LymeNet Newsletter Volume 5 Issue 12

Volume: 5
Issue: 12
Date: 17-Dec-97

Table of Contents:

I. NY TIMES: Researchers Decode DNA Of Lyme Disease Bacterium II. WALL STREET JOURNAL: Scientists Make Lyme Disease Breakthrough III. CLIN INFEC DIS: Why is chronic Lyme borreliosis chronic? IV. CLIN INFECT DIS: Functional brain imaging and neuropsychological testing in Lyme disease. V. CLIN INFECT DIS: Invasion and cytopathic killing of human lymphocytes by spirochetes causing Lyme disease. VI. J CLIN INVEST: Simultaneous expression of Borrelia OspA and OspC and IgM response in cerebrospinal fluid in early neurologic Lyme disease. VII. About The LymeNet Newsletter

Newsletter:

*********************************************************************** * The National Lyme Disease Network * * http://www.lymenet.org/ * * LymeNet Newsletter * ***********************************************************************

IDX# Volume 5 / Number 12 / 17-DEC-97 IDX# INDEX IDX# IDX# I. NY TIMES: Researchers Decode DNA Of Lyme Disease Bacterium IDX# II. WALL STREET JOURNAL: Scientists Make Lyme Disease IDX# Breakthrough IDX# III. CLIN INFEC DIS: Why is chronic Lyme borreliosis chronic? IDX# IV. CLIN INFECT DIS: Functional brain imaging and IDX# neuropsychological testing in Lyme disease. IDX# V. CLIN INFECT DIS: Invasion and cytopathic killing of human IDX# lymphocytes by spirochetes causing Lyme disease. IDX# VI. J CLIN INVEST: Simultaneous expression of Borrelia OspA and IDX# OspC and IgM response in cerebrospinal fluid in early IDX# neurologic Lyme disease. IDX# VII. About The LymeNet Newsletter IDX#

"We took on this project because Lyme disease is very difficult to diagnose and in many instances difficult to treat. We hoped that by sequencing the bacterium's genome we could begin answering a lot of important questions."

-- Dr. Claire Fraser, the Institute of Genomic Research

I. NY TIMES: Researchers Decode DNA Of Lyme Disease Bacterium ---------------------------------------------------------------- DATE: December 10, 1997 AUTHOR: NICHOLAS WADE SOURCE: N.Y. Times News Service

Gaining a major new insight into the nature of Lyme disease, biologists have decoded the entire DNA of the bacterium that causes the infection.

Somewhat like obtaining the enemy's order of battle, the achievement yields the genetic instructions for every survival stratagem the organism has developed in the course of evolution. Biologists have a new starting point from which to develop diagnostic tests and vaccines, even though they are far from understanding all the information they have obtained.

``It is certainly very useful to have the whole book in your hand, even though you can't yet read it,'' said Dr. Alan G. Barbour of the University of California at Irvine, who first discovered how to grow the picky bacterium in the laboratory.

Dr. Benjamin J. Luft, a Lyme disease expert at the State University of New York at Stony Brook, said the new DNA sequence would be ``invaluable for the development of new therapeutics and for understanding the development of the disease.''

The DNA of the organism, known as Borrelia burgdorferi, was sequenced by Dr. Claire M. Fraser and a team of biologists at the Institute for Genomic Research in Rockville, Md., and other institutions. Their report is being published Thursday in the journal Nature.

Lyme disease, which is particularly prevalent in New York State and New England, is spread by a tick that feeds on such animals as mice, deer, dogs and humans at various stages of its life cycle. Though the disease is easily treated if antibiotics are given promptly, it can cause serious symptoms if unrecognized. A vaccine is now undergoing clinical trials, but no accurate diagnostic test is available.

Knowledge of the bacterium's full DNA sequence should help toward developing second generation vaccines, if needed, and accurate diagnostic tests. From its genetic repertoire biologists should also be able to gain a better understanding of Borrelia's complicated life cycle.

``It's very exciting for us, given the amount of money we have put into the field and the spotty progress in terms of the research,'' said James H. Handelman, executive director of the Mathers Charitable Trust of Mount Kisco, N.Y., which financed the research. The trust, which supports basic biomedical research, became interested in Lyme disease 10 years ago, in part because many of its board members had been exposed to it.

The genome of the Lyme disease organism turns out to consist of some 1,444,000 base pairs of DNA, the hereditary material. Most bacteria have genomes in the form of a single circular chromosome. Borrelia's is very unusual because it has a single linear chromosome and numerous small strips of DNA known as plasmids. Exchange of plasmids is the usual way by which bacteria transfer antibiotic resistance genes among one another.

Though few of Borrelia's genes have been directly studied, biologists can assign likely roles to many through their similarity to genes of known function from other organisms. Of the 853 genes on Borrelia's main chromosome, the roles of 59 percent have been identified. But only 16 percent of the 430 plasmid genes are familiar, Fraser's team reported.

Borrelia seems to have most of its basic housekeeping genes lined up on its main chromosome, while the plasmids carry numerous genes for making lipoproteins, substances that form the bacterium's coat. The parasite has to survive attacks by the immune systems of all its different hosts, and may do so by rapidly switching between its repertoire of lipoprotein genes so as to change the composition of its coat.

Borrelia also has many genes thought to be involved in responding to chemical cues in its environment. This is not surprising, given that the bacterium must move at the right time from the tick's stomach to its mouth parts, and that once inside its new host it must seek out various organs to lay low and avoid the immune system's attack.

Fraser said she expected that the bacterium was able to switch on one set of genes for living in its insect host and another set for living in mammals. But to her disappointment, she has not yet managed to identify any such master gene.

Fraser's team was not alone in sequencing the Borrelia genome. Biologists at the Brookhaven National Laboratory started to decode the organism's DNA in January 1996, in part to test a novel sequencing method. Fraser's team started in March 1996, using a method developed at the Institute for Genomic Research.

``It's like going jogging - you both jog faster if someone else is with you,'' Dr. John J. Dunn of the Brookhaven group said.

But Brookhaven's new method turned out not to be competitive, and Fraser's team finished first by a considerable margin.

The Lyme vaccine now being tested is based on a component of Borrelia's coat known as OspA, for outside protein A. The protein was chosen because it was the most common in laboratory cultures of Borrelia.

Biologists now know that OspA is produced only when the bacterium is living inside its insect host. As soon as Borrelia senses that it is being transferred to a mammal bitten by the tick, it switches to making another protein, OspC. By sheer luck, the OspA-based vaccine seems to be effective because it starts attacking the bacteria the instant they emerge from the tick, and before they have been able to switch coats.

Borrelia is the 11th bacterium to have its genome sequenced, and the sixth to be sequenced by the Institute for Genomic Research, which pioneered in this field in 1995.

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II. WALL STREET JOURNAL: Scientists Make Lyme Disease Breakthrough -------------------------------------------------------------------- DATE: December 11, 1997 AUTHOR: MICHAEL WALDHOLZ SOURCE: THE WALL STREET JOURNAL

Researchers have deciphered the genetic blueprint of the microbe that causes Lyme disease, a formidable achievement that scientists hope will someday lead to new treatments.

But the research has also uncovered new mysteries about the gene's makeup that ensure the search for a Lyme vaccine will still take many years of research.

Still, the discovery highlighted new techniques that are speeding up the process of cracking the genetic code of infectious agents. A gene- hunting process that until recently took several years is now taking a matter of months, offering hope for more genetic breakthroughs soon.

A Lyme disease infection, if not caught early and treated aggressively with antibiotics, can cause painful nerve damage and progressive arthritis. The ailment, most common in the Northeast and Midwest, as well as parts of California and Oregon, is caused by a tick bite, which transports the bacterium from infected deer to humans.

Lyme disease is particularly troublesome because many people miss the early signs of infection, a round skin rash and flu-like symptoms. Once the bug spreads throughout the body, it is difficult to eradicate with drugs. That's why scientists have been racing to find vaccines to protect people against the bacterium infection in the first place.

"Lyme disease has been a real enigma," said Claire Fraser, a biologist at the Institute of Genomic Research in Rockville, Md. Dr. Fraser led a large team of 38 scientists in a relatively swift 18 month effort to decode the genome, the microbe's entire set of 1,300 or so genes.

"We took on this project because Lyme disease is very difficult to diagnose and in many instances difficult to treat," she said. "We hoped that by sequencing the bacterium's genome we could begin answering a lot of important questions."

But Dr. Fraser said that identifying the genes that constitute Borrelia burgdorferi, the germ that causes Lyme disease, produced more new questions than answers. Indeed, Dr. Fraser says, many of the genes uncovered appear to produce a kind of chemical protean that scientists have never seen.

Especially disappointing, she says, is that scientists were unable to identify proteins that explain why burgdorferi can persist in humans for years even though the human body is able to mount a strong immune-system response. Thus, exploiting the new genetic data reported in today's issue of the British science journal, Nature, will likely require many more years of research.

Nonetheless, the release of the genetic code is expected to trigger a flood of research by pharmaceutical companies that have been studying the disease. Two companies, SmithKline Beecham PLC of Britain and Pasteur Merieux Connaught, a unit of Rhone-Poulenc SA, of France, are expected to market vaccines that, in clinical trials, appear to be about 80% to 90% effective. SmithKline and Pasteur Merieux have applied to the Food and Drug Administration to market the new vaccines and expect to have them available early in 1998.

Both vaccines are based on a protein that sits on the outer membrane of the bacterium. When injected into humans, the protein generates a strong response against the microbe by the body's disease fighting immune system.

Some researchers worry, however, that because the vaccine isn't completely effective in all people studied, any bacterium left in the body can cause health problems. The vaccines also don't appear to be effective in people over 65.

Scientists were impressed by the speed with which the TIGR team of researchers was able to decipher the organism's complicated genetic code. TIGR is led by Craig Venter, a former government researcher who in the past few years has helped revolutionize gene-hunting science with the development of several groundbreaking techniques.

With his help, TIGR has completed the genetic sequence of five infectious agents in the past two years. These include the sequence for Hemophilus influenzae, a microbe that can cause meningitis in children, and Heliobacter pylori, a bacterium that recently was found to be the cause of many ulcers.

Scientists note that previously only two other infectious microbes had been sequenced, each requiring about five to 10 years of research. Using its new techniques, TIGR expects to sequence six microbes next year and double that number the year after, Dr. Venter said in an interview.

Indeed, next month TIGR plans to report that it has produced the genetic code for Treponema pallidum, the bacterium that causes syphilis.

"By the end of the decade we hope to have [uncovered] the genomes for 5o infectious agents", Dr. Venter said. "With each new genome, we understand the history of the organisms, how they evolved, how they differ and what their relationship is to humans. It's a very powerful way to study and attack these pathogens."

Dr. Venter noted, for instance, that one finding from the Lyme disease research may help explain why the bacterium rides aboard ticks. The bacterium needs substances that are found inside the tick. This insight suggests that one way to fight the microbe is by blocking its ability to ingest the shared substance.

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III. CLIN INFEC DIS: Why is chronic Lyme borreliosis chronic? -------------------------------------------------------------- AUTHORS: Aberer E, Koszik F, Silberer M ORGANIZATION: Department of Dermatology, University of Graz Medical School, Austria. REFERENCE: Clin Infect Dis 1997 Jul;25 Suppl 1:S64-70 ABSTRACT:

Chronic Lyme borreliosis (CLB) can present not only in different organs but also in different patterns. Although many theories exist about the mechanisms leading to CLB, it is known that viable Borrelia burgdorferi can persist for decades and cause late skin manifestations of acrodermatitis chronica atrophicans (ACA). Thus, the immunopathogenetic findings in ACA can serve as a model for studying the chronic course of Lyme borreliosis. Recent findings indicate that the most important cell for antigen presentation, the epidermal Langerhans cell (LC), is invaded by B. burgdorferi in early Lyme borreliosis. Therefore, LCs were stained immunohistochemically with different markers to investigate their functional activity. Numbers of CD1a+ LCs were reduced in erythema migrans but normal or slightly elevated in ACA. In both diseases there was also a marked downregulation of major histocompatibility complex class II molecules on LCs, as measured by staining of human leukocyte antigen DR. This phenomenon might be a mechanism that protects against the presentation
of autoantigens and may be the cause of the impaired capacity of LCs to eliminate B. burgdorferi antigens, thus explaining why CLB is chronic.

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IV. CLIN INFECT DIS: Functional brain imaging and neuropsychological testing in Lyme disease. ---------------------------------------------------------------------- AUTHORS: Fallon BA, Das S, Plutchok JJ, Tager F, Liegner K, Van Heertum R ORGANIZATION: The New York State Psychiatric Institute, the Department of Psychiatry of Columbia University and Columbia- Presbyterian Medical Center, New York 10032, USA. REFERENCE: Clin Infect Dis 1997 Jul;25 Suppl 1:S57-63 ABSTRACT:

Differentiating neuropsychiatric Lyme disease from a primary psychiatric disorder can be a daunting task. This article describes how functional brain imaging and neuropsychological testing can be particularly valuable in helping to make diagnostic distinctions. In addition to a review of the relevance of functional imaging to neuropsychiatry in general, recent findings are presented regarding the use of single photon emission computed tomographic (SPECT) imaging in Lyme disease.

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V. CLIN INFECT DIS: Invasion and cytopathic killing of human lymphocytes by spirochetes causing Lyme disease. --------------------------------------------------------------- AUTHORS: Dorward DW, Fischer ER, Brooks DM ORGANIZATION: National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana 59840, USA REFERENCE: Clin Infect Dis 1997 Jul;25 Suppl 1:S2-8 ABSTRACT:

Lyme disease is a persistent low-density spirochetosis caused by Borrelia burgdorferi sensu lato. Although spirochetes causing Lyme disease are highly immunogenic in experimental models, the onset of specific antibody responses to infection is oftendelayed or undetectable in some patients. The properties and mechanisms mediating such immune avoidance remain obscure. To examine the nature and consequences of interactions between Lyme disease spirochetes and immune effector cells, we coincubated B. burgdorferi with primary and cultured human leukocytes. We found that B. burgdorferi actively attaches to, invades, and kills human B and T lymphocytes. Significant killing began within 1 hour of mixing. Cytopathic effects varied with respect to host cell lineage and the species, viability, and degree of attenuation of the spirochetes. Both spirochetal virulence and lymphocytic susceptibility could be phenotypically selected, thus indicating that both bacterial and host cell factors contribute to such interactions. These results suggest that invasion
and lysis of lymphocytes may constitute previously unrecognized factors in Lyme disease and bacterial pathogenesis.

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VI. J CLIN INVEST: Simultaneous expression of Borrelia OspA and OspC and IgM response in cerebrospinal fluid in early neurologic Lyme disease. ----------------------------------------------------------------- AUTHORS: Schutzer SE, Coyle PK, Krupp LB, Deng Z, Belman AL, Dattwyler R, Luft BJ ORGANIZATION: Department of Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA. [email protected] REFERENCE: J Clin Invest 1997 Aug 15;100(4):763-7 ABSTRACT:

Lyme disease is the major tick-borne disease, caused by Borrelia burgdorferi (Bb). Neurological involvement is common in all stages. In vivo expression of Bb antigens (Ags) and the immune response to them has not been well investigated in the cerebrospinal fluid (CSF). Upregulation of outer surface protein (Osp) C and concomitant downregulation of OspA before tick inoculation of the spirochete has been reported in skin and blood in animals. CSF OspA Ag in early disease suggests otherwise in CSF. Early Ag expression and IgM response in human CSF was investigated here. Paired CSF and serum was collected from 16 early, predominantly erythema migrans Lyme disease patients with neurologic problems, 13 late Lyme disease patients, and 19 other neurologic disease (OND) controls. Samples were examined for IgM reactivity to recombinant Bb-specific Osps using ELISA and immunoblot. Of 12 early Lyme disease patients with neurologic involvement with both CSF and serum IgM against OspC, 7 (58%) had IgM to OspA (n = 5) or OspB (n = 2) that was restricted to
the CSF, not serum. Overall, 12 of 16 (75%) of these early Lyme disease patients with neurologic involvement had CSF and serum IgM against OspC. Only 3 of 13 (23%) late Lyme disease patients and none of 19 OND controls had CSF IgM directed against OspC. In conclusion, in CSF, OspC and OspA can be coexpressed, and IgM response to them occurs in early Lyme disease patients with neurologic involvement. This biologic finding may also provide a discriminating marker for CNS infection in Lyme disease.

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