Immunization with adenoviral-vectored tick salivary gland proteins (SALPs) in a murine model of Lyme borreliosis

Prior exposure of vertebrate hosts to tick salivary proteins can induce specific immunity to tick infestation, as well as affording protection against tick-transmitted Borrelia burgdorferi infection in the mammalian host. Vaccination using an adenovirus expression system to deliver 4 tick salivary proteins (Ad-Salps) derived from Ixodes scapularis, Salp15, Salp25A, Salp25D, and Isac, was explored. Results indicate that vaccination with tick salivary proteins in an adenoviral vector can be used to modulate a Th1 response in the host and partially control spirochete load in immunized mice after infected tick challenge.

Bioprocess and bioreactor: next generation technology for production of potential plant-based antidiabetic and antioxidant molecules

Globally, diabetes and obesity are two of the most common metabolic diseases of the 21(st) century. Increasingly, not only adults but children and adolescents are being affected. New approaches are needed to prevent and treat these disorders and to reduce the impact of associated disease-related complications. Industrial-scale production using plant-root cultures can produce quantities and quality of inexpensive bioactive small molecules with nutraceutical and pharmaceutical properties. Using this approach, and targeting these diseases, a next generation approach to tackling this emerging global health crisis may be developed. Adventitious roots cultured in bioreactors under controlled and reproducible conditions have been shown effective for production of natural products. The liquid-phase airlift bioreactor in particular has been used successfully for culturing roots on an industrial-scale and thus may provide an economical production platform for expressing promising plant-based antidiabetic and antioxidant molecules. This review focuses on a next-generation, scalable, bioprocessing approach for adventitious and hairy root cultures that are a pesticide-free, seasonally-independent, plant-based source of three molecules that have shown promise for the therapeutic management of diabetes and obesity: corosolic acid, resveratrol and ginsenosides.

Kinetics of Borrelia burgdorferi infection in larvae of refractory and competent tick vectors

The acquisition of Borrelia burgdorferi by the larvae of competent and refractory ixodid ticks was assessed by quantitative polymerase chain reaction (PCR). Larvae were fed on infected mice, and the spirochete loads were determined during feeding and up to 93 d postfeeding. Amblyomma americanum (L.) was refractory to B. burgdorferi infection, with almost no detection of spirochete DNA during or postfeeding. In contrast, Ixodes scapularis Say supported high loads of spirochetes (10(3)-10(4) per larva). In Dermacentor variabilis (Say), B. burgdorferi uptake was reduced, with an average of 16 spirochetes per larvae acquired after 4 d of feeding, representing 1/195 of the counts in I. scapularis. However, during the first day postfeeding, the spirochete growth rate in D. variabilis reached 0.076 generations per hour, 7.7 times greater than the highest growth rate detected in I. scapularis. D. variabilis supported intense spirochete growth up to the fourth day postinfection, when the counts increased to an average of 282 spirochetes per larvae or 1/8.5 of the I. scapularis counts 4 d postfeeding. The kinetics of spirochete growth was unstable in D. variabilis compared with I. scapularis, and transmission of B. burgdorferi by D. variabilis could not be demonstrated. A cofeeding experiment indicated that I. scapularis feeding increased A. americanum spirochete uptake. These collective results indicate suboptimal conditions for B. burgdorferi uptake and colonization within A. americanum or the presence of anti-Borrelia factor(s) in this nonpermissive tick species.

Capillary feeding of specific dsRNA induces silencing of the isac gene in nymphal Ixodes scapularis ticks

Ixodes scapularis transmits several pathogens including Borrelia burgdorferi. Bioactive compounds in tick saliva support tick feeding and influence pathogen transmission to the mammalian host. These studies utilized oral delivery of dsRNA to silence an anticomplement gene (isac) in I. scapularis nymphs. Silencing of isac significantly reduced fed-tick weight compared to delivery of control lacZ dsRNA, and immunoblots specific for FlaB protein indicated a reduction in spirochete load in isac-silenced infected nymphs. SDS-PAGE demonstrated that isac gene silencing affected expression of a number of salivary and non-salivary gland proteins in ticks. Finally, multiple isac cDNA homologues were cloned, and these may represent a new gene family coexpressed during tick feeding. This work presents a novel oral delivery approach for specific gene silencing in I. scapularis nymphs and characterizes the effect of isac on blood-feeding in an attempt to block transmission of B. burgdorferi.

Differential infectivity of the Lyme disease spirochete Borrelia burgdorferi derived from Ixodes scapularis salivary glands and midgut

Blood fed nymphal Ixodes scapularis Say infected with Borrelia burgdorferi were dissected to obtain salivary gland and midgut extracts. Extracts were inoculated into C3H/HeJ mice, and ear, heart, and bladder were cultured to determine comparative infectivity. Aliquots of extracts were then analyzed by quantitative polymerase chain reaction to determine the number of spirochetes inoculated into mice. A comparative median infectious dose (ID50) was determined for both salivary gland and midgut extract inoculations. Our data demonstrated a statistically significant difference (P < 0.002) in the ID50 derived from salivary gland (average = 18) versus midgut (average = 251) extracts needed to infect susceptible mice. A rationale for the differential infectivity of salivary and midgut derived spirochetes is discussed.

Borreliacidal activity of saliva of the tick Amblyomma americanum

Amblyomma americanum (Linneaus) (Acari: Ixodidae), an important tick vector of human and animal disease, is not a competent vector of the bacterial agent of Lyme disease, Borrelia burgdorferi, although its range overlaps the geographical distribution of Lyme disease within the United States. A possible mechanism that could prevent acquisition of B. burgdorferi spirochetes from infected hosts is the toxic effect of A. americanum saliva on B. burgdorferi. The data presented here indicate that after 24 and 48 h of exposure to A. americanum saliva, significantly fewer B. burgdorferi were alive compared to treatment controls as assessed by spirochete motility under dark-field microscopy and resistance to the dead stain, propidium iodide. After 48 h, fewer than 13% of saliva-exposed B. burgdorferi were alive. In contrast, significantly more B. burgdorferi exposed to Ixodes scapularis (Acari: Ixodidae) saliva survived after 24 or 48 h compared to A. americanum saliva or treatment controls.

Sustained-release formulation of doxycycline hyclate for prophylaxis of tick bite infection in a murine model of Lyme borreliosis

The prophylactic potential of a single injection of sustained-release doxycycline hyclate (Atridox) was compared to that of a single oral dose of doxycycline hyclate in a murine model of Lyme borreliosis. Prophylaxis, as measured by the lack of cultivable spirochetes and demonstrable pathology, was noted for 43% of orally treated mice; in contrast, the sustained-release doxycycline hyclate completely protected mice from infection and resultant pathology.

How much pilocarpine contaminates pilocarpine-induced tick saliva?

Pilocarpine is often applied or injected into ticks to induce salivation, and the resulting saliva used to test for various pharmacological, biochemical and immunological activities. To measure the amount of pilocarpine in pilocarpine-induced tick saliva, an HPLC-MS/MS method, based on capillary strong cation exchange chromatography online with an ion trap mass spectrometer, was used to measure pilocarpine in the pg to ng range. Results indicate large concentrations of pilocarpine in Ixodes scapularis Say and Amblyomma americanum (Linnaeus) (Acari: Ixodidae) saliva, ranging from 3 to 50 mm. Due to the known effects of pilocarpine on smooth muscle and immune cells, appropriate controls are proposed and discussed for proper interpretation of results using this saliva preparation.

An analysis of spirochete load, strain, and pathology in a model of tick-transmitted Lyme borreliosis

Four laboratory-grown, low-passage isolates of Borrelia burgdorferi sensu stricto, B31, JD-1, 910255, and N40, were incorporated into Ixodes scapularis ticks to examine the pathogenesis of these isolates in mice after tick transmission. All isolates induced multifocal, lymphoid nodular cystitis, subacute, multifocal, necrotizing myocarditis, and a localized periostitis and arthritis of the femorotibial joint 6-18 weeks after tick infestation. In terms of the number of mice that demonstrated pathology in bladder, heart, and joint, the highest incidence of lesions occurred 12 weeks after tick bite. Utilizing the Taqman quantitative polymerase chain reaction (q-PCR) fluorogenic detection technology to amplify a conserved region of the flagellin gene, a trend was demonstrated between the number of spirochetes in tissue with duration of pathology. The q-PCR assay developed for this study was sensitive and could reliably measure as few as 1 to 10 spirochetes in the target tissues tested. A higher percentage of B31- and N40-infected mice (92 and 100%, respectively) developed myocarditis than JD-1- or 910255-infected mice (67 and 46%, respectively) 12 weeks after tick bite. The amount of spirochetal DNA that could be amplified for heart at this time point was not statistically different between isolates, indicating a difference in virulence between B31 and N40 relative to JD-1 and 910225. N40-infected mice demonstrated a significantly higher spirochete load (an average of 1.23 spirochetes/mg of tissue, p = 0.045) in femorotibial joints 18 weeks after infection, with 60% of these mice maintaining lesions compared with those infected with B31 (13%), JD-1 (25%), or 910255 (50%), which averaged <0.5 spirochetes/mg of tissue. This mouse model of Lyme borreliosis, including the ability to monitor lesion development and spirochete load, can facilitate the testing of therapeutic regimens for the later stages of tick-transmitted Lyme disease and help investigate aspects of the immunopathogenesis of lesion development.

A preliminary linkage map of the hard tick, Ixodes scapularis

A linkage map of the Ixodes scapularis genome was constructed, based upon segregation amongst 127 loci. These included 84 random amplified polymorphic DNA (RAPD) markers, 32 Sequence-Tagged RAPD (STAR) markers, 5 cDNAs, and 5 microsatellites in 232 F1 intercross progeny from a single, field-collected P1 female. A preliminary linkage map of 616 cM was generated across 14 linkage groups with one marker every 10.8 cM. Assuming a genome size of approximately 109 bp, the relationship of physical to genetic distance was found to be approximately 300 kb/cM in the I. scapularis genome.

A preliminary linkage map of the tick, Ixodes scapularis

A linkage map of the Ixodes scapularis genome was constructed based upon segregation amongst 127 loci. These included 84 random amplified polymorphic DNA (RAPD) markers, 32 Sequence-Tagged RAPD (STAR) markers, 5 cDNAs, and 5 microsatellites in 232 F1 intercross progeny from a single, field-collected P1 female. A preliminary linkage map of 616 cM was generated across 14 linkage groups with one marker every 10.8 cM. Assuming a genome size of approximately 10(9) bp, the relationship of physical to genetic distance is approximately 300 kb/cM in the I. scapularis genome.

Isolation and characterization of Borrelia parkeri in Ornithodoros parkeri (Ixodida: Argasidae) collected in Colorado

This study describes the identification of Borrelia parkeri spirochetes in Colorado. Two isolates of B. parkeri (6230 and 6232) were recovered from Ornithodoros parkeri Cooley ticks collected at an inactive prairie dog town in Moffat County. Both isolates were partially characterized by sequencing and subsequent parsimony and neighbor-joining analyses of appropriate regions of the 16S ribosomal RNA, flagellin and P66 genes. Analyses of the 16S gene sequences from the Colorado isolates indicated that they were more closely related to B. parkeri and B. tucatae than to B. hermsii or the other species of Borrelia investigated in this study. Additional analyses of amino acid sequences for flagellin and P66, however, clearly demonstrated that isolates 6230 and 6232 were most closely related to B. parkeri. The possible significance of B. parkeri as an agent of human disease is discussed.

Identification of an IL-2 binding protein in the saliva of the Lyme disease vector tick, Ixodes scapularis

A potent inhibitor of mitogen-stimulated T cell proliferation exists in the saliva of several species of hard ticks, including the Lyme disease vector tick, Ixodes scapularis. Our characterization of this phenomenon has led to the identification of a possible mechanism for the T cell inhibitory activity of I. scapularis saliva. The T cell inhibitor can overcome stimulation of mouse spleen cells with anti-CD3 mAb; however, a direct and avid interaction with T cells does not appear to be necessary. Tick saliva inhibits a mouse IL-2 capture ELISA, suggesting that a soluble IL-2 binding factor is present in the saliva. This hypothesis was verified by using a direct binding assay in which plate-immobilized tick saliva was shown to bind both mouse and human IL-2. Elimination of the IL-2 binding capacity of saliva in the in vitro assays by trypsin digestion demonstrated that the IL-2 binding factor is a protein. These experiments comprise the first demonstration of the existence of such a secreted IL-2 binding protein from any parasite or pathogen. This arthropod salivary IL-2 binding capacity provides a simple mechanism for the suppression of T cell proliferation as well as for the activity of other immune effector cells that are responsive to IL-2 stimulation. Relevance of the tick T cell inhibitory activity to the human immune system is demonstrated by the ability of tick saliva to inhibit proliferation of human T cells and CTLL-2 cells grown in the presence of human IL-2.

Resistance to Lyme disease in decorin-deficient mice

Microbial adhesion to the host tissue represents an early, critical step in the pathogenesis of most infectious diseases. BORRELIA: burgdorferi, the causative agent of Lyme disease (LD), expresses two surface-exposed decorin-binding adhesins, DbpA and DbpB. A decorin-deficient (Dcn(-/-)) mouse was recently developed and found to have a relatively mild phenotype. We have now examined the process of experimental LD in Dcn(-/-) mice using both needle inoculation and tick transmission of spirochetes. When exposed to low doses of the infective agent, Dcn(-/-) mice had fewer Borrelia-positive cultures from most tissues analyzed than did Dcn(+/+) or Dcn(+/-) mice. When the infection dose was increased, similar differences were not observed in most tissues but were seen in bacterial colonization of joints and the extent of Borreila-induced arthritis. Quantitative PCR demonstrated that joints harvested from Dcn(-/-) mice had diminished Borrelia numbers compared with issues harvested from Dcn(+/+) controls. Histological examination also revealed a low incidence and severity of arthritis in Dcn(-/-) mice. Conversely, no differences in the numbers of Borreila-positive skin cultures were observed among the different genotypes regardless of the infection dose. These differences, which were observed regardless of genetic background of the mice (BALB/c or C3H/HeN) or method of infection, demonstrate the importance of decorin in the pathogenesis of LD.

Infection of Ixodes scapularis (Acari: Ixodidae) with Borrelia burgdorferi using a new artificial feeding technique

To study interactions between Ixodes scapularis (Say) and Borrelia burgdorferi, an artificial feeding system was refined to allow controlled manipulation of single variables. The feeding system uses a mouse skin mounted on a water-jacketed glass membrane feeder. I. scapularis were infected using either BSK-H-cultured B. burgdorferi spirochetes or a B. burgdorferi-infected mouse skin as the source of spirochetes. Sixty-six percent of nymphs successfully fed to repletion using the artificial feeding systems with at least 75% of nymphs becoming infected with B. burgdorferi. Strain B31 B. burgdorferi spirochetes from passages 2-17 were equally infectious to nymphal ticks. At concentrations of one spirochete per microliter, 12% of nymphs acquired infection and 14 and 100 spirochetes per microliter resulted in 50 and 100% infection rates, respectively. Eighty-nine percent of nymphs fed by artificial feeding molted to the adult stage. When subsequently fed as adults, these I. scapularis successfully transmitted infectious B. burgdorferi spirochetes to mice.

Coinfection with Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis suppresses IL-2 and IFN gamma production and promotes an IL-4 response in C3H/HeJ mice

Previously we demonstrated that Borrelia burgdorferi transmission by Ixodes scapularis suppressed IL-2 and IFN gamma production and promoted IL-4 production in mice. The present studies were conducted to determine whether coinfection with the human granulocytic ehrlichiosis (HE) agent would promote a Th2 cytokine response in mice. Transmission to the spleen of the agent of human granulocytic ehrlichiosis (aoHGE) and B. burgdorferi occurred 4 and 7 days, respectively, after tick infestation. Coinfection synergized to suppress splenic IL-2 production 7-14 days after tick infestion. Transmission of B. burgdorferi or aoHGE alone significantly decreased splenic IFN gamma 4-7 days after tick infestation, while coinfection suppressed IFN gamma production 7-14 days after tick infestation. Splenic IL-4 production was significantly increased 4 days after coinfection, and by day 10, aoHGE plus B. burgdorferi induced greater splenic IL-4 (57.2 pg/ml, 348% of control values) than either organism transmitted alone (aoHGE, 22.7 pg/ml, B. burgdorferi, 25.1 pg/ml). Coinfection enhanced expansion of splenic T cells, CD4+ lymphocytes and B cells while decreasing CD8+ T cells. These data demonstrate that aoHGE and B. burgdorferi, when cotransmitted, suppress a systemic IL-2 and IFN gamma response, while strongly promoting systemic IL-4 production in the susceptible host. The antigen(s) responsible for this polarization are unknown and will be the subject of future studies.

Vector competence of Ixodes muris (Acari: Ixodidae) for Borrelia burgdorferi

The vector competence of Ixodes muris (Bishopp & Smith) was determined for Borrelia burgdorferi, the etiologic agent of Lyme disease. Larval I. muris were fed on ICR outbred mice infected with the B-31 laboratory strain of B. burgdorferi. Replete larvae, at 5 d after feeding, were assayed for infection by culture in Barbour-Stoner-Kelly (BSK-H) media. Infection frequency in I. muris replete larvae was 66%. Resultant nymphs were fed on naive ICR outbred mice to determine the ability of I. muris to transmit infection. Infection frequency in fed nymphs declined to 38% and only 1/5 mice was positive for B. burgdorferi on ear biopsy culture. We demonstrated that I. muris is capable of acquiring and transmitting B. burgdorferi but is a relatively poor vector compared with I. scapularis (Say).

Transmission of the agent of human granulocytic ehrlichiosis by Ixodes spinipalpis ticks: evidence of an enzootic cycle of dual infection with Borrelia burgdorferi in Northern Colorado

Previous work described an enzootic cycle of Borrelia burgdorferi sensu lato (hereafter referred to as B. burgdorferi) maintained by the rodent Neotoma mexicana and the tick Ixodes spinipalpis in northern Colorado. We investigated the incidence of coinfection among rodents with the agent of human granulocytic ehrlichiosis (aoHGE). aoHGE was detected in 23.5% of 119 rodent spleens examined. Biopsy results indicated that 78 (65.5%) of the 119 rodents were positive for B. burgdorferi, whereas 22 (78.5%) of the 28 animals that harbored aoHGE were also infected with B. burgdorferi. In 14 of 25 I. spinipalpis tick pools, aoHGE was detected by amplifying both the 16s rRNA and p44 gene of aoHGE. The ability of I. spinipalpis to transmit aoHGE was examined in C3H/HeJ mice. aoHGE was detected in their blood 5 days after I. spinipalpis infestation. This study confirms that both B. burgdorferi and aoHGE can be transmitted by I. spinipalpis ticks and that there is a high incidence of coinfection in rodents, predominantly Peromyscus maniculatus and N. mexicana, that inhabit the foothills of northern Colorado.

Geographic survey of vector ticks (Ixodes scapularis and Ixodes pacificus) for infection with the Lyme disease spirochete, Borrelia burgdorferi

Populations of adult Ixodes scapularis and Ixodes pacificus, the two principal vectors of Lyme disease spirochetes in the United States, were collected from 17 sites in 12 states. Female ticks were fed on experimental rabbits; ticks and rabbits were subsequently examined for infection with Borrelia burgdorferi. Fourteen rabbits were exposed to I. scapularis ticks from the northeastern states of Connecticut, New York, New Jersey, and Maryland; all 14 rabbits became infected with B. burgdorferi. A total of 165/226 (73%) of these northeastern ticks was infected. Similarly, ticks from the midwestern states of Michigan, Wisconsin, and Minnesota transmitted infection to all three exposed rabbits; 29/51 (57%) of these midwestern I. scapularis were infected. In marked contrast, none of the 12 rabbits exposed to I. scapularis ticks from the southeastern states of South Carolina, Georgia, Florida, and Mississippi acquired infection with B. burgdorferi, and 0/284 (0%) of these ticks contained spirochetes. Four rabbits were exposed to I. pacificus collected from one location in California; 2/4 of these rabbits acquired infection and 2/57 (4%) of the I. pacificus were infected with B. burgdorferi. The antigenic profiles of all 58 strains tested were consistent with an identity of B. burgdorferi sensu lato. The availability of a human Lyme disease vaccine adds urgency to our efforts to calculate the ecological transmission risk throughout the United States, as an aid to the judicious use of such a vaccine.

Influence of outer surface protein A antibody on Borrelia burgdorferi within feeding ticks

Borrelia burgdorferi, the spirochetal agent of Lyme disease, is transmitted by Ixodes ticks. When an infected nymphal tick feeds on a host, the bacteria increase in number within the tick, after which they invade the tick's salivary glands and infect the host. Antibodies directed against outer surface protein A (OspA) of B. burgdorferi kill spirochetes within feeding ticks and block transmission to the host. In the studies presented here, passive antibody transfer experiments were carried out to determine the OspA antibody titer required to block transmission to the rodent host. OspA antibody levels were determined by using a competitive enzyme-linked immunosorbent assay that measured antibody binding to a protective epitope defined by monoclonal antibody C3.78. The C3.78 OspA antibody titer (>213 microgram/ml) required to eradicate spirochetes from feeding ticks was considerably higher than the titer (>6 microgram/ml) required to block transmission to the host. Although spirochetes were not eradicated from ticks at lower antibody levels, the antibodies reduced the number of spirochetes within the feeding ticks and interfered with the ability of spirochetes to induce ospC and invade the salivary glands of the vector. OspA antibodies may directly interfere with the ability of B. burgdorferi to invade the salivary glands of the vector; alternately, OspA antibodies may lower the density of spirochetes within feeding ticks below a critical threshold required for initiating events linked to transmission.

Vector competence of Ixodes scapularis and Ixodes ricinus (Acari: Ixodidae) for three genospecies of Borrelia burgdorferi

The vector competence of 2 tick species, Ixodes ricinus (L.) and Ixodes scapularis Say, was determined and compared for 3 genospecies of Borrelia burgdorferi. The 3 genospecies of B. burgdorferi used in the following experiments were Borrelia burgdorferi sensu stricto (B-31 and B-31.D1 clone), Borrelia afzelii (strain Pgau. C3), and Borrelia garinii (strain VS286 and VSBP). Spirochetes from all 5 strains were inoculated intradermally into outbred mice; larval ticks of both species were subsequently fed on those mice and replete larvae were assayed for infection by culture in BSK-H media every 7 d for 4 wk. Infection frequencies in I. scapularis exposed to the 5 strains were as follows: B-31 (90%), B-31.D1 (83%), Pgau.C3 (87%), VS286 (10%), and VSBP (5%). The comparable infection frequencies for I. ricinus were B-31 (3%), B-31.D1 (3%), Pgau.C3 (90%), VS286 (5%), and VSBP (3%). Resultant nymphal I. scapularis successfully transmitted B-31, B-31,D1, Pgau.C3, and VS286 to outbred mice. I. ricinus nymphs transmitted Pgau.C3 and VS286. Both species failed to transmit strain VSBP.

Duration of immunity to reinfection with tick-transmitted Borrelia burgdorferi in naturally infected mice

The ability of naturally infected and cured mice to resist reinfection with tick-transmitted Borrelia burgdorferi was tested over a 1-year period. All of the mice were resistant to reinfection when they were challenged at 1.5 months after cure. The majority of animals were resistant to reinfection for up to 10.5 months after cure, but this resistance was lost at 1 year after cure. Both protected and unprotected animals showed a diverse array of antibodies on Western immunoblots. Protection was not associated with the killing of spirochetes in ticks, and naturally infected mice produced no antibodies to outer surface protein A (OSP A). The titers to whole Borrelia sonicate and OSP C, however, remained high throughout the 1-year study period. The levels of borreliacidal antibodies were highest in the 1.5 month-after-cure group. Natural immunity to reinfection with B. burgdorferi is limited in time, is complex, and may involve both humoral and cellular components.

Vector competence of Ixodes scapularis, I. spinipalpis, and Dermacentor andersoni (Acari:Ixodidae) in transmitting Borrelia burgdorferi, the etiologic agent of Lyme disease

This report describes the vector competence of 3 ixodid tick species, Ixodes scapularis (Say), I. spinipalpis (Nuttall), and Dermacentor andersoni (Stiles), for Borrelia burgdorferi in Colorado. The study was based on preliminary field work performed in 6 Colorado counties, where rodents and ticks were collected and assayed for the presence of B. burgdorferi. Four of the 6 counties produced 52 rodent and 39 I. spinipalpis isolates of B. burgdorferi. Two B. burgdorferi isolates were tested under laboratory conditions and found to be infective to Imperial Cancer Research Fund (ICRF) outbred mice. The 1st, a low-passage strain originating from New York (B-31, passage 6) was used as a control, and the 2nd was isolated from ear tissue of a Neotoma mexicana (Baird) (Mexican wood rat) that was trapped in Colorado. Larvae of I. scapularis, I. spinipalpis. and D. andersoni were fed on infected mice and cultured in Barbour-Stoner-Kelly media to assay for infection at 1, 2, 3, and 4 wk after repletion. The infection rates in replete larvae. were 75, 69, and 8.5%, respectively, whereas transstadial nymphal infection rates were 80, 75, and 0%, respectively. Both I. scapularis and I. spinipalpis were shown to be competent vectors that acquired the infection from the host reservoir mice and subsequently transmitted it to naive mice. Given that I. scapularis are not found in Colorado, I. spinipalpis are restricted to the nests and burrows of rodents, and because of the semiarid environment in Colorado, the risk of human contact with B. burgdorferi appears to be low.

Reactivity with a specific epitope of outer surface protein A predicts protection from infection with the Lyme disease spirochete, Borrelia burgdorferi

The response to recombinant vaccines for Lyme disease was studied to determine serum antibody levels effective in protecting against tick-transmitted infection. Data presented here demonstrate a significant correlation between antibody to an epitope on outer surface protein A (OspA) and protection against infection with Borrelia burgdorferi in canines and mice. A competitive enzyme-linked immunosorbent assay was developed to measure antibody to a site on OspA, defined by monoclonal antibody LA-2. Comparison of LA-2 titers against infection of canines and mice following vaccination and challenge established a predicted value for LA-2 titers. The statistical relationship between serum antibody levels and protection was calculated by logistic regression analysis. The statistical model predicted that an LA-2 titer of 0.32 microg equivalents (eq) per ml correlated to an 80% predicted probability of protection for both mice and dogs. This value was used to classify mice and dogs as to their protected status at the time of tick exposure. The LA-2 cutoff titer (0.32 microg eq/ml) correctly classified all dogs (n = 13) and mice (n = 44) that failed to become infected. By contrast, 20 of 22 dogs and 28 of 31 mice with titers of less than 0.32 microg eq/ml became infected. On the basis of these results, we conclude that an LA-2 titer is a reliable indicator of immune status for estimating immune protection following use of OspA-based vaccines for B. burgdorferi sensu stricto.

Outer surface protein C (OspC), but not P39, is a protective immunogen against a tick-transmitted Borrelia burgdorferi challenge: evidence for a conformational protective epitope in OspC

Outbred mice were immunized with the soluble fraction of a crude Escherichia coli lysate containing either recombinant outer surface protein C (OspC or P39 of Borrelia burgdorferi B31 (low passage). Following seroconversion, the mice were challenged with an infectious dose of B. burgdorferi B31 via the natural transmission mode of tick bite. Three mice immunized with P39 were not protected; however, all 12 of the recombinant OspC-immunized mice were protected from infection as assayed by culture and serology. Although OspC has been shown to be a protective immunogen against challenge with in vitro-cultured borrelia administered by needle, this study is the first to demonstrate OspC effectiveness against tick-borne spirochetes. Following feeding, all ticks still harbored B. burgdorferi, suggesting that the mechanism of protection is not linked to destruction of the infectious spirochete within the tick. In a separate experiment, groups of four mice were immunized with protein fractions from B. burgdorferi B31 purified by preparative gel electrophoresis in an attempt to identify potential protective antigens. Many of these mice developed high-titer-antibody responses against OspC, but curiously the mice were susceptible to B. burgdorferi infection via tick bite. These results suggest that the protective epitope(s) on OspC is heat sensitive/conformational, a finding which has implications in vaccine development.

Ability of experimentally infected chickens to infect ticks with the Lyme disease spirochete, Borrelia burgdorferi

Chickens were used as a laboratory model to determine the conditions affecting the ability of birds to infect ticks with Lyme disease spirochetes. Chicks (Gallus gallus) were exposed to 12 nymphal Ixodes scapularis at one week or three weeks of age. Xenodiagnostic larval ticks fed these birds at weekly intervals thereafter. Chicks exposed to infected nymphs at one week of age infected 87% of larvae at three weeks of age, but only infected 3% of larvae at four weeks and 0% of larvae at five weeks. Chicks exposed to nymphs at three weeks of age infected only 12% of larvae at four weeks, and 0% thereafter. Thus, experimentally infected chicks can infect larval ticks, but only for a brief interval after exposure. Young chicks are more infectious than older chickens. The immune response of infected chicks was rapid and directed against diverse antigens.

Variation in antigenicity and infectivity of derivatives of Borrelia burgdorferi, strain B31, maintained in the natural, zoonotic cycle compared with maintenance in culture

The original isolate of Borrelia burgdorferi, strain B31, can be maintained in vitro indefinitely. A number of studies have demonstrated that there are recognizable changes in the genetic composition of the spirochete after more than 60 passages. We have maintained B31 in the natural zoonotic cycle of transmission of infection between laboratory mice and laboratory-reared Ixodes ticks. To determine whether similar changes occur in the natural transmission cycle, we reisolated strain B31 from mouse skin at the fifth zoonotic cycle. This reisolated derivative had the same infectivity as the parent B31 strain, had lost the 8-kb supercoiled plasmid present in B31, and induced a gross serum antibody response indistinguishable from the B31 immune response. Analysis of antigen expression with monoclonal antibodies generated against B31, however, showed differential expression of a subset of antigens between B31 and the isolated derivative.

The Lyme disease vaccine candidate outer surface protein A (OspA) in a formulation compatible with human use protects mice against natural tick transmission of B. burgdorferi

Development of a vaccine for the Lyme disease spirochete, Borrelia burgdorferi, has focused on the bacterial lipoprotein, major outer surface protein A (OspA). With few exceptions, testing of OspA vaccines in animal models has involved challenge with needle inoculation of cultured spirochetes. Recombinant OspA proteins from two OspA divergent strains of B. burgdorferi were tested for their vaccine potential in three different strains of mice challenged with laboratory reared ticks with a high rate of B. burgdorferi infection. All formulations of the B. burgdorferi sensu stricto derived OspA vaccine protected all strains of mice when challenged by ticks infected with an OspA homologous strain of the spirochete, whereas heterologous OspA from B. afzelii did not protect. Furthermore, ticks feeding on protected mice had reduced OspA levels compared to unvaccinated controls.

Induction of an outer surface protein on Borrelia burgdorferi during tick feeding

Lyme disease spirochetes, Borrelia burgdorferi sensu lato, are maintained in zoonotic cycles involving ticks and small mammals. In unfed ticks, the spirochetes produce one outer surface protein, OspA, but not OspC. During infection in mammals, immunological data suggest that the spirochetes have changed their surface, now expressing OspC but little or no OspA. We find by in vitro growth experiments that this change is regulated in part by temperature; OspC is produced by spirochetes at 32-37 degrees C but not at 24 degrees C. Furthermore, spirochetes in the midgut of ticks that have fully engorged on mice now have OspC on their surface. Thus two environmental cues, an increase in temperature and tick feeding, trigger a major alteration of the spirochetal outer membrane. This rapid synthesis of OspC by spirochetes during tick feeding may play an essential role in the capacity of these bacteria to successfully infect mammalian hosts, including humans, when transmitted by ticks.

The Criminal Procedure (Insanity and Unfitness to Plead) Act, 1991. A case report and selected review of the legal reforms

Procedures relating to Insanity and Fitness to Plead are reviewed with special emphasis on the problems encountered with previous legislation. The introduction of the new Criminal Procedure (Insanity and Unfitness to Plead) Act 1991, on 1 January 1992, offered greater discretion in the disposal of these defendants, but fell short of many of the recommendations made by those advocating reform. As yet, too few cases have passed through the courts to highlight particular deficiencies in the unreformed parts of the Act, but the benefits are already apparent. Finally, some of the potential pitfalls of supervision and treatment orders and other disposals are discussed and an insanity case, dealt with under the new legislation, is presented.

Evaluation of the validity of the Done nomogram in the management of acute salicylate intoxication

To evaluate the validity of the Done nomogram in the management of acute adult salicylate intoxications, a retrospective review of cases at our institution was performed. The degree of severity (ie, asymptomatic, mild, moderate, or severe) as determined by plotting the serum concentration and time on the nomogram for 55 acute salicylate intoxications was compared with the degree of severity decided on by three experienced emergency physicians who based their decision on the clinical presentation of the cases and the original criteria devised by Done for each category of severity. Discordant classifications between the nomogram and the physicians provided a basis on which a predictive index for the nomogram and various subsets of cases could be determined. The calculated predictive index for the nomogram was 0.42, with the highest predictive index of 0.79 in the mild salicylate category. The nomogram tends to overpredict the severity of intoxication in the moderate and severe categories. There was no significant difference between predictive indexes of mixed versus nonmixed or enteric-coated acetylsalicylic acid versus plain acetylsalicylic acid cases, although the nomogram had a higher predictive index when used for concentrations drawn six to 12 hours after ingestion (P less than .01, Fisher's exact test). Decisions on management of an acute salicylate overdose should be based on clinical presentation and good judgment as well as the serum salicylate concentration in relation to the time of ingestion.

Prehospital blind nasotracheal intubation by paramedics

Blind nasotracheal intubation attempts by paramedics in the field were prospectively reviewed. In particular, we analyzed the frequency, success rate, complication rate, frequency of performance by each paramedic, indications, and patient outcome. Blind nasotracheal intubation was attempted in 324 patients and successful in 231. The average success rate for medical patients was 72.2% (195 of 270 attempts) and for trauma patients was 66.7% (36 of 54 attempts). This difference was not significant (P greater than .05). Even with 59.8% of the 82 participating paramedics attempting blind nasotracheal intubation less than four times over the 19-month study period, the average success rate was 71.3%. There was a significant increase in success when blind nasotracheal intubation was attempted more than three times during the study period (P less than .005). Major complications occurred in 0.9% (three) of the patients. The overall complication rate was 13% (42). The incidence of complications tended to decline with increasing paramedic frequency but did not reach statistical significance (P greater than .05). Blind nasotracheal intubation is a safe initial field airway approach in spontaneously breathing patients in whom there are no contraindications. Even with a low frequency of performance, success and complication rates are acceptable.

Canine von Willebrand factor expresses a multimeric composition similar to human von Willebrand factor

Canine von Willebrand factor (vWf) was compared to human vWf. Antisera raised against human vWf or canine vWf cross-reacted with both heterologous proteins and reactions of partial identity were seen using crossed immunoelectrophoresis. Similar patterns of multimerization were obtained for vWf from both canine and human sources using the enzyme-linked immunoelectrotransfer blot method. However, the canine protein displayed an altered electrophoretic mobility. The molecular weight of the vWf monomer was estimated by SDS-PAGE and found to be indistinguishable from that of human vWf monomer. Canine vWf is decreased in animals with clinically evident hypothyroidism and in heterozygous "carriers" of von Willebrand's disease (vWd) that display no clinical symptoms of vWd. Results expand the concept that von Willebrand's disease in dogs may be a useful model for study of vWd in humans, and that immunochemical methods established for studies of human vWf appear appropriate for studies of canine vWf.

Carboxyhemoglobin levels in patients with flu-like symptoms

Subacute carbon monoxide poisoning is commonly misdiagnosed as an influenza-like viral illness. All patients presenting to the triage nurse at University Hospital with flu-like symptoms during February 1985 were asked to give blood samples for carboxyhemoglobin determination. Fifty-five patients (10% of those eligible) with headache, dizziness, nausea, vomiting, diarrhea, weakness, general malaise, or shortness of breath were enrolled in the study. Carboxyhemoglobin levels ranged from 0 to 21%. Thirteen patients (23.6%) of this self-selected subgroup had carboxyhemoglobin levels greater than or equal to 10%. There was no statistically significant difference in carboxyhemoglobin levels between smokers and nonsmokers. More patients using wood heat had elevated carboxyhemoglobin levels than patients using any other form of heating (P less than .05). No patient with a carboxyhemoglobin level greater than or equal to 10% was diagnosed as having subacute CO poisoning by emergency physicians. Physicians must seek out the possibility of CO toxicity in patients with flu-like illness, particularly in inner-city populations during the heating months. Fundoscopy and COHb levels may be useful in selected cases to correctly diagnose patients and avoid a return to a hazardous environment with potentially fatal consequences.

Carbon monoxide poisoning

Carbon monoxide poisoning is a significant cause of illness and death. Its protean symptoms probably lead to a gross underestimation of its true incidence. Low levels of carbon monoxide aggravate chronic cardiopulmonary problems, and high levels are associated with cardiac arrhythmias and cerebral edema. Patients who survive acute poisoning are at risk of delayed neurologic sequelae. The measurement of carboxyhemoglobin levels does not reveal the tissue levels of carbon monoxide but is useful in determining therapy. Treatment includes the monitoring and management of cardiac arrhythmias and oxygenation. Hyperbaric oxygenation is beneficial, but there are currently no definite criteria for its use.