes of GLY-responsive genes were low and liver-related blood parameters changed either not at all or only slightly, the tested GLY formulation was considered to have no toxic effects on the liver of dairy cows.

Technical and Anatomical Considerations for Reproducible Inactivation of Large Animal Carcasses by Steam Sterilization.

Introduction: The complete inactivation of infectious tissues of large animal carcasses is one of the most challenging tasks in high-containment facilities. Steam sterilization is a method frequently in use to achieve biological inactivation of liquid and solid waste. Objective: This study aims to highlight parameters most effective in creating reproducible cycles for steam sterilization of pig and calf carcasses. Methods: Two pigs or 1 calf were sterilized by running a liquid cycle (n = 3) at 121°C for at least 120 minutes in a pass-through autoclave. To assess the physical and biological parameters, temperature data loggers and biological indicators (BIs) with spores of Geobacillus stearothermophilus (ATCC 7953) were placed at defined positions within animal carcasses. After completion of each cycle, data loggers were analyzed and BIs were incubated for 7 days at 60°C. Results: Initial testing with an undissected pig carcass resulted in suboptimal temperatures at the tissue level with growth on 1 BI. After modifications of the used stainless-steel boxes and by placing the reference probe of the autoclave in the animal carcass, reproducible cycles could be created. A complete inactivation of BIs and a temperature profile of >121°C for at least 20 minutes could be achieved in almost all probed tissues. Conclusion: Only minor modifications in carcass preparation and the used sterilization equipment resulted in effective and reproducible cycles to inactivate large animal carcasses by using a steam autoclave.

Comparative Pathology of Pseudorabies in Different Naturally and Experimentally Infected Species-A Review.

The pseudorabies virus (PRV) is an alphaherpesvirus and the causative agent of Aujeszky's disease (AD). PRV infects a wide range of animal species including swine as the natural host as well as ruminants, carnivores, rodents and lagomorphs. In these species, except for the pig, PRV infection causes acute, severe disease, characterized by insatiable itching, and is always lethal. Horses, chickens and non-human primates have been shown to be largely resistant to PRV infection, while disease in humans is still controversial. PRV is a pantropic virus, which preferably invades neural tissue, but also infects epithelia of various organs, whereupon multisystemic lesions may result. Although AD is mainly associated with severe pruritus, also known as "mad itch", there are notable differences regarding infection route, clinical signs, viral distribution and lesion patterns in different animal species. In this comprehensive review, we will present clinico-pathologic findings from different species, which have been either shown to be susceptible to PRV infection or have been tested experimentally.

Peste Des Petits Ruminants Virus and Goatpox Virus Co-Infection in Goats.

Infection of small ruminants with peste des petits ruminants virus (PPRV) and goatpox virus (GTPV) are endemic and can have devastating economic consequences in Asia and Africa. Co-infection with these viruses have recently been reported in goats and sheep in Nigeria. In this study, we evaluated samples from the lips of a red Sokoto goat, and describe co-infection of keratinocytes with PPRV and GTPV using histopathology and transmission electron microscopy. Eosinophilic cytoplasmic inclusion bodies were identified histologically, and ultrastructural analysis revealed numerous large cytoplasmic viral factories containing poxvirus particles and varying sizes of smaller cytoplasmic inclusions composed of PPRV nucleocapsids. These histopathological and ultrastructural findings show concurrent infection with the 2 viruses for the first time as well as the detection of PPRV particles in epithelial cells of the mucocutaneous junction of the lip.

Estimating the Postmortem Interval of Wild Boar Carcasses.

Knowledge on the postmortem interval (PMI) of wild boar (Sus scrofa) carcasses is crucial in the event of an outbreak of African swine fever in a wild boar population. Therefore, a thorough understanding of the decomposition process of this species in different microhabitats is necessary. We describe the decomposition process of carcasses exposed in cages. Trial 1 compared a wild boar and a domestic pig (Sus scrofa domesticus) under similar conditions; Trial 2 was performed with three wild boar piglets in the sunlight, shade, or in a wallow, and Trial 3 with two adult wild boar in the sun or shade. The wild boar decomposed more slowly than the domestic pig, which shows that standards derived from forensic studies on domestic pigs are not directly applicable to wild boar. The carcasses exposed to the sun decomposed faster than those in the shade did, and the decomposition of the carcass in the wallow took longest. To assess the state of decomposition, we adapted an existing total body scoring system originally developed for humans. Based on our studies, we propose a checklist tailored to wild boar carcasses found in the field that includes the most important information for a reliable PMI estimation.

Characterization of Simbu serogroup virus infections in type I interferon receptor knock-out mice.

In late 2011, Schmallenberg virus (SBV), a novel, arthropod-borne, teratogenic orthobunyavirus, emerged near the German/Dutch border and thereafter spread rapidly throughout the continent thereby causing great economic losses in European livestock. SBV mainly infects ruminants and closely related viruses such as Sabo virus (SABOV), Simbu virus (SIMBUV) and Sathuperi virus (SATV) have been isolated from their insect-vectors or putative ruminant hosts. However, information about their pathogenesis and in vivo studies with SABOV, SIMBUV, and SATV are scarce. As experimental infections of ruminants are comprehensive and time-consuming, an SBV small animal model was assessed regarding its suitability for studying Simbu viruses. Adult type I interferon deficient mice (IFNAR-/-) were subcutaneously infected with the Simbu serogroup members SABOV, SIMV and SATV, respectively, and compared to SBV-infected mice. All animals were clinically, virologically, serologically, and pathologically examined. The clinical signs were mainly characterised by the loss of body weight and by paralysis. In blood, and samples from the spleen and brain, high loads of viral genome were detected using newly developed real-time PCR assays. The most common histologic lesions included meningo-encephalomyelitis, perivascular cuffing of lymphocytes and macrophages, neuronal degeneration and gliosis. These lesions have also been described in foetuses after transplacental infection with SBV. In-situ hybridisation signals were widely distributed in multiple neurons of the brain and spinal cord in all examined, inoculated mice. In conclusion, IFNAR-/- mice are a suitable animal model for pathogenesis studies of a broad range of Simbu serogroup viruses since all the viruses examined displayed a common pattern of viral organ and tissue distribution in this mouse model.

Comparative analysis of European bat lyssavirus 1 pathogenicity in the mouse model.

European bat lyssavirus 1 is responsible for most bat rabies cases in Europe. Although EBLV-1 isolates display a high degree of sequence identity, different sublineages exist. In individual isolates various insertions and deletions have been identified, with unknown impact on viral replication and pathogenicity. In order to assess whether different genetic features of EBLV-1 isolates correlate with phenotypic changes, different EBLV-1 variants were compared for pathogenicity in the mouse model. Groups of three mice were infected intracranially (i.c.) with 102 TCID50/ml and groups of six mice were infected intramuscularly (i.m.) with 105 TCID50/ml and 102 TCID50/ml as well as intranasally (i.n.) with 102 TCID50/ml. Significant differences in survival following i.m. inoculation with low doses as well as i.n. inoculation were observed. Also, striking variations in incubation periods following i.c. inoculation and i.m. inoculation with high doses were seen. Hereby, the clinical picture differed between general symptoms, spasms and aggressiveness depending on the inoculation route. Immunohistochemistry of mouse brains showed that the virus distribution in the brain depended on the inoculation route. In conclusion, different EBLV-1 isolates differ in pathogenicity indicating variation which is not reflected in studies of single isolates.

Chlamydiaceae and Chlamydia-like organisms in free-living small mammals in Europe and Afghanistan.

Few data are available on the occurrence of chlamydial infections in wild small mammals. We investigated the significance of free-living small mammals as reservoirs or transmission hosts for microorganisms of the phylum/class Chlamydiae. We obtained 3,664 tissue samples from 911 animals in Switzerland, Germany, Austria, the Czech Republic, and Afghanistan. Samples included internal organs (n = 3,652) and feces (n = 12) from 679 rodents (order Rodentia) and 232 insectivores (order Soricomorpha) and were tested by three TaqMan® real-time PCRs specific for members of the family Chlamydiaceae and selected Chlamydia-like organisms such as Parachlamydia spp. and Waddlia spp. Only one of 911 (0.11%) animals exhibited a questionable positive result by Chlamydiaceae-specific real-time PCR. Five of 911 animals were positive by specific real-time PCR for Parachlamydia spp. but could not be confirmed by quantitative PCR targeting the Parachlamydia acanthamoebae secY gene (secY qPCR). One of 746 animals (0.13%) was positive by real-time PCR for Waddlia chondrophila. This result was confirmed by Waddlia secY qPCR. This is the first detection of Chlamydia-like organisms in small wildlife in Switzerland. Considering previous negative results for Chlamydiaceae in wild ruminant species from Switzerland, these data suggest that wild small mammals are unlikely to be important carriers or transport hosts for Chamydiaceae and Chlamydia-like organisms.

Oral squamous cell carcinoma in a red deer (Cervus elaphus).

We describe the pathomorphologic and immunophenotypic characteristics of an oral squamous cell carcinoma in a 13-yr-old, free-ranging red deer (Cervus elaphus) in Lower Saxony, Germany.

Chimeric rabies viruses for trans-species comparison of lyssavirus glycoprotein ectodomain functions in virus replication and pathogenesis.

The glycoprotein G of lyssaviruses is the major determinant of virus pathogenicity and serves as a target for immunological responses to virus infections. However, assessment of the exact contribution of lyssavirus G proteins to observed differences in the pathogenicity of lyssavirus species is challenging, since the direct comparison of natural lyssaviruses does not allow specific ascription to individual virus proteins or domains. Here we describe the generation and characterization of recombinant rabies viruses (RABV) that express chimeric G proteins comprising of a RABV cytoplasma domain fused to transmembrane and ectodomain G sequences of a virulent RABV (challenge virus standard; CVS-11) or two European bat lyssaviruses (EBLV- and EBLV-2). These "envelope-switched" recombinant viruses were recovered from cDNAs. Similar growth kinetics and protein expression in neuroblastoma cell cultures and successful targeting of primary neurons showed that the chimeric G proteins were able to replace the authentic G protein in a RABV based virus vector. Inoculation of six week old CD-1 mice by the intracranial (i. c.) route of infection further demonstrated that all recombinant viruses were able to spread in the brain and to induce disease. The "envelope-switched" RABV therefore represent an important tool to further investigate the influence of lyssavirus ectodomains on virus tropism, and pathogenicity.

Preclinical analysis of treosulfan in combination with total body irradiation as conditioning regimen prior to bone marrow transplantation in rats.

Treosulfan (Treo) and total body irradiation (TBI) demonstrate a high therapeutic activity in treatment of acute leukemia and lymphoma. We investigated the combination of Treo and TBI prior to bone marrow transplantation (BMT) in rats. Female Lewis rats were treated with Treo on 3 consecutive days followed by TBI with either 5 Gy (n = 28) or 7.5 Gy (n = 48). After conditioning animals received 4 x 10E7 bone marrow cells (BC) from female Lewis rats. Additional 16 rats were transplanted with 4 x 10E7 BC and 1.5 x 10E7 spleen T-cells from female Brown-Norway (BN) rats. Animals were examined daily for clinical signs and toxicity was investigated by necropsy and histology in all animals. Gastrointestinal toxicity was the dose-limiting factor of Treo in combination with TBI. The highest tolerable dose of Treo in combination with 7.5 Gy TBI was 3 x 0.5 g/kg and the highest tolerable dose of Treo in combination with 5 Gy TBI was 3 x 0.6 g/kg. Allogeneic BMT from BN donors resulted in engraftment and survival of 12 out of 16 animals. Gastrointestinal toxicity is the dose-limiting factor in the treatment with Treo and TBI. Furthermore, Treo possesses certain characteristics of a radiosensitizer.

Nevus lipomatosus cutaneus superficialis (Hoffmann-Zurhelle) in a chimpanzee (Pan troglodytes).

BACKGROUND: A 32-year-old, male chimpanzee (Pan troglodytes) kept in a zoo developed a focally extensive, proliferative, cerebriform, dermal mass at the left inner thigh extending to the inguinal region. After surgical removal, the mass recurred and extended progressively over a period of 5 years. METHODS AND RESULTS: At necropsy, a 20 x 20 cm large, well defined, papular and partly verrucous, rubbery mass composed of multiple large, soft nodules measuring up to 4 cm in diameter was observed in the left thigh and inguinal region. Histological examination revealed a multifocal expansion of the dermis by mature adipocytes that were arranged in small islands to large lobular aggregates. Dermal proliferations of adipocytes were almost completely separated from the subcutaneous adipose tissue. CONCLUSIONS: This is the first report of a unique lesion that resembles human Nevus lipomatosus cutaneus superficialis in a chimpanzee and is different from lipoma or liposarcoma.

Evaluation of baculovirus-derived recombinant 53-kDa protein of Trichinella spiralis for detection of Trichinella-specific antibodies in domestic pigs by ELISA.

The complete gene encoding the 53-kDa protein derived from Trichinella spiralis was cloned and expressed using a baculovirus-based system. Characterization of a purified fusion protein consisting of the 53-kDa protein and the glutathione S-transferase protein showed unspecific reactivity with swine pre-immune serum in both enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. Subsequently, a purified C-terminal 6xHis-tagged 53-kDa protein was used in an ELISA. The evaluation of the test using a negative serum panel showed a high specificity for the ELISA. Serum panels of pigs infected with T. spiralis of two independent experiments showed that pigs of one experiment were tested positive by the ELISA, whereas all sera of the second experiment were negative, indicating a low sensitivity of the ELISA. Furthermore, experimental evidence was found by using mass spectroscopy and Western blot analysis that the 53-kDa protein was not part of the excretory/secretory antigen of T. spiralis as shown in this study.

Granulomatous inflammation of salt glands in ducklings (Anas platyrhynchos) associated with intralesional Gram-negative bacteria.

The "nasal glands" occur in many bird species and are powerful sodium ion-excretory organs. In ducks, they are located in supraorbital bony recesses. Granulomatous inflammation of these glands occurs with an incidence of approximately 1% in ducklings (Anas platyrhynchos), and is not associated with specific clinical symptoms. We investigated nine glands of eight animals with granulomas by gross pathology and histopathology, and compared results of bacteriology with 20 non-lesioned nasal glands. Adenitis was characterized by multifocal to coalescent heterophilic granulomas with central necrotic heterophils, and multinucleate giant cells, lymphocytes and plasma cells. Within the centres of the granulomas, there were clusters of Gram-negative bacteria that were identified as halo-tolerant Pseudomonas aeruginosa, Proteus mirabilis and Aeromonas hydrophila. Normal glands contained exclusively various halo-tolerant Gram-positive bacteria, mostly Streptococcus sp. and Enterococcus sp. The distribution of lesions and lack of clinical symptoms were suggestive of a localized ascending infection via the secretory ductules.

Recombinant virus-expressed bovine cytokines do not improve efficacy of a bovine herpesvirus 1 marker vaccine strain.

Cytokines play a key role as regulators of the immune response. To elucidate whether the efficacy of a live virus vaccine can be improved by co-expression of cytokines, expression cassettes for bovine interleukins (boIL)-2, -4, -6, and -12 and bovine interferon-gamma (boIFN-gamma) were integrated into the glycoprotein E (gE)-locus of the bovine herpesvirus 1 (BHV-1) vaccine virus strain GK/D. Cell culture analyses demonstrated that expression of the cytokines did not impair the replication of the recombinant viruses. To test safety and efficacy, groups of 4-6 months old BHV-1 seronegative calves were vaccinated intranasally with the parental virus strain GK/D or the recombinants, and challenged intranasally 3 weeks later with virulent BHV-1. The animals were monitored for clinical signs, virus excretion and antibody status after vaccination and challenge. All vaccines were well tolerated and protected the immunised calves from clinical disease following challenge, and reduced duration and titres of challenge virus shedding. Calves inoculated with the boIL-6, boIL-12 and boIFN-gamma expressing recombinants showed a significant reduction in vaccine virus shedding but secreted more challenge virus than the other vaccinees. These findings indicate that expression of these cytokines mediates a better control of the vaccine virus replication which, however, interferes with the immunogenicity of the vaccine. In summary, all recombinant viruses were safe and effective, but protection afforded by the recombinants was not improved as compared to vaccination with the parental virus strain GK/D.

Lack of TNF alpha supports persistence of a plasmid encoding the bovine leukaemia virus in TNF(-/-) mice.

Tumour necrosis factor (TNF) is well recognised for its role in mediating innate immune responses. However, the mechanisms of TNF that influence the adaptive immune response to viral infections are poorly understood. Over recent years, there has been evidence to suggest a role for TNF in the early phase of infection of ruminants with bovine leukaemia virus (BLV). In this study, we infected TNF(-/-) mice with a plasmid encoding infectious BLV to further elucidate the role of TNF in BLV infection. TaqMan quantitative PCR showed that proviral DNA was present in genomic DNA isolated from spleen cells of TNF(-/-) mice 4 weeks post-infection, whereas it was not detected in wild-type mice. We were not able to detect differences in serum IgM or IgG levels between the TNF(-/-) and wild-type mice, or antibodies to BLV after this short period. In showing that the lack of TNF enables the plasmid encoded BLV to persist longer, and therefore rendering the mice more susceptible to an infection with BLV, the data suggest an important defence function of TNF in the early phase of BLV infection.