Anaplasma infection in free-ranging Iberian red deer in the region of Castilla-La Mancha, Spain

Organisms in the genus Anaplasma are obligate intracellular pathogens that multiply in both vertebrate and invertebrate hosts. The type species, Anaplasma marginale, causes bovine anaplasmosis and infects erythrocytes of the vertebrate host and undergoes a complex developmental cycle in ticks which serve as biological vectors. Infected cattle, wild ruminants and ticks can all serve as reservoirs of A. marginale. In this study, hunter killed Iberian red deer (Cervus elaphus hispanicus) from the region of Castilla-La Mancha in southwestern Spain were tested for Anaplasma infection. We found that 10% of the deer examined were seropositive for Anaplasma. Three A. marginale strains were subsequently obtained from salivary glands of Hyalomma marginatum that were removed from these deer, and the sequence of the major surface protein (msp)4 gene was determined for each strain and used for phylogenetic studies. Maximum parsimony analyses of msp4 sequences from H. marginatum ticks in comparison with New World cattle and bison isolates reported previously, suggested different origins for these Spanish A. marginale strains. The results of this study demonstrated that Iberian red deer are naturally infected with Anaplasma, and may therefore serve as a wildlife reservoir of the pathogen. Although the link between deer infection and the strains of A. marginale identified in ticks was not established, H. marginatum and Rhipicephalus bursa were identified as potential biological vectors for A. marginale in this region and may effect transmission of A. marginale between deer and cattle populations.     

Defining the immune response to Ehrlichia species using murine models

Pathogenic bacteria belonging to the family Anaplasmataceae include species of the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis, first known as the causative agent of human monocytic ehrlichiosis, also infects several vertebrate hosts including white-tailed deer, dogs, coyotes and goats. E. chaffeensis is transmitted from the bite of an infected hard tick, such as Amblyomma americanum. E. chaffeensis and other tick-transmitted pathogens have adapted to both the tick and vertebrate host cell environments. Although E. chaffeensis persists in both vertebrate and tick hosts for long periods of time, little is known about that process. Immunological studies will be valuable in assessing how the pathogen persists in nature in both vertebrate and invertebrate hosts. Understanding the host immune response to the pathogen originating from dual host backgrounds is also important to develop effective methods of diagnosis, control and treatment. In this paper, we provide our perspective of the current understanding of the immune response against E. chaffeensis in relation to other related Anaplasmataceae pathogens.     

Association of red‐mark syndrome with a Rickettsia‐like organism and its connection with strawberry disease in the USA

Red‐mark syndrome (RMS), a disease seen mostly in rainbow trout, Oncorhynchus mykiss, is of unknown aetiology. The research presented here indicates the presence of an intracellular bacterium in RMS‐affected fish. A positive reaction was observed using immunohistochemistry (IHC) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the United Kingdom using two different polyclonal antisera raised against Piscirickettsia salmonis. The same reaction was also seen with a number of different anti‐P. salmonis monoclonal antibodies (MAbs). A disease with similar clinical signs to RMS, referred to as strawberry disease (SD), has been reported in the USA. A Rickettsia‐like organism (RLO) has recently been associated with SD based on analysis of 16S rDNA sequences. Using the same panel of anti‐P. salmonis antibodies used to screen the RMS samples, similar staining was obtained in tissue of SD‐affected fish by IHC. A polymerase chain reaction (PCR) using RLO‐specific primers was also performed on RMS‐affected fish from the United Kingdom, and the samples were positive for the RLO 16S rRNA sequence. These findings suggest that the same aetiological agent may be responsible for RMS in the United Kingdom and SD in the USA.     

The presence of Rickettsia is associated with increased susceptibility of Bemisia tabaci (Homoptera: Aleyrodidae) to insecticides

BACKGROUND: The presence of certain symbiotic microorganisms may be associated with insecticide resistance in insects. The authors compared the susceptibility of two isofemale lines, Rickettsia-plus and Rickettsia-free, of the sweet potato whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) to major insecticides from different chemical groups, including imidacloprid, acetamiprid, thiamethoxam, pyriproxyfen, spiromesifen and diafenthiuron. RESULTS: While the Rickettsia-plus and Rickettsia-free lines showed no differences in their susceptibility to imidacloprid and diafenthiuron, higher susceptibility of the Rickettsia-plus line to acetamiprid, thiamethoxam, spiromesifen and especially pyriproxyfen was observed. LC(90) values indicated that the Rickettsia-free line was 15-fold more resistant to pyriproxyfen than the Rickettsia-plus line. CONCLUSION: Findings indicate that the infection status of B. tabaci populations by Rickettsia is an important consideration that should be taken into account when performing resistance monitoring studies, and may help in understanding the dynamics of B. tabaci resistance, symbiont-pest associations in agricultural systems and the biological impact of Rickettsia on whitefly biology.     

栉孔扇贝类立克次体自然感染调查及人工感染试验

从 1999年 10月至 2 0 0 1年 3月对导致栉孔扇贝 (Chlamysfarreri)大规模死亡的可疑病原进行了系统调查 ,在栉孔扇贝体内发现 1种细胞内寄生原核生物。根据该原核生物超微形态结构及所形成的包涵体形态特征及染色性质分析 ,初步确定为类立克次体 (Rickettsia likeorganisms ,RLO)。该RLO大小为 (3.6 2 3± 1.4 35 ) μm× (1.343± 0 .32 6 ) μm (n =4 5 ) ,主要寄生在栉孔扇贝的鳃、消化腺的上皮组织中。其感染率和感染强度与水温及栉孔扇贝死亡率呈负相关关系。人工感染试验证明 ,RLO可引起栉孔扇贝感染 ,但不形成大面积明显的组织病理变化。本研究表明 ,RLO对栉孔扇贝不具明显的致病性 ,不是导致栉孔扇贝大规模死亡的主要原因。     

Microbial pathogens in ticks, rodents and a shrew in northern Gyeonggi-do near the DMZ, Korea

A total of 1,618 ticks [420 individual (adults) and pooled (larvae and nymphs) samples], 369 rodents (Apodemus agrarius, Rattus norvegicus, Tscherskia triton, Mus musculus, and Myodes regulus), and 34 shrews (Crocidura lasiura) that were collected in northern Gyeonggi-do near the Demilitarized Zone (DMZ) of Korea during 2004-2005, were assayed by PCR for selected zoonotic pathogens. From a total of 420 individual and pooled tick DNA samples, Anaplasma (A.) phagocytophilum (16), A. platys (16), Ehrlichia (E.) chaffeensis (63), Borrelia burgdorferi (16), and Rickettsia spp. (198) were detected using species-specific PCR assays. Out of 403 spleens from rodents and shrews, A. phagocytophilum (20), A. platys (34), E. chaffeensis (127), and Bartonella spp. (24) were detected with species-specific PCR assays. These results suggest that fevers of unknown causes in humans and animals in Korea should be evaluated for infections by these vector-borne microbial pathogens.     

白蜡虫肠道微生物分析及立克次氏体分子检测

肠道微生物对于昆虫的生长和发育起着重要作用,不仅参与维生素合成、脂肪和碳水化合物的吸收与利用、孤雌生殖、信息素的合成,同时在抵御外来菌的侵入与定植以及在加强免疫系统的功能中也起着重要作用[1-2]。对于刺吸式昆虫来说,由于植物枝干韧皮部汁液营养组成不均衡,碳水化合物含量丰富而必需氨基酸组分欠缺或含量较低[3],这些昆虫体内的共生细菌能提供寄主昆虫所缺乏的必需氨     

Evaluation of conventional and real-time PCR assays for detection and differentiation of Spotted Fever Group Rickettsia in dog blood

Spotted Fever Group Rickettsia is important cause of emerging and re-emerging infectious disease in people and dogs. Importantly, dogs can serve as sentinels for disease in people. Sensitive and specific diagnostic tests that differentiate among species of infecting Rickettsia are needed. The objective of this study was to develop a sensitive and specific PCR that differentiates SFG Rickettsia infecting dog blood. Conventional and real-time PCR assays were developed using primers that targeted a small region of the ompA gene. Their sensitivity, determined by testing a cloned target sequence in the presence of host DNA, was 15–30 and 5 copies of DNA, respectively. Testing of Rickettsia cultures and analysis of Rickettsia gene sequences deposited in GenBank verified DNA could be amplified and used to differentiate species. DNA from the blood of infected dogs was also tested. Importantly, Rickettsia DNA was detected before seroconversion in some dogs. The species of infecting Rickettsia was also identified. We conclude these assays may assist in the timely diagnosis of infection with SFG Rickettsia. They may also facilitate the discovery of novel SFG Rickettsia infecting dogs, and in the investigation of dogs as sentinels for emerging rickettsioses.     

Rickettsia lusitaniae sp. nov. isolated from the soft tick Ornithodoros erraticus (Acarina: Argasidae)

In this study a novel Rickettsia from the spotted fever group, isolated from Ornithodoros erraticus soft ticks collected from pigpens in the south of Portugal, is described. After initial screening revealed Rickettsia-positive ticks, isolation attempts were then performed. Successful isolates were achieved by shell-vial technique using Vero E6 cells at 28 °C. Molecular characterization of the isolate was performed based on analysis of five rickettsial genes gltA, ompA, ompB, sca1 and htr with their subsequent concatenation along with other rickettsial species resulting in a clustering of the new isolate with Rickettsia felis and Rickettsia hoogstraalii. The degree of nucleotide sequence similarity with other rickettsiae fulfills the criteria for classification of our isolate as a novel species. The name Rickettsia lusitaniae sp. nov. (= CEVDI PoTiRo) is proposed for this new species found in O. erraticus.     

Rickettsial Infection in Animals,Humans and Ticks in Paulicéia,Brazil

A previous study in Paulicéia Municipality, south‐eastern Brazil, reported 9.7% of the Amblyomma triste ticks to be infected by Rickettsia parkeri, a bacterial pathogen that causes spotted fever in humans. These A. triste ticks were shown to be associated with marsh areas, where the marsh deer Blastocerus dichotomus is a primary host for this tick species. During 2008–2009, blood serum samples were collected from 140 horses, 41 dogs, 5 opossums (Didelphis albiventris) and 26 humans in farms from Pauliceia Municipality. Ticks were collected from these animals, from vegetation and from additional wildlife in these farms. Overall, 25% (35/140) of the horses, 7.3% (3/41) of the dogs, 3.8% (1/26) of the humans and 100% (5/5) of the opossums were seroreactive (titre ≥64) to spotted fever group (SFG) Rickettsia spp. Multivariate statistical analysis indicated that horses that were allowed to forage in the marsh were 4.8 times more likely to be seroreactive to spotted fever group (SFG) Rickettsia spp than horses that did not forage in the marsh. In addition, horses that had been living in the farm for more than 8.5 years were 2.8 times more likely to be seroreactive to SFG Rickettsia spp than horses that were living for ≤8.5 years. Ticks collected from domestic animals or from vegetation included Amblyomma cajennense, Amblyomma coelebs, Amblyomma dubitatum, Dermacentor nitens and Rhipicephalus microplus. By PCR analyses, only one pool of A. coelebs ticks from the vegetation was shown to be infected by rickettsiae, for which DNA sequencing revealed to be Rickettsia amblyommii. Ticks (not tested by PCR) collected from wildlife encompassed A. cajennense and Amblyomma rotundatum on lizards (Tupinambis sp), and A. cajennense and A. triste on the bird Laterallus viridis. Our results indicate that the marsh area of Paulicéia offers risks of infection by SFG rickettsiae.