Rickettsia-like Organisms Research Articles

Rickettsia-like organisms in ticks and antibodies to spotted fever-group rickettsiae in mammals from northern Mississippi.

Studies were conducted from April through August during 1974 and 1975 on 30 randomly selected trapping sites in Wall Doxey State Park, Holly Springs National Forest, and 1.6 km south of the park in Marshall County, Mississippi to provide information on the occurrence of ticks involved in the maintenance and transmission of spotted fever-group rickettsiae in nature. Of 365 animals (14 species) collected, 186 (51%) were parasitized by 4,169 ticks. Species of ticks collected included: Dermacentor variabilis; Amblyomma americanum; Rhipicephalus sanguineus; Haemaphysalis leporispalustris; and Ixodes texanus. Of 2,105 ticks examined, 116 (5.5%) were positive for rickettsia-like organisms.

A tick/rickettsia survey of dogs in three counties in Mississippi, USA.

From March through September 1978 and March through June 1979, a total of 4473 ticks were removed from 560 dogs in Hinds, Lafayette, and Oktibbeha counties, Mississippi, USA. Rickettsia-like organisms were detected in 17 Rhipicephalus sanguineus , 7 Dermacentor variabilis , and 7 Amblyomma americanum . Seventy-four percent of the hemolymph-test-positive (HTP) ticks were removed from penned hunting dogs; the black-and-tan hound was the predominant breed parasitized. Ninety-four percent of the HTP ticks came from Lafayette Co., and the remaining 6% from Hinds Co. No HTP ticks were collected from Oktibbeha Co.

A rickettsiales-like infection in the pacific razor clam, Siliqua patula

An intracellular procaryotic rickettsiales-like organism was discovered in the digestive absorptive epithelium of the Pacific razor clam, Siliqua patula, from the Pacific Coast of Washington State. Of 80 animals examined, 30% contained the organisms, and all positive animals were between 1.5 mm and 3.0 cm shell length. The organisms appeared as basophilic inclusions averaging 5.0 μm in diameter. Ultrastructurally, the inclusions were membrane-bound vacuoles containing procaryotic forms which averaged 0.8 μm by up to 1.8 μm in length. These organisms had a double layer of trilaminar membrane which appeared to form blebs and outer membrane vesicles. The organisms were pleomorphic by both histological and electron microscopical examination. The host response to infection appeared to consist only of the rounding and detachment of the infected cells. Specific immunofluorescent tests for Rickettsia rickettsia, R. prowazekii, Coxiella burnetti, Chlamydia psittaci, and Legionella pneumophila were all negative when tested on impression smears of infected clam digestive gland.

Occurrence of rickettsia-like symbionts among species of the Aedes scutellaris group (Diptera:Culicidae).

Rickettsia-like organisms were seen by electron microscopy in the oocytes and nurse cells of Aedes hebrideus and A. scutellaris scutellaris and in the oocytes of A. pseudoscutellaris, a Samoan stock of A. polynesiensis and in three Fijian stocks of A. polynesiensis. None were found in the ovaries of A. alcasidi, A. s. katherinensis, A. cooki nor in a second stock of Samoan A. polynesiensis. It is suggested that the distribution of rickettsia-like symbionts among species of the A. scutellaris group conflicts in some cases with the hypothesis that these organisms are responsible for cytoplasmic incompatibility in the group.

Wissadula Proliferation in Jamaica II. Psyllid transmission and antibiotic therapy

AbstractField symptoms of Wissadula proliferation (WP) in Jamaica were reproduced on W. periplocifolia (L.) C. Presl. ex Thwaites test plants, using field‐collected or laboratory reared and infected Paracarsidara concolor Crawford. This psyllid naturally is associated with W. periplocifolia in the field. Diseased plants contained phloem‐restricted prokaryotes, most of which resembled the phloem‐restricted rickettsialike organisms (RLO) known to be associated with a small group of plant diseases. They were bound by a “cell wall” composed of a double unit membrane separated by an electron‐lucent layer. A small proportion of the prokaryotes, which were bound by only one recognizable unit membrane and were ill‐defined at the periphery, were difficult to distinguish from mycoplasmalike organisms (MLO). Penicillin, applied as a soil drench of 200—400 %mUg/ml caused remission of symptoms of the psyllid‐infected test plants 6—17 days after first effective application, with the concomitant disappearance of all of the structures in the resulting new growth. Since MLO are not known to be penicillin‐sensitive, it is proposed that the “MLO” were in fact, poorly preserved RLO and it is suggested that RLO may be the aetiological agent of WP. Achromycin also caused symptom remission in WP at a soil drench of 100—400 %mUg/ml, but was generally slightly slower‐acting than penicillin, eliciting a response in 12—23 days. Both antibiotics could produce lengthy remissions; neither seemed curative since two penicillin‐ and two achromycin‐treated plants redeveloped symptoms after cessation of treatment. WP was not transmitted by two cicadellids, Protalebra maculata Baker and Scaphytopius fuliginosus Osborn. P. concolor did not transmit disease to test plants of Abutilon hulseanum (Torr. & A. Gray) Torr, ex. Chapm. which was affected by a proliferation disease (Abutilon proliferation), symptomatologically similar to, and which occurred in the same locations, as WP. WP and AP thus may be aetiologically distinct. The putative RLO aetiology of WP provides evidence against Wissadula being an alternate host of the MLO‐associated coconut lethal yellowing (CLY) disease in Jamaica, a fact reinforced by negative psyllid transmission tests to CLY‐susceptible palms. The results for WP are discussed in relation to other diseases possibly caused by phloem‐restricted RLO.

Wissadula Proliferation in Jamaica

AbstractIn Jamaica, phloem‐restricted prokaryotes were found associated with a little leaf proliferation disease of Wissadula periplocifolia (L.) C. Presl. ex Thwaites. Electron microscopy of single ultrathin sections revealed circular, ovate and elongate profiles 120—500 nm in diameter/width and 125—4200 nm long. Most were bound by a double membrane and resembled the phloem‐restricted rickettsialike organisms associated with a small number of other plant diseases; others which were peripherally ill‐defined or without an obvious double membrane were indistinguishable from mycoplasmalike organisms. Further work is required to elucidate their taxonomic status and possible role in the aetiology of the disease. No potential aetiological agent was discovered for a symptomatologically similar disease of Abuliton hulseanum (Torr. & A. Gray) Torr. ex Chapm. which accurred intermixed with the Wissadula disease. The names Wissadula proliferation and Abutilon proliferation have been used to describe these newly recorded diseases.

Rickettsiae-infected ticks (acari: Ixodidae) and seropositive mammals at a focus for Rocky Mountain spotted fever in Connecticut, USA.

Ticks and wild mammals were collected in 1980 and 1981 from Newtown, Connecticut, USA, an area where 6 persons probably acquired Rocky Mountain spotted fever (RMSF) during 1978–1981. Dermacentor variabilis , the American dog tick, parasitized a variety of small and medium-sized mammals but was most prevalent on White-footed Mice and Raccoons. It was the only tick found infected with hemocyte-associated, rickettsia-like organisms; of the 347 adults removed from hosts during 1980–1981, 50 (14.4%) were positive by the hemolymph test. Direct immunofluorescence tests confirmed spotted-fever group (SFG) rickettsiae in 16 (4.6%) specimens. The following mammals contained antibodies to SFG rickettsiae: Eastern Chipmunks, Gray Squirrels, Meadow Voles, Virginia Opossums, Raccoons, a Short-tailed Shrew, Striped Skunks, White-footed Mice, Woodchucks, and Woodland Jumping Mice. Serologic results support clinical histories of human RMSF cases, and combined with tick-infectivity data suggest continued rickettsial activity in this ecosystem.

Occurrence of a Disease Caused by a Rickettsia-Like Organism in a Larval Population of the Cabbage Looper, Trichoplusia ni1 , in Southern California

A study of natural mortality in larvae of the cabbage looper, Trichoplusia ni (Hübner), feeding on experimental broccoli plantings in Riverside, Calif., revealed that ca. 10% of the larvae collected from July through October 1979 had a disease caused by a rickettsia-like organism. The disease occurred most commonly in 2nd- and 3rd- instars, where the rates of incidence were 12.8 and 15.2%, respectively. All larvae that developed patent infections died from the disease. The disease was most easily recognized in larvae which were reared individually in the laboratory on artificial diet. Disease signs included an opaque yellow-white discoloration on the body, incomplete shedding of the molted cuticle, reduced feeding activity, and a retarded growth rate with concomitantly increased larval longevity. At the histological level, the hemolymph of diseased larvae was milky white and contained numerous refractile vesicles that were diagnostic for the disease. Electron microscopy demonstrated slightly curved bacilliform particles, 160 by 420 nm, developing within these vesicles. Vesicles and particles also were found in the cytoplasm of epidermal, tracheal matrix, and fat body cells. The disease was transmitted to healthy T. ni larvae by injecting them with diluted hemolymph from diseased larvae. About 50% of the treated larvae developed typical signs of disease and subsequently died.

Insect Transmission of Plant Viruses and Mycoplasmalike and Rickettsialike Organisms

Insect Transmission of Plant Viruses and Mycoplasmalike and Rickettsialike Organisms

Association of a rickettsia-like organism with a disease of white clover

Association of a rickettsia-like organism with a disease of white clover

The rickettsia-like organisms TATLOCK (1943) and HEBA (1959): Bacteria phenotypically similar but genetically distinct from Legionella pneumophila and the WIGA bacterium : G. A. Hérbert, et al. 1980. Ann. Intern. Med. 92:45–52

The rickettsia-like organisms TATLOCK (1943) and HEBA (1959): Bacteria phenotypically similar but genetically distinct from Legionella pneumophila and the WIGA bacterium : G. A. Hérbert, et al. 1980. Ann. Intern. Med. 92:45–52

Endemicity of spotted fever group rickettsiae in Connecticut.

To compare rickettsial infectivity and seropositivity rates against spotted fever group (SFG) rickettsiae, ticks and wild mammals were collected from three areas where Rickettsia rickettsii was thought to be enzootic in Connecticut during 1978-1979, and from four additional sites (with no reported human cases) between 1976 and 1979. Of the 1,001 Dermacentor variabilis examined by the hemolymph test, 59 (5.9%) contained rickettsia-like organisms; direct immunofluorescence tests verified the presence of SFT rickettsiae in 14 specimens. Prevalence of rickettsiae-infected ticks at Newtown, an area where human cases of Rocky Mountain spotted fever probably originated, was 2.2%. Rates for six other areas ranged between 0 and 6.3%. Isolations included Rickettsia montana from four ticks collected at Branford and Woodbridge, and R. rickettsii (R-like strain) from the blood of an acutely ill person. Microagglutination (MA) tests indicated that 15 (14.9%) of 101 Peromyscus leucopus (white-footed mice) from Newtown had agglutinins in titers greater than or equal to 1:8 against R. rickettsii, whereas five of 92 white-footed mice (5.4%) from Brandord, West Hartford, Woodbridge, and Sharon were considered MA-positive. Indirect microimmunofluorescence tests of Procyon lotor (raccoon) sera revealed antibodies to R. rickettsii in 33 of 69 (47.8%) samples from Newtown and in two of 60 (3.3%) from Guilford. Additionally, 17 raccoons had sera specific to R. montana (n = 8) or to the 369-C rickettsia strain (n = 9). Since rickettsia-positive ticks are high-titered seropositive mammals occurred at widely separated sites in Connecticut there are probably several foci of SFG rickettsiae distributed throughout the D. variabilis range.

Serotypes of Tick-Borne Spotted Fever Group Rickettsiae from Western California

A rickettsial survey of ixodid ticks known to bite man was conducted in 1979 in four coastal counties of California to obtain isolates from tick species that might be involved in the transmission of spotted fever-like illnesses, and to examine serologic characteristics of the rickettsiae relative to defined members of the spotted fever group (SFG). One hundred and seventy (19.4%) of 877 ticks comprising three species were shown by hemolymph test to harbor rickettsia-like organisms. A total of 85 SFG rickettsia isolates was obtained by Vero-cell culture; 82 were from Dermacentor occidentalis, two were from D. variabilis, and one was from Ixodes pacificus. As determined by microimmunofluorescence, the isolates comprised four distinct serotypes. Two serotypes were obtained only from D. occidentalis, and one each only from D. variabilis and I. pacificus, respectively. Most D. occidentalis isolates possessed the serologic characteristics of Rickettsia rhipicephali, but there were similar to yet distinguishable from, R. rickettsii and are members of an unclassified serotype referred to as 364D. The two isolates from D. variabilis resembled the unclassified 369C serotype previously shown to be associated with this species and D. andersoni elsewhere in the United States. The I. pacificus isolate was similar to strains of the unclassified Tillamook serotype isolated from this tick in several localities in western Oregon. Representative strains of the four serotypes could also be distinguished on the basis of pathogenicity for Vero cells, chick embryos, guinea pigs, and/or meadow voles. The significance of these findings relative to occurrence of tick-associated illnesses in western California is briefly discussed.

Serotypes of spotted fever group rickettsiae isolated from Dermacentor andersoni (Stiles) ticks in western Montana.

Adult Dermacentor andersoni ticks were collected by flagging vegetation in 18 canyons bordering the Bitterroot Valley, Montana, an area where nearly 400 cases of Rocky Mountain spotted fever (RMSF) have occurred since 1900. Three hundred and nine (8.3%) of the 3,705 ticks collected contained hemocyte-associated rickettsia-like organisms of three morphologic types, coccobacillary, fine bacillary, and coarse bacillary (long forms). Only the coccobacillary and fine bacillary organisms stained with fluorescein-conjugated antibody specific for the spotted fever group. One hundred and six isolates of spotted fever-group rickettsiae obtained by inoculation of Vero cells with suspensions of hemolymph test-positive ticks were serologically typed by microimmunofluorescence. Four sharply distinct serotypes were obtained, including Rickettsia rickettsii (10 strains), R. montana (8 strains), R. rhipicephali (47 strains), and a hitherto undescribed serotype referred to as 369-C (41 strains). All but two isolates were obtained from west-side canyons where virtually all cases of RMSF had been acquired. The four serotypes were widely distributed on the west side as evidenced by their presence in 5-11 of the 13 collecting sites. Each serotype induced distinctive plaques and cytopathogenicity in Vero cell culture.

Protein synthesis in cell-free extracts of Coxiella burnetti.

Some aspects of protein biosynthesis were investigated in extracts of the obligate intracellular bacterium Coxiella burnetti. Sucrose gradient analysis revealed small quantities of 30S and 50S ribosomal subunits, few 70S ribosomes and no polysomes. Functional endogenous mRNA was not detected. In translation of exogenously added poly(U), extracts required Mg2+ (17 mM) and NH4+ (60 mM) for optimal polyphenylalanine synthesis; the optimum MG2+ requirement differed from that of Escherichia coli. The translation of coliphage Q beta RNA by C. burnetti extracts required Mg2+ (13 mM), NH4+ (60 mM) and an energy source for polypeptide synthesis, and was sensitive to chloramphenicol but not to cycloheximide. Under optimal conditions, the translation of Q beta RNA proceeded at a rate and to an extent equal to that obtained in a conventional E. coli system. Electrophoretic analysis of translation products made during incubation of C. burnetti extracts with polycistronic Q beta RNA revealed a major product with a molecular weight of about 14 000; this product co-electrophoresed with the coat protein extracted from Q beta phage propagated in E. coli. The results suggested that the extracellular form of the rickettsia-like organism, C. burnetti, possessed the full array of components necessary for the initiation, elongation and termination of polypeptides.

Mycoplasmas, Spiroplasmas, and Rickettsia-Like Organisms as Plant Pathogens

Mycoplasmas, spiroplasmas, and rickettsia-like organisms are considered to be the causal agents of yellows diseases, formally thought to be of viral origin. They belong to various groups of procaryotic microorganisms that are morphologically similar to or identical with members of the Mycoplas­ matales and Rickettsiales (6). Their similarity to these two orders has given rise to the terms mycoplasma-like organisms (MLO) and rickettsia-like organisms (RLO). The genus Spiroplasma has been placed in the order Mycoplasmatales. Mycoplasma-like organisms have been found in more than 200 plant species and in a large number of arthropods. Pathogenicity has not been proved in that Koch's postulates have not been fulfilled. The main reason for the failure to prove pathogenicity is that most attempts to isolate and cultivate these organisms have failed. Spiroplasmas occur as internal parasites in plants, leaiboppers, Drosoph­ ila, honey bees, and ticks. They have also been recently isolated from the surface of several flowers (25). Spiroplasmas have been cultivated on artifi­ cial media and their pathogenicity to plants has been demonstrated. Spiro­ plasma citri is the only recognized species in the family Spiroplasmataceae; all other spiroplasmas lack binomial names. Although many isolates are

Rocky mountain spotted fever in Connecticut: human cases, spotted-fever group rickettsiae in ticks, and antibodies in mammals.

Three parameters were used in 1976 and 1977 to assess the status of Rocky Mountain spotted fever (RMSF) in Connecticut--compilation and review of clinical data on suspected human cases for the 13-year period 1965--1977, examination of tick tissues for spotted fever-group rickettsiae by the hemolymph test and direct immunofluorescence, and analyses of mammalian sera for antibodies against Rickettsia rickettsii. There were six presumptive RMSF cases which probably originated in Connecticut. Four of these cases occurred in areas where the American dog tick, Dermacentor variabilis, abounds. A total of 2994 ticks were examined by the hemolymph test. Rickettsia-like organisms were observed in 67 (2.9%) of 2330 D. variabilis and two (0.6%) of 351 Ixodes sp. near scapularis. Fewer than one-half of these organisms stained positively with spotted fever-group conjugate. Microagglutination tests on 1093 mammalian sera indicated that eight (16%) of 49 raccoons, 14 (2.6%) of 549 white-tailed deer, eight (1.7%) of 470 white-footed mice, and one of two gray squirrels had agglutinins in titers greater than or equal to 1:8 against R. rickettsii. Spotted fever-group rickettsiae are present at low frequency in inland as well as coastal regions of Connecticut.

Rickettsia-like and mycoplasma-like organisms associated with two yellows-type diseases of strawberries in Queensland

Two yellows-type diseases occur in Queensland strawberries. Affected plants show purple or bronze pigmentation of older leaves, followed by the production of small chlorotic leaves. Flower production is inhibited, and some affected plants die. Thin-section electron microscopy showed that there were two diseases, one associated with rickettsia-like organisms (RLO) and the other with mycoplasma-like organisms (MLO), both of which were found only in sieve tubes. The MLO disease caused flower abortion but not green petals, and was not transmitted by Orosius argentatus (Evans), the tomato big bud vector. The RLO disease produced more bronze pigmentation and the young leaf chlorosis was interveinal rather than marginal. This organism was sensitive to penicillin, and soil drenches of 1 mg/ml every 5 days for 7 weeks caused complete remission of symptoms. No organisms were seen in thin sections of leaves after treatment. Although these RLO morphologically resembled those associated with rugose leaf curl (RLC) disease of legumes, experiments with the RLC vector Austroagallia torrida Evans indicated that they were probably distinct.

A light and electron microscope study of rickettsia-like organisms in the ovaries of mosquitoes of the Aedes scutellaris group.

The ovaries from some members of the Aedes scutellaris group were examined by light and electron microscopy to locate rickettsia-like organisms, and Culex pipiens fatigans was used as a control. It was found that light microscopy was unsatisfactory for this purpose since none of the available staining techniques demonstrates the organisms clearly and diagnostically. With the electron microscope it was shown that the organisms were by no means as common in the mosquitoes of the A. scutellaris group as in C.p. fatigans; they were quite frequently seen in A. polynesiensis, of sporadic occurrence in A. malayensis, rare in A. tabu and have not yet been identified with certainty in A. cooki.

761 PRIMARY HUMAN MONOCYTE CULTURE FOR DIAGNOSIS OF ROCKY MT. SPOTTED FEVER (RMSF)

Culture of human monocytes from patients was used to try to show intracellular Rickettsia sp. early in the course of clinical RMSF. Ten RMSF patients whose diagnosis was confirmed serologically & 9 non-RMSF patients were studied. Glass adherent mononuclear leukocytes were obtained after sedimentation of heparinized blood. Multiple coverslip cultures were established to allow sequential sampling. Five patients were studied prior to receipt of appropriate antibiotic therapy. Intracellular organisms morphologically characteristic of Rickettsia sp. visualized by Gimenez staining were seen in cultured monocytes from 3 of the 5 patients. Twenty-two separate cultures of monocytes from 10 RMSF patients who had received prior antibiotic therapy were negative for Rickettsia-like organisms. All 7 pre-therapy and 14 post-therapy cell cultures from non-RMSF patients were negative. The organisms seen were present in cells obtained on days 3,7, & 7 of clinical illness but could not be visualized until days 12 10, & 10 of in vitro observation. Thus 15-17 days from onset of clinical illness were required to see organisms. In contrast, serological conversion in 8 patients as measured by microimmunoflorescence & passive hemagglutination occurred 7-13 days after onset of illness. Monocyte cultures did not provide a more rapid diagnosis than serological conversion. Further refinement of this system may circumvent the hazard of culturing rickettsia from clinical materials in embryonated eggs or animals.