RESUMO
BACKGROUND: Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA) in humans and tick-borne fever (TBF) in ruminants. The bacterium invades and replicates in phagocytes, especially in polymorphonuclear granulocytes. METHODS: In the present study, skin biopsies and ticks (Ixodes ricinus) were collected from tick feeding lesions on 38 grazing lambs between two and three weeks after access to pastures. The histopathological changes associated with tick bites and A. phagocytophilum infection, were described. In addition the skin biopsies were examined by immunohistochemistry. Furthermore, samples from blood, skin biopsies and ticks were examined by serology, PCR amplification of msp2 (p44), genotyping of rrs (16S rRNA) variants, and compared with the results obtained from histological and immunohistochemical investigations. RESULTS: Tick bites were associated with chronic and hyperplastic inflammatory skin lesions in this study. A. phagocytophilum present in skin lesions were mainly associated with neutrophils and macrophages. Bacteria were occasionally observed in the Tunica media and Tunica adventitia of small vessels, but were rarely found in association with endothelial cells. PCR and genotyping of organisms present in blood, ticks and skin biopsies suggested a haematogenous and a local spread of organisms at the tick attachment sites. CONCLUSIONS: The present study describes different aspects of A. phagocytophilum infection at the site of tick bite, and indicates that A. phagocytophilum rarely associates with endothelium during the early pathogenesis of infection.
Assuntos
Anaplasma phagocytophilum/isolamento & purificação , Anaplasmose/microbiologia , Mordeduras e Picadas/veterinária , Ixodes/microbiologia , Doenças dos Ovinos/microbiologia , Doenças dos Ovinos/parasitologia , Doenças Transmitidas por Carrapatos/veterinária , Anaplasma phagocytophilum/genética , Anaplasmose/sangue , Anaplasmose/transmissão , Animais , Anticorpos Antibacterianos/sangue , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Biópsia/veterinária , Contagem de Células Sanguíneas , DNA Bacteriano/química , DNA Bacteriano/genética , Imuno-Histoquímica/veterinária , Reação em Cadeia da Polimerase/veterinária , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética , Ovinos , Doenças dos Ovinos/transmissão , Doenças Transmitidas por Carrapatos/sangue , Doenças Transmitidas por Carrapatos/microbiologia , Doenças Transmitidas por Carrapatos/transmissãoRESUMO
BACKGROUND: Anaplasma phagocytophilum infection in domestic ruminants is widespread in the coastal areas of southern Norway. The bacteria may persist in mammalian hosts. Several genetic variants of A. phagocytophilum exist. In the present study, we investigate whether superinfection occurs in the acute and persistent phase of the infection. METHODS: Five-month-old lambs of the Norwegian Dala breed were experimentally infected with two 16S rRNA gene variants of A. phagocytophilum, i.e. A. phagocytophilum variant 1 (GenBank accession number M73220) and variant 2 (GenBank acc. no. AF336220). Eighteen lambs were used, two lambs in each group. Eight groups were experimentally inoculated with either variant 1 or 2 on day 0. Six of these groups were then challenged with the other variant on either days 7, 42 or 84, respectively. One group was left uninfected. The occurrence of A. phagocytophilum in blood samples was determined using semi-nested PCR analysis and gene sequencing. Specific antibodies were measured by an indirect immunofluorescence antibody assay (IFA). RESULTS: A. phagocytophilum variant 1 and 2 differed significantly with regards to clinical reaction and cross-immunity in infected lambs. Both variants were found in the blood after challenge. However, variant 1 was detected most frequently. CONCLUSION: The present experiment indicates that superinfection of different genotypes occurs during the acute as well as the persistent phase of an A. phagocytophilum infection, even in lambs protected against the challenged infection.
Assuntos
Anaplasma phagocytophilum/fisiologia , Ehrlichiose/veterinária , Doenças dos Ovinos/microbiologia , Anaplasma phagocytophilum/classificação , Anaplasma phagocytophilum/genética , Animais , Anticorpos Antibacterianos/sangue , Ehrlichiose/microbiologia , Interações Hospedeiro-Patógeno , RNA Ribossômico 16S/genética , Ovinos , Fatores de TempoRESUMO
A study was performed to evaluate blood from young lambs using the Technicon H*1 hematology analyzer, with emphasis on RBC parameters, comparison of tripotassium EDTA and heparin, and the effects of storage on heparinized blood. Blood samples from lambs 2 days to 18 weeks of age were analyzed within 6 hours, revealing a high precision, except for WBC counts in heparinized blood. The HCT values estimated by the H*1 correlated well (r(2)=.90) with those obtained by the microhemotocrit method. Mean hematologic values obtained for heparinized blood differed by up to 4% from values obtained from blood collected into EDTA. WBC counts decreased 8.5% in heparinized blood stored at 4 degrees C for 1 day, but differences observed in RBC counts were
