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L A Magnarelli

Publications and source records attributed to L A Magnarelli.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cloning of the gene encoding the 44-kilodalton antigen of the agent of human granulocytic ehrlichiosis and characterization of the humoral response.

Antibodies in the sera of patients with human granulocytic ehrlichiosis (HGE) commonly recognize a 44-kDa antigen. We cloned the gene encoding the 44-kDa protein of the agent of HGE (aoHGE) by probing an aoHGE lambda ZAP II genomic DNA expression library with sera from aoHGE-infected mice. The gene, hge-44, is part of a multigene family, with sequence similarity to the Anaplasma marginale msp-2 genes. RNA-PCR studies confirmed that hge-44 is expressed by aoHGE cultured in HL-60 cells and by aoHGE during murine infection. Recombinant HGE-44, expressed and purified as a glutathione transferase fusion protein, was used as the substrate in immunoblots to help diagnose HGE. Antibodies in eight sera from eight patients with HGE and in two sera from two aoHGE-infected mice bound recombinant HGE-44. Antibodies in the sera of healthy individuals or patients with Ehrlichia chaffeensis or Borrelia burgdorferi infection did not recognize HGE-44. We conclude that hge-44 is a member of a multigene family and that hge-44 is expressed and elicits specific antibodies during infection.

Amino Acid Sequence↗
PubMed1998

Human exposure to a granulocytic Ehrlichia and other tick-borne agents in Connecticut.

Indirect fluorescent-antibody (IFA) staining methods with Ehrlichia equi (MRK or BDS strains) and Western blot analyses containing a human granulocytic ehrlichiosis (HGE) agent (NCH-1 strain) were used to confirm probable human cases of infection in Connecticut during 1995 and 1996. Also included were other tests for Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis (HME), Babesia microti, and Borrelia burgdorferi. Thirty-three (8.8%) of 375 patients who had fever accompanied by marked leukopenia or thrombocytopenia were serologically confirmed as having HGE. Western blot analyses of a subset of positive sera confirmed the results of the IFA staining methods for 15 (78.9%) of 19 seropositive specimens obtained from different persons. There was frequent detection of antibodies to a 44-kDa protein of the HGE agent. Serologic testing also revealed possible cases of Lyme borreliosis (n = 142), babesiosis (n = 41), and HME (n = 21). Forty-seven (26.1%) of 180 patients had antibodies to two or more tick-borne agents. Therefore, when one of these diseases is clinically suspected or diagnosed, clinicians should consider the possibility of other current or past tick-borne infections.

Animals↗
PubMed1998

Temporal correlations between tick abundance and prevalence of ticks infected with Borrelia burgdorferi and increasing incidence of Lyme disease.

The abundance of host-seeking Ixodes scapularis nymphs, the principal vector for the Lyme disease agent, Borrelia burgdorferi, in Old Lyme, Lyme, and East Haddam, Connecticut, was compared with the incidence of reported human Lyme disease in the 12-town area around the Connecticut River and the State of Connecticut for the period 1989 to 1996. Ticks were sampled from lawns and woodlands by dragging flannel over the vegetation and examined for the presence of B. burgdorferi by indirect fluorescent antibody staining. The infection rate of the nymphal ticks by B. burgdorferi during the 9-year period was 14.3% (of 3,866), ranging from 8.6% (1993) to 24.4% (1996). The incidence of Lyme disease was positively correlated with tick abundance in the 12 town area (r = 0.828) and the State of Connecticut (r = 0.741). An entomological risk index based upon the number of I. scapularis ticks infected by B. burgdorferi was highest in 1992, 1994, and 1996 and was highly correlated with the incidence of Lyme disease in Connecticut (r = 0.944). The number of Lyme disease cases has been influenced, in part, by annual changes in population densities of I. scapularis and, presumably, a corresponding change in the risk of contact with infected ticks. Based upon tick activity and spirochetal infection rates, epidemiologically based Lyme disease case reports on a regional scale appear to reflect real trends in disease.

Animals↗
PubMed1998

Serologic survey for antibodies to Borrelia burgdorferi in white-tailed deer in Ontario.

Serum samples collected from 623 white-tailed deer (Odocoileus virginianus) in southern Ontario (Canada) from 1985 to 1989 were tested for antibodies to Borrelia burgdorferi using an indirect fluorescent antibody (IFA) staining method. Samples from 150 of the deer were also tested using an enzyme-linked immunosorbent assay (ELISA). At IFA titers of 1:64 and 1:128 deer with antibodies to B. burgdorferi appeared to be widespread throughout southern Ontario, with an apparent prevalence ranging from 3 to 47%. At IFA titres > or = 1:256 and ELISA titres > or = 1:160 deer with antibodies to B. burgdorferi were only present on Long Point which is the only known endemic focus of Ixodes scapularis, the primary vector for B. burgdorferi, in southern Ontario. At these titres the apparent prevalence of antibodies to B. burgdorferi on Long Point was only 5 to 7%, even though the mean intensity of infestation of adult I. scapularis on deer was > 180, and 60% of the adult ticks are infected with B. burgdorferi. Based on these results, white-tailed deer do not appear to be a good sentinel species for the distribution of B. burgdorferi.

Animals↗
PubMed1997

Antibodies to Ehrlichia equi in dogs from the northeastern United States.

OBJECTIVE: To determine whether dogs living in tickinfested areas of the northeastern United States had been exposed to Ehrlichia equi, an etiologic agent of granulocytic ehrlichiosis. DESIGN: Analyses of dog sera. ANIMALS: 106 ill dogs and 12 clinically normal dogs. PROCEDURE: Antibodies to E equi were detected by indirect fluorescent antibody staining methods and western blot analyses. RESULTS: 10 of 106 (9.4%) sera tested from ill, privately owned dogs living in tick-infested areas of Connecticut and New York state had antibodies to E equi, a member of the E phagocytophila genogroup. Titration end points ranged from 1:80 to 1:1,280. Immunoblots revealed antibodies to proteins of E equi having molecular masses of predominantly 29, 40, 44, 105, 120, and 160 kd. There was good agreement between results of serologic testing methods, but use of the human isolate (NCH-1 strain) in western blot analyses detected 2 additional seropositive dogs found to be negative by indirect fluorescent antibody staining methods with the MRK strain. CLINICAL IMPLICATIONS: Dogs living in areas where ixodes scapularis is abundant may be exposed to multiple pathogens, such as E equi or Borrelia burgdorferi. Although mild or subclinical infections with E equi may develop, dogs with marked leukopenia, thrombocytopenia, or anemia should be viewed as possibly having ehrlichiosis. Laboratory diagnosis should include examinations for morulae in granulocytes or monocytes in addition to serologic analyses.

Animals↗
PubMed1997

The early humoral response in human granulocytic ehrlichiosis.

The early antibody response in patients with human granulocytic ehrlichiosis (HGE) and in mice infected with the HGE agent was characterized by using sera to probe lysates of HL-60 cells infected with HGE organisms. Sera were obtained from 18 patients with HGE, mostly within the first 6 weeks of clinical infection, and from mice infected with the HGE agent for up to 3 weeks. A 44-kDa antigen was reactive with IgG in all 18 patients, and IgG to 40-, 65-, and 80-kDa antigens was present in 6, 8, and 7 patients, respectively. In addition, IgM to 40-, 44-, 65-, and 80-kDa antigens was found in 9, 5, 4, and 4 subjects. Immunoglobulins to antigens ranging between 95 and 125 kDa were detected less frequently. HGE agent-infected C3H/HeJ mice had an antibody response similar to that in humans. Thus, the 40- and 44-kDa proteins of the HGE agent elicit early strong antibody responses during infection. Characterization of the antigens recognized by antibodies during HGE should aid in diagnosis and understanding of the disease.

Animals↗
PubMed1997

Serologic diagnosis of canine and equine borreliosis: use of recombinant antigens in enzyme-linked immunosorbent assays.

Serum samples from dogs and equids suspected of having canine or equine borreliosis, respectively, were analyzed in polyvalent enzyme-linked immunosorbent assays (ELISAs) with whole-cell or recombinant antigens of Borrelia burgdorferi sensu stricto. Purified preparations of recombinant antigens included outer surface protein A (OspA), OspB, OspC, OspE, OspF, and p41-G (a fragment of flagellin). Of the 36 dog sera that reacted positively to whole-cell antigen, 32 (88.9%) contained antibodies to one or more recombinant antigens. Reactivities to OspF (88.9% positive) and p41-G (75% positive) were most prevalent. In analyses of 30 equid sera positive in an ELISA with whole cells, 24 (80%) contained antibodies to one or more recombinant antigens. Seropositivities in ELISAs with p41-G (50% positive) and OspF (46.7% positive) were more than twofold greater than in ELISAs with OspA, OspB, or OspC (10 to 20% positive). In parallel tests of eight canine and three equine sera, there was good agreement in results of Western blot (immunoblot) analyses and ELISAs. Although dog and equid sera with antibodies to whole-cell B. burgdorferi frequently reacted positively to one or more recombinant antigens, the inclusion of OspF and p41-G antigens in ELISAs was most useful in the serologic diagnosis of canine and equine borreliosis.

Animals↗
PubMed1997

An indirect immunofluorescence assay using a cell culture-derived antigen for detection of antibodies to the agent of human granulocytic ehrlichiosis.

An indirect immunofluorescence assay for the detection of human antibodies to the agent of human granulocytic ehrlichiosis (HGE) was developed and standardized. Antigen was prepared from a human promyelocytic leukemia cell line (HL-60) infected with a tick-derived isolate of the HGE agent (USG3). Suitable antigen presentation and preservation of cellular morphology were obtained when infected cells were applied and cultured on the slide, excess medium was removed, and cells were fixed with acetone. Use of a buffer containing bovine serum albumin and goat serum reduced background fluorescence, and use of an immunoglobulin G (gamma-specific) conjugate reduced nonspecific binding. The assay readily detected specific antibody from HGE patients and did not detect antibody from healthy individuals. No significant reactivity was noted in sera from patients with high titers of antibodies to other rickettsial species. We were able to identify antibodies reactive to USG3 antigen in samples from areas where HGE is endemic that had tested negative to other rickettsial agents. Animal sera reactive against Ehrlichia equi or Ehrlichia phagocytophila bound to the HGE antigen, indicating that the assay may be useful for veterinary use. Comparability between two different laboratories was assessed by using coded human sera exchanged between laboratories. Results from the two laboratories were similar, indicating that the assay can be easily integrated into use for routine testing for HGE. The assay was then compared to an assay using horse neutrophils infected with ehrlichiae. The two assays gave comparable results, indicating that the cell culture-derived antigen can be used for testing samples that have been previously tested with E. equi as an antigen. The new assay offers several advantages over other immunofluorescence methods that use animal-derived antigen and is suitable for use in testing for human antibodies to the HGE agent.

Animals↗
PubMed1997

Antibodies to multiple tick-borne pathogens of babesiosis, ehrlichiosis, and Lyme borreliosis in white-footed mice.

Serum samples from Peromyscus leucopus (white-footed mouse), collected in Connecticut (USA) in 1983, 1985, and during 1990 to 1993, were analyzed by an enzyme-linked immunosorbent assay (ELISA) or indirect fluorescent antibody (IFA) staining methods for antibodies to Borrelia burgdorferi (strain 2591), Babesia microti, Ehrlichia chaffeensis (Arkansas strain), and Ehrlichia equi (MRK strain). Of the 294 serum samples tested, 160 (54%) contained immunoglobulins to one or more of these pathogens. There were antibodies to two or more etiologic agents in 77 (48%) of the seropositive mice. Although it was uncommon to detect coexisting antibodies to all four pathogens (n = 5 positive mice), E. chaffeensis-reactive antibodies or immunoglobulins to E. equi were present along with those produced to B. burgdorferi and B. microti in 24 other mice. These rodents carry antibodies to several tick-borne pathogens at numerous sites in Connecticut and may play a role in the epizootiology of ehrlichiosis as well as babesiosis and Lyme borreliosis.

Animals↗
PubMed1996

Presence of Ixodiphagus hookeri (Hymenoptera: Encyrtidae) in two Connecticut populations of Ixodes scapularis (Acari: Ixodidae).

Two Connecticut populations of the black-legged tick, Ixodes scapularis (Say), the vector of Lyme disease spirochetes, Borrelia bugrdorferi sensu stricto Johnson, Schmid, Hyde, Steigerwalt & Brenner, in the northeastern United States, are parasitized by the encyrtid wasp Ixodiphagus hookeri (Howard), formerly Hunterellus hookeri. The wasp was first detected in ticks from a forested site in Bridgeport in 1992. I. hookeri was reared from 18.6% of 148 host-seeking I. scapularis nymphs. In 1993 and 1994, this wasp was found to parasitize 26.0% of 192 engorged nymphs from Bridgeport and 21.8% of 101 nymphs from the Bluff Point Coastal Preserve in Groton. Each parasitized nymph produced an average of 6-8 wasps (range, 3-16) with a female to male sex ratio of 1.9-1. Both study sites are wooded, geographically isolated tracts (Bridgeport, 176 ha and Bluff Point, 326 ha) with high densities (51-72/km2) of white-tailed deer, Odocoileus virginianus (Zimmerman), and superabundant tick populations similar to that of Prudence Island, RI, where I. hookeri also has been reported. We found that I. hookeri emerged from 16.3% of 399 engorged nymphs and 13.7% of 1,081 engorged nymphs collected as unfed ticks from Prudence Island in 1990 and 1991, respectively. No wasps were obtained from nymphs collected in Stamford (n = 38) or Old Lyme, CT (n = 241). A high proportion (23.1% of 39) of engorged nymphs obtained from Bridgeport deer produced I. hookeri. However, only 2 nymphs (6.7%) recovered from white-footed mice, Peromyscus leucopus (Rafinesque), at Bridgeport were parasitized by the wasp. None of the engorged larvae recovered from deer or mice and fed as nymphs in the laboratory produced I. hookeri (n = 26 from deer and n = 384 from mice). The presence of this wasp in I. scapularis at these 2 insular-like sites on the Connecticut mainland supports the observation that high tick densities are required for the establishment and maintenance of I. hookeri and that the potential role of this wasp in the biological control of I. scapularis is limited.

Animals↗
PubMed1996

Use of recombinant antigens of Borrelia burgdorferi in serologic tests for diagnosis of lyme borreliosis.

Recombinant antigens of outer surface proteins (Osps) OspA, OspB, OspC, OspE, and OspF of Borrelia burgdorferi sensu stricto and of p41-G, an antigenic region of flagellin of this spirochete, were tested with human sera in class-specific and polyvalent enzyme-linked immunosorbent assays (ELISAs). In analyses for immunoglobulin M (IgM) antibodies, 18 (85.7%) of 21 serum samples from persons who had been diagnosed as having Lyme borreliosis on the basis of the presence of erythema migrans reacted positively in ELISAs with one or more Osp antigens or the p41-G antigen. Eleven serum samples contained antibodies to OspC antigen, and of these, six also reacted to the p41-G antigen and to one or more of the other recombinant antigens. The remaining five serum samples reacted solely to OspC (n = 4) or to OspC plus OspA and OspE without reactivity to p41-G (n = 1). In analyses for IgG antibodies, seropositivity was comparable to that of IgM analyses and was marked by predominant reactivity to p41-G, OspC, and OspF. Similarly, all 21 serum samples were positive in polyvalent and class-specific ELISAs with whole-cell B. burgdorferi. Minor cross-reactivity was noted when sera from persons who had syphilis, periodontitis or other oral infections, or rheumatoid arthritis were tested with OspC, OspE, OspF, and p41-G. With relatively high degrees of specificity, ELISAs with recombinant antigens, particularly OspC and p41-G, can help to confirm B. burgdorferi infections.

Antibodies, Bacterial↗
PubMed1996

Novel Borrelia burgdorferi isolates from Ixodes scapularis and Ixodes dentatus ticks feeding on humans.

Seven cultures of Borrelia burgdorferi differing from strains B31 and ZS7 were identified from among 99 isolates from Ixodes scapularis ticks and from white-footed mice (Peromyscus leucopus) and 1 isolate from an Ixodes dentatus tick. Five of the six novel isolates from I. scapularis and the isolate from I. dentatus were from ticks feeding on humans. The six isolates from I. scapularis lacked OspA and OspB, four possessed an OspD band, and two reacted with an anti-OspC monoclonal antibody. Restriction fragment length polymorphisms of HindIII-digested DNAs from six OspA-negative isolates did not hybridize with radiolabeled ospA or LA88 DNA, and only isolate 46047 hybridized with the pG gene. Fragments similar to those recorded for the standard B. burgdorferi sensu stricto strains B31 and ZS7 were obtained with the fla and the HSP70 genes. Pulsed-field gel electrophoresis patterns of DNA digested with MluI included the specific B. burgdorferi sensu stricto band at 135 kbp for the five OspA-negative isolates from I. scapularis ticks. The six novel isolates apparently lack the 55-kbp plasmid encoding OspA. The pG-containing plasmid may be missing from all but isolate 46047. The isolate from the I. dentatus tick was similar to previous isolates from I. dentatus ticks feeding on rabbits. None of the isolates could be recovered from inoculated C3H/HeNCrlBR or white-footed mice. All isolates reacted with sera from humans with early or late Lyme disease. Our studies demonstrate that these borreliae occur in ticks feeding on humans, and therefore, at least some humans in the northeastern United States are likely being exposed to borreliae other than the classic B31-type strains that have thus far been isolated from humans.

Animals↗
PubMed1995

Current status of laboratory diagnosis for Lyme disease.

Laboratory tests have been used extensively to help diagnose Borrelia burgdorferi infections. In many cases, results of indirect fluorescent antibody (IFA) staining methods or an enzyme-linked immunosorbent assay (ELISA), combined or separate from findings of Western blot analyses, have confirmed clinical diagnoses of Lyme disease. Alternative assays, such as culturing or DNA detection by polymerase chain reaction (PCR) methods, can provide more definitive evidence of B. burgdorferi infection than can antibody assays. However, aside from being more expensive, culturing B. burgdorferi from human tissues and fluids gives us a low yield, while results of PCR analyses can be as misleading as those obtained by performing IFA staining methods or an ELISA if there are false-negative or false-positive reactions. With increased knowledge of human immune responses to key proteins of B. burgdorferi, such as those with molecular masses of 21, 31, 34, 39, 41, and 93 kilodaltons, Western blot analyses are being used more frequently to confirm B. burgdorferi infections. These methods have been particularly helpful in identifying false-positive reactions in an ELISA. Until highly sensitive and specific assays have been adequately standardized, diagnosis of Lyme disease should be based primarily on clinical and epidemiologic evidence.

Antibodies, Bacterial↗
PubMed1995

Ticks (Acari: Ixodidae) infesting wild birds (Aves) and white-footed mice in Lyme, CT.

Birds were captured and recaptured (20.8% of 5,297) with Japanese mist nets, and white-footed mice, Peromyscus leucopus (Rafinesque), were caught and recaught (69.1% of 355) with Sherman box traps during the late spring, summer, and early fall from July 1989 through October 1991 to study tick-host relationships in Lyme, CT. Ixodes scapularis Say, a vector of Lyme disease spirochetes, Borrelia burgdorferi sensu stricto Johnson, Schmid, Hye, Steigerwalt & Brenner, infested 803 birds (15.2%) in 36 species and 148 (40.3%) of the mice. This tick dominated both birds (94.4% of 4,065 ticks) and mice (82.6% of 529 ticks). Other ticks that were recovered from birds were Haemaphysalis leporispaustris (Packard) (23 birds in seven species), I. dentatus Marx (34 birds in 14 species), and Dermacentor variabilis (Say) (two birds in two species). The latter was also collected from 12.7% of the 355 mice (n = 92 ticks). Infestations of I. scapularis were high for worm-eating warblers (30.6% of 111), ovenbirds (44.4% of 286), common yellowthroats (27.1% of 188), hooded warblers (35% of 80), Carolina wrens (50.9% of 110), house wrens (21.6% of 102), wood thrushes (23.0% of 867), veeries (32.5% of 246), and American robins (36.2% of 69). Coinfestation by larvae and nymphs of I. scapularis was significantly high for Carolina wrens (35.7% of 56 infested individuals), veeries (27.2% of 80), American robins (29.4% of 25), and common grackle (19.0% of 5), possibly enhancing transmission of B. burgdorferi. Mean crowding on larvae by nymphs, measured by Lloyd's index (1967), was highest for these four species (range 1.19-5.76). Seasonal patterns of infestation for each species of bird can account for much of the differences in degree of coinfestation. High infection rates by B. burgdorferi in larvae removed from some of these birds (14.9-20.0%) were found on those birds with both high numbers of larvae and nymphs. Spirochetemia in most avian hosts may be short and only certain species with concurrent infestations of nymphs and larvae may function effectively as reservoirs.

Animals↗
PubMed1995

Hemocytic rickettsia-like organisms in ticks: serologic reactivity with antisera to Ehrlichiae and detection of DNA of agent of human granulocytic ehrlichiosis by PCR.

Ixodid ticks were collected from Connecticut, Massachusetts, Missouri, Pennsylvania, Rhode Island, and British Columbia (Canada) during 1991 to 1994 to determine the prevalence of infection with hemocytic (blood cell), rickettsia-like organisms. Hemolymph obtained from these ticks was analyzed by direct and indirect fluorescent antibody (FA) staining methods with dog, horse, or human sera containing antibodies to Ehrlichia canis, Ehrlichia equi, or Rickettsia rickettsii. Of the 693 nymphal and adult Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, and Ixodes pacificus ticks tested with dog anti-E. canis antiserum, 209 (32.5%) contained hemocytic bacteria. The prevalence of infected ticks varied greatly with species and locale. In parallel tests of duplicate hemolymph preparations from adult I. scapularis ticks, the hemocytic organisms reacted positively with E. canis and/or E. equi antisera, including sera from persons who had granulocytic ehrlichiosis. In separate PCR analyses, DNA of the agent of human granulocytic ehrlichiosis was detected in 59 (50.0%) of 118 adult and in 1 of 2 nymphal I. scapularis ticks tested from Connecticut. There was no evidence of Ehrlichia chaffeensis DNA in these ticks. In indirect FA tests of hemolymph for spotted fever group rickettsiae, the overall prevalence of infection was less than 4%. Specificity tests of antigens and antisera used in these studies revealed no cross-reactivity between E. canis and E. equi or between any of the ehrlichial reagents and those of R. rickettsii. The geographic distribution of hemocytic microorganisms with shared antigens to Ehrlichia species or spotted fever group rickettsiae is widespread.

Anaplasmataceae↗
PubMed1995

Coexistence of antibodies to tick-borne pathogens of babesiosis, ehrlichiosis, and Lyme borreliosis in human sera.

Serum specimens from persons with or without Lyme borreliosis were analyzed by indirect fluorescent antibody staining methods for total immunoglobulins to Babesia microti, Ehrlichia chaffeensis (Arkansas strain), and Ehrlichia equi (MRK strain). There was serologic evidence of human exposure to multiple tick-borne agents in 15 (6.6%) of 227 serum samples obtained in Connecticut and Minnesota. Of these, 10 serum samples were from Connecticut patients who had erythema migrans and antibodies to Borrelia burgdorferi (range, 1:160 to 1:40, 960). A maximal antibody titer of 1:640 was noted for a B. microti infection, whereas titration end points of 1:640 and 1:1,280 were recorded for E. chaffeensis and E. equi seropositives, respectively. In specificity tests, there was no cross-reactivity among the antisera and antigens tested for the four tick-borne pathogens. On the basis of serologic testing, a small group of persons who had Lyme borreliosis had been exposed to one or more other tick-borne agents, but there was no clinical diagnosis of babesiosis or ehrlichiosis. Therefore, if the clinical picture is unclear or multiple tick-associated illnesses are suspected, more extensive laboratory testing is suggested.

Animals↗