Papers by Thomas Vahlenkamp
Clinical and Vaccine Immunology, 2014
![Research paper thumbnail of [Detection of bovine leukaemia virus (BLV) in tissue samples of naturally and experimentally infected cattle]](https://a.academia-assets.com/images/blank-paper.jpg)
[Detection of bovine leukaemia virus (BLV) in tissue samples of naturally and experimentally infected cattle]
Berliner Und Munchener Tierarztliche Wochenschrift, 2008
Enzootic bovine leukaemia (EBL) which is caused by the bovine leukaemia virus (BLV) still plays a... more Enzootic bovine leukaemia (EBL) which is caused by the bovine leukaemia virus (BLV) still plays a remarkable role despite a significant success in sanitation programmes. In the Federal Republic of Germany it was not possible to eradicate the disease until today. Sporadically during slaughter or necropsy of cattle neoplastic lesions of the lymphatic tissues are observed that need to be clarified with regard to BLV as etiological agent. Due to the fact that in most instances no serological data are available from the respective animals and blood drawings from the original holdings are not easy to obtain the polymerase chain reaction (PCR) opens new avenues as supplementary diagnostic tool to test unfixed lymphatic tissues for the presence of BLV proviral DNA. Lymph node tissues from 10 naturally or experimentally BLV-infected cattle, which have been monitored virologically and serologically, and tissues from 4 negative animals were processed, DNA was extracted and subjected to PCR to amplify BLV env gene specific sequences. The results show that in cattle with BLV-induced leukosis as well as in cattle, which were clinically healthy and unsuspicious at slaughter or at post-mortem, either with persistent lymphocytosis (PL) or without, BLV proviral DNA could be detected easily in samples of lymphatic tissues and in high concordance with serological data. In this article data from the National and OIE reference laboratory for EBL at the Friedrich-Loeffler-Institut (FLI, Germany) are presented. Elaborated laboratory protocols for processing of tissue samples and performing of BLV-PCR are recommended.
The Journal of general virology, 1999
The envelope is of cardinal importance for the entry of feline immunodeficiency virus (FIV) into ... more The envelope is of cardinal importance for the entry of feline immunodeficiency virus (FIV) into its host cells, which consist of cells of the immune system including macrophages. To characterize the envelope glycoprotein determinants involved in macrophage tropism, chimeric infectious molecular clones were constructed containing envelope gene sequences from isolates that had been propagated in peripheral blood mononuclear cells (PBMC). The progeny virus was examined for growth in PBMC and bone marrow-derived macrophages and viruses with different replication kinetics in macrophages were selected. Envelope-chimeric viruses revealed that nucleotide sequences encoding variable regions 3 and 4 of the surface glycoprotein, SU, are involved in macrophage tropism of FIV. To assess the biological importance of this finding, the phenotypes of envelope proteins of viruses derived from bone marrow, brain, lymph node and PBMC of an experimentally FIV-infected, healthy cat were examined. Since ...
[Quantification of feline immunodeficiency virus (FIV) RNA in the plasma of infected cats]
Berliner und Münchener tierärztliche Wochenschrift, 1996
A competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to quantify RNA o... more A competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to quantify RNA of feline immunodeficiency virus (FIV) in cats. The assay uses in vitro synthesized RNA as a competitive internal control. The synthesized RNA has a 22-base deletion with respect to the wild-type sequence. PCR products were quantitated by densitometric analysis of a digitized image of the ethidium bromide stained gel. Viral RNA concentrations in the plasma of two cats experimentally infected with FIV strain UT113 were followed for 32 weeks; peak copy numbers (2.3 x 10(4) and 1.3 x 10(4) per ml, respectively) were reached 11 weeks after subcutaneous injection of ten 50% cat infectious doses. With rising antibody titers against FIV-gag and FIV-env gene products, the amount of FIV RNA in plasma decreased. Nine asymptomatic cats that had been experimentally infected 3.5 to 4.5 years earlier had copy numbers between 5.6 x 10(3) and 4.3 x 10(4) per ml. Cats treated for six weeks with 9-(2-phosp...
Increased mitochondrial superoxide dismutase expression and lowered production of reactive oxygen species during rotavirus infection
Virology, 2010
Rotaviruses are responsible for severe diarrhea in infants and substantial economic losses in ani... more Rotaviruses are responsible for severe diarrhea in infants and substantial economic losses in animal husbandry worldwide. We investigated the oxidant/antioxidant status in rotavirus-infected human colon adenocarcinoma (Caco-2) cell line. Our results show that within the initial 48 h of infection the expression of the mitochondrial superoxide dismutase (MnSOD) is significantly increased, which correlates with a decrease in reactive oxygen species production, and with a lack of cellular glutathione depletion. During this period the mitochondria display a hyperpolarization of the inner membrane, which leads to an increased mitochondrial membrane potential. No increase in apoptosis was detected in the infected cultures. In contrast to many viral infections which cause redox imbalance in host cells, the described virus-host interaction suggests that rotavirus infection does not lead to an induction of oxidative stress, possibly to prolong cell survival and to allow for accumulation of viral particles before cell destruction and virus release.
Veterinary Immunology and Immunopathology, 2009
Veterinary Immunology and Immunopathology, 2010
Journal of Veterinary Diagnostic Investigation, 2012
Bovine leukemia virus (BLV) causes a persistent infection with provirus formation in B-lymphocyte... more Bovine leukemia virus (BLV) causes a persistent infection with provirus formation in B-lymphocytes. A realtime polymerase chain reaction (PCR) based on the conserved BLV polymerase (BLV pol) gene sequences was developed. Dually labeled probes were used to permit detection by the 5′ exonuclease assay. The assay was validated with 350 samples of bovine peripheral blood mononuclear cells including 144 samples from BLV-seropositive animals worldwide (South America, Europe, Middle East, Australia) representing 5 of the recently described 7 BLV envelope-based genotypes. The BLV pol realtime PCR proved to be highly specific and sensitive with the detection of up to 1 copy of an internal control plasmid. The 95% confidence intervals for assay sensitivity and specificity were ≥98.27% and ≥98.33%, respectively. Restriction fragment length polymorphism and phylogenetic BLV pol-based sequence analysis of the investigated samples were performed and compared with the previous described BLV env-based genotypes. Grouping of the sequences based on the pol gene yielded similar results as the env gene-based assay.
Der Progress Test Tiermedizin (PTT) ist ein interdisziplinärer Fachwissenstest, der jährlich über... more Der Progress Test Tiermedizin (PTT) ist ein interdisziplinärer Fachwissenstest, der jährlich über alle Fachsemester der teilnehmenden Hochschulen durchgeführt werden soll, um den Stand und den Zuwachs an Fachwissen während des Studiums der Tiermedizin objektiv zu erfassen und zu messen. Dieser wird nicht benotet, sondern dient als Feedback-Instrument zur Unterstützung der Autonomie und Selbststeuerung des studentischen Lernprozesses (aktives Lernen) und zur Verbesserung der Ausbildungsqualität (Relevanz für den Beruf).
Genome announcements, 2015
A novel polyomavirus was identified in a fatally diseased Gouldian finch (Erythrura gouldiae). Th... more A novel polyomavirus was identified in a fatally diseased Gouldian finch (Erythrura gouldiae). The new polyomavirus, strain VL 1209, was detected using a broad-spectrum nested PCR.
Influenza A virus infections in marine mammals and terrestrial carnivores
Berliner und Münchener tierärztliche Wochenschrift
Influenza A viruses (IAV), members of the Orthomyxoviridae, cover a wide host spectrum comprising... more Influenza A viruses (IAV), members of the Orthomyxoviridae, cover a wide host spectrum comprising a plethora of avian and, in comparison, a few mammalian species. The viral reservoir and gene pool are kept in metapopulations of aquatic wild birds. The mammalian-adapted IAVs originally arose by transspecies transmission from avian sources. In swine, horse and man, species-adapted IAV lineages circulate independently of the avian reservoir and cause predominantly respiratory disease of highly variable severity. Sporadic outbreaks of IAV infections associated with pneumonic clinical signs have repeatedly occurred in marine mammals (harbour seals [Phoca vitulina]) off the New England coast of the U.S.A. due to episodic transmission of avian IAV. However, no indigenous marine mammal IAV lineages are described. In contrast to marine mammals, avian- and equine-derived IAVs have formed stable circulating lineages in terrestrial carnivores: IAVs of subtype H3N2 and H3N8 are found in canine p...
Serological detection systems for identification of cows shedding bovine foamy virus via milk
The biology of foamy viruses, their mode of transmission and disease potential in their natural h... more The biology of foamy viruses, their mode of transmission and disease potential in their natural host and after interspecies transmission are largely unknown. To gain insights into the prevalence of bovine foamy virus (BFV) and its zoonotic potential, enzyme-linked immunosorbent assays (ELISAs) were established to determine antibody responses against Gag, Env, and the non-structural protein Bet in bovine serum and milk. In Polish cattle, strong Gag reactivity was most frequent (41.5%) and strongly associated with Bet antibodies, Env antibodies were less frequent. German cattle showed a low overall BFV antibody prevalence of 6.8%. Besides clearly BFV-positive animals, a substantial number of weakly reacting cattle were identified. BFV-specific antibodies were also detectable in milk. BFV was isolated from PBLs and milk cells of BFV-positive cattle but not from antibody-negative or weakly reacting animals. The implications of these findings for the potential interspecies transmission of BFV to humans will be discussed.
Liver Pathology Associated with Increased Mortality in Turkey Breeder and Meat Turkey Flocks
Avian Diseases, 2014
Between 2006 and 2011 a series of disease conditions characterized by raised mortality and liver ... more Between 2006 and 2011 a series of disease conditions characterized by raised mortality and liver disorders occurred in turkey breeder flocks and in meat turkey flocks in Germany. The flocks were between 12 and 23 wk of age, and mostly hens were affected. Clinical signs were nonspecific and accompanied by mortality varying between 1% and 7%. Affected birds displayed swollen livers that were marbled with black and red spots and yellowish areas. The pericardium was filled with an amber fluid, and the coronary groove was extensively filled with fat. Spleens were swollen, and a serous fluid that seemed to leak from the liver was present in the body cavity. Histopathological findings in all but one case included fatty degeneration of hepatocytes with parenchymal collapse and associated hemorrhages. Some animals showed cholangitis and hepatitis with intranuclear inclusion bodies. In three cases with breeders, electron microscopy detected virus particles that were between 23 and 30 nm and similar to parvo- or picornavirus. In addition, picornavirus RNA was detected in the livers of one meat turkey flock. Investigations by PCR for circovirus, polyomavirus parvovirus, and aviadenovirus yielded negative results in all cases, but an aviadenovirus was isolated from livers twice and a reovirus from the intestines once. Supplementation with vitamin E and selenium seemed to improve the situation. The most likely diagnosis is lipidosis, a metabolic disorder with complex etiology, which has rarely been described in turkeys.
Distribution of lesions and antigen of highly pathogenic avian influenza virus A/Swan/Germany/R65/06 (H5N1) in domestic cats after presumptive infection by wild birds
In early 2006, the highly pathogenic avian influenza virus (HPAIV) H5N1 of the Asian lineage caus... more In early 2006, the highly pathogenic avian influenza virus (HPAIV) H5N1 of the Asian lineage caused the death of wild aquatic birds in Northern Germany. In the mainly affected areas, a trans-species transmission of HPAIV H5N1 to mammals occurred between birds and domestic cats and 1 Stone Marten (Martes foina), respectively. Here, we report lesions and distribution of influenza virus antigen in 3 cats infected naturally with HPAIV H5N1 A/swan/Germany/R65/06. The hemagglutinin partial nucleotide sequences of the viruses were genetically closely related to a H5N1 HPAIV obtained from a dead Whooper Swan (Cygnus cygnus) of the same area. At necropsy, within the patchy dark-red and consolidated lungs, there was granulomatous pneumonia caused by Aelurostrongylus sp. Histologically, the main findings associated with influenza in all cats were bronchointerstitial pneumonia and marked random hepatic necrosis. In addition, all animals displayed lymphoid necrosis in the spleen and Peyer's patches and necrosis of the adrenal cortex. Immunohistochemically, nucleoprotein of HPAIV was present intralesionally in the lungs, liver, adrenal glands, and lymphoid tissues. Oropharyngeal swabs were shown to be suited to detect HPAIV by quantitative real-time polymerase chain reaction (RT-PCR) in these cats, despite the paucity of influenza virus antigen in the upper respiratory tract by means of immunohistochemistry. The results show that outdoor cats in areas affected by HPAIV in wild birds are at risk for lethal infection. In conclusion, hepatic necrosis was, besides bronchointerstitial pneumonia, the primary lesion, suggesting that in naturally infected cats, damage to the liver plays an important role in the pathogenesis of H5N1 influenza.
Serological detection systems for identification of cows shedding bovine foamy virus via milk
Virology, 2007
The biology of foamy viruses, their mode of transmission and disease potential in their natural h... more The biology of foamy viruses, their mode of transmission and disease potential in their natural host and after interspecies transmission are largely unknown. To gain insights into the prevalence of bovine foamy virus (BFV) and its zoonotic potential, enzyme-linked immunosorbent assays (ELISAs) were established to determine antibody responses against Gag, Env, and the non-structural protein Bet in bovine serum and milk. In Polish cattle, strong Gag reactivity was most frequent (41.5%) and strongly associated with Bet antibodies, Env antibodies were less frequent. German cattle showed a low overall BFV antibody prevalence of 6.8%. Besides clearly BFV-positive animals, a substantial number of weakly reacting cattle were identified. BFV-specific antibodies were also detectable in milk. BFV was isolated from PBLs and milk cells of BFV-positive cattle but not from antibody-negative or weakly reacting animals. The implications of these findings for the potential interspecies transmission of BFV to humans will be discussed.
Veterinary Microbiology, 1999
0378-1135/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 ... more 0378-1135/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 -1 1 3 5 ( 9 9 ) 0 0 0 9 8 -X
Immunogenetics, 1995
Interferon-y (IFN-y) has been extensively studied in the mouse system. Produced by activated T ce... more Interferon-y (IFN-y) has been extensively studied in the mouse system. Produced by activated T cells and natural killer (NK) cells, this lymphokine possesses antiviral activity and exerts pleiotropic immunomodulatory activities, including activation of macrophages and NK cells and enhancement of major histocompatibility complex class I and II expression (for a review see . It is a key regulatory molecule in the T-helper cell type-1 (Th-1)-driven immune responses that are necessary for the elimination of intracellular pathogens (Scott
Antimicrobial Agents and Chemotherapy, 1995
The antiviral efficacy of acyclic nucleoside phosphonates, including 9-(2-phosphonylmethoxyethyl)... more The antiviral efficacy of acyclic nucleoside phosphonates, including 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and (R)-9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine [(R)-PMPDAP] against feline immunodeficiency virus (FIV) infection was determined. (R)-PMPDAP showed the highest selectivity index (>2,000) in vitro. Treatment of experimentally FIV-infected asymptomatic cats with PMEA or (R)-PMPDAP had no effect on the CD 4 ؉ /CD 8 ؉ ratio. However, mean plasma viral RNA concentrations decreased significantly in the (R)-PMPDAP-treated cats. Our data show that, in comparison to PMEA, (R)-PMPDAP is a more potent and less toxic inhibitor of FIV replication both in vitro and in vivo.
Uploads
Papers by Thomas Vahlenkamp