Prevention of Lyme disease

Lyme disease and the use of tick repellents and physical protective measures to prevent the disease are discussed. Lyme disease is a multiple-organ-system, immune-mediated inflammatory disorder transmitted by the bites of ixodid ticks infected with Borrelia burgdorferi. An individual is at greatest risk for infection when a tick has been attached to the skin for more than 24 hours. Lyme disease occurs in three stages and may affect the skin, nervous system, cardiac system, and joints. Antimicrobials used in management consist primarily of penicillins, cephalosporins, tetracyclines, and erythromycin. Tick repellents are divided into those applied to the skin and those applied to clothing. Skin repellents include N,N-diethyl-meta-toluamide (DEET), 2-ethyl-1,3-hexanediol, and dimethyl phthalate. Permethrin is by far the most effective clothing repellent. DEET plus a permethrin-containing clothing repellent offers the best overall protection. The adverse effects of repellents are minimal, but cases of hypersensitivity have been reported, especially in children. Physical measures to prevent tick bites include avoiding tick-infested areas, wearing light-colored clothing for easy identification of crawling ticks, regularly checking the body and pets for ticks, wearing protective garments and closed-toed shoes, and removing attached ticks promptly by using tweezers or forceps to apply a steady upward pull. A vaccine for the active immunization of humans against Lyme disease remains to be developed. Although antimicrobial therapy is available for persons with Lyme disease, the best approach for those who may be exposed to infected ticks is to apply topical skin or clothing repellents and to practice common-sense measures of physical protection.

Borrelia burgdorferi strain 25015: characterization of outer surface protein A and vaccination against infection

Mice vaccinated with outer surface protein A (OspA) from Borrelia burgdorferi strain N40 are protected from challenge with an intradermal syringe inoculum of B. burgdorferi strains N40, B31, and CD16. Vaccination experiments were done to determine if protection extended to strains 297 and 25015. We now show that OspA-N40 immunized mice are protected against challenge with strain 297, isolated from the cerebrospinal fluid of a patient with neuroborreliosis, but not against challenge with strain 25015, isolated from a tick in Millbrook, NY. The OspA gene from strain 25015 was therefore cloned and sequenced. The deduced OspA-25015 protein sequence differs from OspA-N40 at 40 of 273 amino acids. Furthermore, mice vaccinated with rOspA-25015 are protected from challenge with strain 25015 but not against strain N40. The results extend the usefulness of OspA as a vaccine candidate, but indicate that OspA can vary among strains of B. burgdorferi and that vaccination of mice with OspA-N40 does not protect against intradermal challenge with an inoculum of 10(4) strain 25015 spirochetes.

Long-term protection of mice from Lyme disease by vaccination with OspA

Mice vaccinated with recombinant outer surface protein A (OspA) have been shown to be protected from infection with Borrelia burgdorferi, the agent of Lyme disease, when sacrificed 14 days after challenge with an intradermal inoculum of the spirochete. To determine whether infection was not merely delayed and that protection was long-lasting, we sacrificed vaccinated mice 60, 120, and 180 days after challenge; and to determine whether vaccinated mice retained their immune state over long periods, we challenged mice with B. burgdorferi 60, 90, 120, and 150 days after vaccination. The results of both groups of experiments show that the mice remained free from infection and disease and extend the usefulness of OspA as a vaccine candidate for Lyme borreliosis.

Protection of mice from Lyme borreliosis by oral vaccination with Escherichia coli expressing OspA

Mice immunized with recombinant outer surface protein A (OspA) in Freund's adjuvant or with intraperitoneal injections of live Escherichia coli expressing OspA have been shown to be protected from infection with Borrelia burgdorferi. To investigate the efficacy of oral vaccination, C3H/He mice were inoculated with 10(8) live E. coli expressing recombinant OspA by gavage and boosted in a similar manner on days 10, 20, 30, and 40. The animals developed serum IgG antibodies to OspA by immunoblot and were protected from infection when challenged with 10(4) B. burgdorferi intradermally 14 days after the last boost. Control mice did not develop antibodies to OspA and were not protected against challenge infection. These results suggest that an oral preparation of recombinant OspA could potentially be used for vaccination.

Perspective on the development of vaccines against Lyme disease

Lyme disease, the multisystem illness caused by the tick-borne spirochaete, Borrelia burgdorferi, has emerged as a threat to public health worldwide. It is a particularly vexing problem in the United States where it is growing in range and intensity. In fact, in some hyperendemic regions of New York and New England, Lyme disease is now such a threat that it interferes with all sorts of outdoor activities, and has even led to depreciation of real estate values. Family dogs in these areas seem to have been particularly hard hit by a near epidemic of lameness caused by Lyme arthritis. Persons at high risk for infection, such as outdoor workers, campers and hikers, suburbanites with lawns to cut, and pregnant women exposed to potentially infected Ixodes ticks, are clamouring for some means of protection beyond simple behaviour modification and tick avoidance which are known not always to work. Hence, the interest in human and veterinary vaccines against Lyme disease is growing.

Recombinant outer surface protein a from Borrelia burgdorferi induces antibodies protective against spirochetal infection in mice

The outer surface protein A (OspA) of Borrelia burgdorferi was isolated in its native form from strains ZS7 and B31 and as a recombinant protein from strain ZS7. Amino acid sequence analysis of internal peptides of native OspA (strain ZS7) revealed identity with the sequence deduced from the OspA gene. Repeated immunization of C57BL/6 and C.B-17 mice with any of the three OspA structures resulted in the generation of monospecific hyperimmune sera reactive with both native and recombinant OspA. Upon transfer of immune sera specific for either native OspA (strain B31) or recombinant OspA (strain ZS7) but not of those reactive with the recombinant 41-kDa flagellin-associated antigen, severe combined immunodeficient (SCID) mice were completely protected against infection with strain ZS7. The finding that monoclonal antibodies to OspA and to OspB but not to non-outer surface spirochetal structures such as flagellin, p20, p65, and p70 conferred protection in SCID mice makes OspA (and possibly OspB) a promising candidate vaccine against Lyme disease.

Lyme disease: a proposed ecological index to assess areas of risk in the northeastern United States

BACKGROUND

Recent public awareness has resulted in a demand for information about ways to reduce the risk of acquiring Lyme disease.

METHODS

Twenty-two school properties and recreational areas within a Lyme disease endemic area of central Monmouth County, New Jersey were evaluated for risk of transmission using an ecological index on the suitability, amount, and access to Ixodes dammini habitat by target human populations and the abundance of infected adult ticks.

RESULTS

The characterization of tick habitat accurately predicted the elimination of 11 sites from concern. Of the remaining 11 sites, six were classified high risk and five as moderate risk. On-site tick surveys identified infected I. dammini adults at only four sites (three risk; one moderate risk).

CONCLUSIONS

These results indicate that the use of selected ecological parameters provides a cost-effective method to rapidly identify areas at risk for Lyme disease transmission.

Characterization of the protective antibody response to Borrelia burgdorferi in experimentally infected LSH hamsters

We show that serum obtained from normal hamsters infected with Borrelia burgdorferi can confer complete protection on irradiated recipients challenged with the Lyme spirochete. Borreliacidal activity was detected 7 days after infection, peaked at weeks 3 to 5, and thereafter decreased. Relatively high borreliacidal activity was detected in immune serum at weeks 3 and 5 of infection. The borreliacidal activity did not correlate with antibody used for the serodiagnosis of Lyme disease, which remained elevated throughout experimental infection. Our results also demonstrated that blocking antibody and antigenic variation in B. burgdorferi did not account for the decreasing titer of protective antibody. These findings indicate that protection against reinfection gradually wanes.

Lyme disease control in face of tick phobia

Lyme disease, the subject of recent public awareness and fear, not only can be controlled through medical means but also can be effectively prevented with environmental techniques and common sense safety precautions. Understanding the origin of the disease and its carriers will aid physicians in calming patient fears and reinforcing preventive measures.

Lyme disease

The rapid rate of increase in reported cases of Lyme disease exceeds that of any zoonotic disease, and the annual occurrence of cases is greater than the sum of all other tick-borne illnesses in the United States. This, in addition to the geographic spread of cases to most of the United States, has greatly heightened investigative interests in all aspects of Lyme disease and its control.

A mouse model for Borrelia burgdorferi infection: pathogenesis, immune response and protection

Viable Borrelia burgdorferi (B. burgdorferi) organisms induce a chronic infection associated with arthritis, carditis and hepatitis in severe combined immunodeficiency (scid) mice but not in most of the adult mice from the various immunocompetent inbred strains tested. Furthermore, we have found that experimental inoculation of normal mice with B. burgdorferi organisms leads to the generation of antibodies and T cells specific for various spirochetal antigens including the outer surface proteins A and B (OspA, OspB) as well as flagellin. The assumption of a protective role of the immune response during B. burgdorferi infection in mice is supported by our recent findings that passively transferred B. burgdorferi-specific immune mouse sera as well as monoclonal antibodies to OspA are able to prevent the development of the disease in scid mice. We show now that purified OspA protein both in its native and recombinant form is immunogenic and that the antibodies generated are able to confer protection to scid mice against B. burgdorferi infection.

A mouse model for Borrelia burgdorferi infection: approach to a vaccine against Lyme disease

Lyme disease is the most common vector-transmitted illness in the USA and Europe. The pathogen, Borrelia burgdorferi, causes a complex spectrum of disease that affects the skin, joints, nervous system and heart. Patients in the early stages of the disease can often be successfully treated with antibiotics but this becomes less reliable as the disease progresses. The specific immune responses that are detectable in patients with Lyme disease are not sufficient to protect against illness; a vaccine against the infectious agent is, therefore, desirable. In this article Markus M. Simon and colleagues present a mouse model of Borrelia burgdorferi infection. Their work suggests that the outer surface protein A (OspA) of Borrelia burgdorferi may be a suitable vaccine candidate.

Protection of mice against the Lyme disease agent by immunizing with recombinant OspA

Lyme borreliosis is a tick-borne illness caused by Borrelia burgdorferi. The gene for outer surface protein A (OspA) from B. burgdorferi strain N40 was cloned into an expression vector and expressed in Escherichia coli. C3H/HeJ mice actively immunized with live transformed E. coli or purified recombinant OspA protein produced antibodies to OspA and were protected from challenge with several strains of B. burgdorferi. Recombinant OspA is a candidate for a vaccine for Lyme borreliosis.