Vaccines and Dementia: Part I. Non-Specific Immune Boosting with BCG: History, Ligands, and Receptors

Vaccines such as Bacille Calmette-Guérin (BCG) can apparently defer dementia onset with an efficacy better than all drugs known to date, as initially reported by Gofrit et al. (PLoS One14, e0224433), now confirmed by other studies. Understanding how and why is of immense importance because it could represent a sea-change in how we manage patients with mild cognitive impairment through to dementia. Given that infection and/or inflammation are likely to contribute to the development of dementias such as Alzheimer's disease (Part II of this work), we provide a historical and molecular background to how vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents. We review early studies in which poxvirus, herpes virus, and tuberculosis (TB) infections afford cross-protection against unrelated pathogens, a concept known as 'trained immunity'. We then focus on the attenuated TB vaccine, BCG, that was introduced to protect against the causative agent of TB, Mycobacterium tuberculosis. We trace the development of BCG in the 1920 s through to the discovery, by Freund and McDermott in the 1940 s, that extracts of mycobacteria can themselves exert potent immunostimulating (adjuvant) activity; Freund's complete adjuvant based on mycobacteria remains the most potent immunopotentiator reported to date. We then discuss whether the beneficial effects of BCG require long-term persistence of live bacteria, before focusing on the specific mycobacterial molecules, notably muramyl dipeptides, that mediate immunopotentiation, as well as the receptors involved. Part II addresses evidence that immunopotentiation by BCG and other vaccines can protect against dementia development.

Vaccines and Dementia: Part II. Efficacy of BCG and Other Vaccines Against Dementia

 There is growing awareness that infections may contribute to the development of senile dementia including Alzheimer's disease (AD), and that immunopotentiation is therefore a legitimate target in the management of diseases of the elderly including AD. In Part I of this work, we provided a historical and molecular background to how vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents, culminating in the development of the tuberculosis vaccine strain Bacille Calmette-Guérin (BCG) as a treatment for some types of cancer as well as a prophylactic against infections of the elderly such as pneumonia. In Part II, we critically review studies that BCG and other vaccines may offer a measure of protection against dementia development. Five studies to date have determined that intravesicular BCG administration, the standard of care for bladder cancer, is followed by a mean ∼45% reduction in subsequent AD development in these patients. Although this could potentially be ascribed to confounding factors, the finding that other routine vaccines such as against shingles (herpes zoster virus) and influenza (influenza A virus), among others, also offer a degree of protection against AD (mean 29% over multiple studies) underlines the plausibility that the protective effects are real. We highlight clinical trials that are planned or underway and discuss whether BCG could be replaced by key components of the mycobacterial cell wall such as muramyl dipeptide. We conclude that BCG and similar agents merit far wider consideration as prophylactic agents against dementia.

Bacillus Calmette–Guérin in Immuno-Regulation of Alzheimer’s Disease

Bacillus Calmette–Guérin is frequently the treatment of choice of superficial bladder cancer. Exposing the urinary bladder of elderly patients with bladder cancer to the BCG vaccine reduced the risk of Alzheimer’s disease (AD) substantially. Vaccines against other infectious microorganisms by other vaccination methods showed a similar but a lesser effect. This suggests that immune effects on AD are antigenically non-specific, likely being a metabolic result of immune system activation, similar to that shown for Juvenile diabetes. In this mini review we point to the benefit of BCG vaccine. We then briefly highlight the pathological involvement of the immune system in the AD both, in the peripheral and the central (brain) compartments. Given the uncertain prophylactic mechanism of the BCG effect against AD we propose to take advantage of the therapeutically planned bladder exposure to BCG. Based on pathological aggregation of wrongly cleaved amyloid precursor protein (APP) resistant to the unfolded protein response (UPR) which results in amyloid beta plaques we predict that BCG may impact the UPR signaling cascade. In addition pathways of innate immunity training concerned with energy metabolism, predict capability of activated immune cells to substitute deranged astrocytes that fail to support neuronal energy metabolism. This mini review points to ways through which immune cells can mediate between BCG vaccination and AD to support the wellness of the central nervous system.

Evaluation of BCG Vaccination and Plasma Amyloid: A Prospective, Pilot Study with Implications for Alzheimer’s Disease

BCG vaccine has been used for 100 years to prevent tuberculosis. Not all countries, including the United States, adopted the initial World Health Organization recommendation to use BCG. Moreover, many Western countries that had routinely used BCG have discontinued its use. Recent population studies demonstrate lower prevalence of Alzheimer’s disease (AD) in countries with high BCG coverage. Intravesicular instillation of BCG is also used to treat bladder cancer that has not invaded the bladder muscle wall and has been shown to reduce recurrence. Several retrospective studies of bladder cancer patients demonstrated that BCG treatment was associated with a significantly reduced risk of developing AD. Plasma amyloid β assessment has become a fertile area of study for an AD biomarker that is predictive of a positive amyloid PET scan. Mass spectrometry-based plasma amyloid 42/40 ratio has proven to be accurate and robust, and when combined with age and ApoE, is shown to accurately predict current and future brain amyloid status. These parameters, amyloid 42/40 ratio, age and ApoE genotype are incorporated into an Amyloid Probability Score (APS)–a score that identifies low, intermediate or high risk of having a PET scan positive for cerebral amyloid. Community recruitment was used for this open-label pilot study. Forty-nine BCG-naïve, immunocompetent individuals completed our study: prior to BCG prime and boost, as determined by the APS, 34 had low risk (APS 0–35), 5 had intermediate risk (APS 36–57) and 10 had high risk (APS 58–100). The APS range for the participant group was 0 to 94. Follow-up plasma amyloid testing 9 months after vaccination revealed a reduction in the APS in all the risk groups: low risk group (p = 0. 37), intermediate risk group (p = 0.13) and the high-risk group (statistically significant, p = 0.016). Greater benefit was seen in younger participants and those with the highest risk. The small number of participants and the nascent status of plasma amyloid testing will rightfully temper embracement of these results. However, both the favorable direction of change after BCG as well as the utility of the APS—a valuable surrogate AD biomarker—may prompt a definitive large-scale multicenter investigation of BCG and AD risk as determined by plasma amyloid peptide ratios and APS.

Bladder Cancer Immunotherapy by BCG Is Associated with a Significantly Reduced Risk of Alzheimer's Disease and Parkinson's Disease

Bacillus Calmette–Guerin (BCG) is a live attenuated form of Mycobacterium bovis that was developed 100 years ago as a vaccine against tuberculosis (TB) and has been used ever since to vaccinate children globally. It has also been used as the first-line treatment in patients with nonmuscle invasive bladder cancer (NMIBC), through repeated intravesical applications. Numerous studies have shown that BCG induces off-target immune effects in various pathologies. Accumulating data argue for the critical role of the immune system in the course of neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). In this study, we tested whether repeated exposure to BCG during the treatment of NMIBC is associated with the risk of developing AD and PD. We presented a multi-center retrospective cohort study with patient data collected between 2000 and 2019 that included 12,185 bladder cancer (BC) patients, of which 2301 BCG-treated patients met all inclusion criteria, with a follow-up of 3.5 to 7 years. We considered the diagnosis date of AD and nonvascular dementia cases for BC patients. The BC patients were partitioned into those who underwent a transurethral resection of the bladder tumor followed by BCG therapy, and a disjoint group that had not received such treatment. By applying Cox proportional hazards (PH) regression and competing for risk analyses, we found that BCG treatment was associated with a significantly reduced risk of developing AD, especially in the population aged 75 years or older. The older population (≥75 years, 1578 BCG treated, and 5147 controls) showed a hazard ratio (HR) of 0.726 (95% CI: 0.529–0.996; p-value = 0.0473). While in a hospital-based cohort, BCG treatment resulted in an HR of 0.416 (95% CI: 0.203–0.853; p-value = 0.017), indicating a 58% lower risk of developing AD. The risk of developing PD showed the same trend with a 28% reduction in BCG-treated patients, while no BCG beneficial effect was observed for other age-related events such as Type 2 diabetes (T2D) and stroke. We attributed BCG’s beneficial effect on neurodegenerative diseases to a possible activation of long-term nonspecific immune effects. We proposed a prospective study in elderly people for testing intradermic BCG inoculation as a potential protective agent against AD and PD.

Bacillus Calmette-Guérin (BCG) therapy lowers the incidence of Alzheimer's disease in bladder cancer patients

BACKGROUND

Alzheimer's disease (AD) affects one in ten people older than 65 years. Thus far, there is no cure or even disease-modifying treatment for this disease. The immune system is a major player in the pathogenesis of AD. Bacillus Calmette-Guérin (BCG), developed as a vaccine against tuberculosis, modulates the immune system and reduces recurrence of non-muscle invasive bladder cancer. Theoretical considerations suggested that treatment with BCG may decrease the risk of AD. We tested this hypothesis on a natural population of bladder cancer patients.

METHODS AND FINDINGS

After removing all bladder cancer patients presenting with AD or developing AD within one-year following diagnosis of bladder cancer, we collected data on a total of 1371 patients (1134 males and 237 females) who were followed for at least one year after the diagnosis of bladder cancer. The mean age at diagnosis of bladder cancer was 68.1 years (SD 13.0). Adjuvant post-operative intra-vesical treatment with BCG was given to 878 (64%) of these patients. The median period post-operative follow-up was 8 years. During follow-up, 65 patients developed AD at a mean age of 84 years (SD 5.9), including 21 patients (2.4%) who had been treated with BCG and 44 patients (8.9%) who had not received BCG. Patients who had been treated with BCG manifested more than 4-fold less risk for AD than those not treated with BCG. The Cox proportional hazards regression model and the Kaplan-Meier analysis of AD free survival both indicated high significance: patients not treated with BCG had a significantly higher risk of developing AD compared to BCG treated patients (HR 4.778, 95%CI: 2.837-8.046, p = 4.08x10-9 and Log Rank Chi-square 42.438, df = 1, p = 7.30x10-11, respectively). Exposure to BCG did not modify the prevalence of Parkinson's disease, 1.9% in BCG treated patients and 1.6% in untreated (Fisher's Exact Test, p = 1).

CONCLUSIONS

Bladder cancer patients treated with BCG were significantly less likely to develop AD at any age than patients who were not so treated. This finding of a retrospective study suggests that BCG treatment might also reduce the incidence of AD in the general population. Confirmation of such effects of BCG in other retrospective studies would support prospective studies of BCG in AD.

Evolutionary Genomics and Conservation of the Endangered Przewalski's Horse

Przewalski's horses (PHs, Equus ferus ssp. przewalskii) were discovered in the Asian steppes in the 1870s and represent the last remaining true wild horses. PHs became extinct in the wild in the 1960s but survived in captivity, thanks to major conservation efforts. The current population is still endangered, with just 2,109 individuals, one-quarter of which are in Chinese and Mongolian reintroduction reserves [1]. These horses descend from a founding population of 12 wild-caught PHs and possibly up to four domesticated individuals [2-4]. With a stocky build, an erect mane, and stripped and short legs, they are phenotypically and behaviorally distinct from domesticated horses (DHs, Equus caballus). Here, we sequenced the complete genomes of 11 PHs, representing all founding lineages, and five historical specimens dated to 1878-1929 CE, including the Holotype. These were compared to the hitherto-most-extensive genome dataset characterized for horses, comprising 21 new genomes. We found that loci showing the most genetic differentiation with DHs were enriched in genes involved in metabolism, cardiac disorders, muscle contraction, reproduction, behavior, and signaling pathways. We also show that DH and PH populations split ∼45,000 years ago and have remained connected by gene-flow thereafter. Finally, we monitor the genomic impact of ∼110 years of captivity, revealing reduced heterozygosity, increased inbreeding, and variable introgression of domestic alleles, ranging from non-detectable to as much as 31.1%. This, together with the identification of ancestry informative markers and corrections to the International Studbook, establishes a framework for evaluating the persistence of genetic variation in future reintroduced populations.

Evolutionary changes in the genome of Mycobacterium tuberculosis and the human genome from 9000 years BP until modern times

The demonstration of Mycobacterium tuberculosis DNA in ancient skeletons gives researchers an insight into its evolution. Findings of the last two decades sketched the biological relationships between the various species of tubercle bacilli, the time scale involved, their possible origin and dispersal. This paper includes the available evidence and on-going research. In the submerged Eastern Mediterranean Neolithic village of Atlit Yam (9000 BP), a human lineage of M. tuberculosis, defined by the TbD1 deletion in its genome, was demonstrated. An infected infant at the site provides an example of active tuberculosis in a human with a naïve immune system. Over 4000 years later tuberculosis was found in Jericho. Urbanization increases population density encouraging M. tuberculosis/human co-evolution. As susceptible humans die of tuberculosis, survivors develop genetic resistance to disease. Thus in 18th century Hungarian mummies from Vác, 65% were positive for tuberculosis yet a 95-year-old woman had clearly survived a childhood Ghon lesion. Whole genome studies are in progress, to detect changes over the millennia both in bacterial virulence and also host susceptibility/resistance genes that determine the NRAMP protein and Killer Cell Immunoglobulin-like Receptors (KIRs). This paper surveys present evidence and includes initial findings.

Blocked bacteria escape by ATRP grafting of a PMMA shell on PVA microparticles

This paper reports on the preparation and characterization of living composites consisting of poly(vinylalcohol) (PVA) hydrogel microparticles with living bacteria and a shell of poly(methyl methacrylate) (PMMA). The grafting of the PMMA shell is accomplished in the presence of living bacteria by surface polymerization of PMMA using atom transfer radical polymerization (ATRP). The PMMA shell prevents the uncontrolled bacterial escape from the hydrogel microparticles, which otherwise marks a major problem of these composites. The encapsulation of microparticles with living bacteria by PMMA retards bacteria escape upon contact to water for >20 d. The functionality of the PMMA shell is proven both by the release of fluorescein in buffer and an altered release time of bacteria in buffer solution.

Mycobacterium tuberculosis complex lipid virulence factors preserved in the 17,000-year-old skeleton of an extinct bison, Bison antiquus

Tracing the evolution of ancient diseases depends on the availability and accessibility of suitable biomarkers in archaeological specimens. DNA is potentially information-rich but it depends on a favourable environment for preservation. In the case of the major mycobacterial pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, robust lipid biomarkers are established as alternatives or complements to DNA analyses. A DNA report, a decade ago, suggested that a 17,000-year-old skeleton of extinct Bison antiquus, from Natural Trap Cave, Wyoming, was the oldest known case of tuberculosis. In the current study, key mycobacterial lipid virulence factor biomarkers were detected in the same two samples from this bison. Fluorescence high-performance liquid chromatography (HPLC) indicated the presence of mycolic acids of the mycobacterial type, but they were degraded and could not be precisely correlated with tuberculosis. However, pristine profiles of C₂₉, C₃₀ and C₃₂ mycocerosates and C₂₇ mycolipenates, typical of the Mycobacterium tuberculosis complex, were recorded by negative ion chemical ionization gas chromatography mass spectrometry of pentafluorobenzyl ester derivatives. These findings were supported by the detection of C₃₄ and C₃₆ phthiocerols, which are usually esterified to the mycocerosates. The existence of Pleistocene tuberculosis in the Americas is confirmed and there are many even older animal bones with well-characterised tuberculous lesions similar to those on the analysed sample. In the absence of any evidence of tuberculosis in human skeletons older than 9,000 years BP, the hypothesis that this disease evolved as a zoonosis, before transfer to humans, is given detailed consideration and discussion.

Genetic characterization of Mycobacterium tuberculosis in the West Bank, Palestinian Territories

Background

The World Health Organization (WHO) declared human tuberculosis (TB) a global health emergency and launched the “Global Plan to Stop Tuberculosis” which aims to save a million lives by 2015. Global control of TB is increasingly dependent on rapid and accurate genetic typing of species of the Mycobacterium tuberculosis (MTB) complex including M. tuberculosis. The aim of this study was to identify and genetically characterize the MTB isolates circulating in the West Bank, Palestinian Territories. Genotyping of the MTB isolates from patients with pulmonary TB was carried out using two molecular genetic techniques, spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeat (MIRU-VNTR) supported by analysis of the MTB specific deletion 1 (TbD1).

Findings

A total of 17 MTB patterns were obtained from the 31 clinical isolates analyzed by spoligotyping; corresponding to 2 orphans and 15 shared-types (SITs). Fourteen SITs matched a preexisting shared-type in the SITVIT2 database, whereas a single shared-type SIT3348 was newly created. The most common spoligotyping profile was SIT53 (T1 variant), identified in 35.5 % of the TB cases studied. Genetic characterization of 22 clinical isolates via the 15 loci MIRU-VNTR typing distinguished 19 patterns. The 15-loci MIT144 and MIT145 were newly created within this study. Both methods determined the present of M. bovis strains among the isolates.

Conclusions

Significant diversity among the MTB isolates circulating in the West Bank was identified with SIT53-T1 genotype being the most frequent strain. Our results are used as reference database of the strains circulating in our region and may facilitate the implementation of an efficient TB control program.

Structural changes and cellular localization of resuscitation-promoting factor in environmental isolates of Micrococcus luteus

Dormancy among nonsporulating actinobacteria is now a widely accepted phenomenon. In Micrococcus luteus, the resuscitation of dormant cells is caused by a small secreted protein (resuscitation-promoting factor, or Rpf) that is found in "spent culture medium." Rpf is encoded by a single essential gene in M. luteus. Homologs of Rpf are widespread among the high G + C Gram-positive bacteria, including mycobacteria and streptomycetes, and most organisms make several functionally redundant proteins. M. luteus Rpf comprises a lysozyme-like domain that is necessary and sufficient for activity connected through a short linker region to a LysM motif, which is present in a number of cell-wall-associated enzymes. Muralytic activity is responsible for resuscitation. In this report, we characterized a number of environmental isolates of M. luteus, including several recovered from amber. There was substantial variation in the predicted rpf gene product. While the lysozyme-like and LysM domains showed little variation, the linker region was elongated from ten amino acid residues in the laboratory strains to as many as 120 residues in one isolate. The genes encoding these Rpf proteins have been characterized, and a possible role for the Rpf linker in environmental adaptation is proposed. The environmental isolates show enhanced resistance to lysozyme as compared with the laboratory strains and this correlates with increased peptidoglycan acetylation. In strains that make a protein with an elongated linker, Rpf was bound to the cell wall, rather than being released to the growth medium, as occurs in reference strains. This rpf gene was introduced into a lysozyme-sensitive reference strain. Both rpf genes were expressed in transformants which showed a slight but statistically significant increase in lysozyme resistance.

Molecular exploration of the first-century Tomb of the Shroud in Akeldama, Jerusalem

The Tomb of the Shroud is a first-century C.E. tomb discovered in Akeldama, Jerusalem, Israel that had been illegally entered and looted. The investigation of this tomb by an interdisciplinary team of researchers began in 2000. More than twenty stone ossuaries for collecting human bones were found, along with textiles from a burial shroud, hair and skeletal remains. The research presented here focuses on genetic analysis of the bioarchaeological remains from the tomb using mitochondrial DNA to examine familial relationships of the individuals within the tomb and molecular screening for the presence of disease. There are three mitochondrial haplotypes shared between a number of the remains analyzed suggesting a possible family tomb. There were two pathogens genetically detected within the collection of osteological samples, these were Mycobacterium tuberculosis and Mycobacterium leprae. The Tomb of the Shroud is one of very few examples of a preserved shrouded human burial and the only example of a plaster sealed loculus with remains genetically confirmed to have belonged to a shrouded male individual that suffered from tuberculosis and leprosy dating to the first-century C.E. This is the earliest case of leprosy with a confirmed date in which M. leprae DNA was detected.

Detection and molecular characterization of 9,000-year-old Mycobacterium tuberculosis from a Neolithic settlement in the Eastern Mediterranean

Background

Mycobacterium tuberculosis is the principal etiologic agent of human tuberculosis. It has no environmental reservoir and is believed to have co-evolved with its host over millennia. This is supported by skeletal evidence of the disease in early humans, and inferred from M. tuberculosis genomic analysis. Direct examination of ancient human remains for M. tuberculosis biomarkers should aid our understanding of the nature of prehistoric tuberculosis and the host/pathogen relationship.

Methodology/Principal Findings

We used conventional PCR to examine bone samples with typical tuberculosis lesions from a woman and infant, who were buried together in the now submerged site of Atlit-Yam in the Eastern Mediterranean, dating from 9250-8160 years ago. Rigorous precautions were taken to prevent contamination, and independent centers were used to confirm authenticity of findings. DNA from five M tuberculosis genetic loci was detected and had characteristics consistent with extant genetic lineages. High performance liquid chromatography was used as an independent method of verification and it directly detected mycolic acid lipid biomarkers, specific for the M. tuberculosis complex.

Conclusions/Significance

Human tuberculosis was confirmed by morphological and molecular methods in a population living in one of the first villages with evidence of agriculture and animal domestication. The widespread use of animals was not a source of infection but may have supported a denser human population that facilitated transmission of the tubercle bacillus. The similarity of the M. tuberculosis genetic signature with those of today gives support to the theory of a long-term co-existence of host and pathogen.

Mode of action of fenarimol against Leishmania spp

This paper evaluates the effects of certain herbicides on Leishmania spp., their mechanism of action, and the evolutionary origin of the relevant susceptible leishmanial targets. We demonstrated that a relatively nontoxic herbicide, fenarimol, successfully interferes with a leishmanial target, which is probably a relic of an ancient ancestor. Fenarimol impairs the function of leishmanial 14alpha-sterol demethylase, a key enzyme in the sterol biosynthetic pathway. Therefore, fenarimol or its derivatives may be candidates for development of anti-leishmanial drugs. Of the herbicides that have the capability to act as potential inhibitors of the metabolism of Leishmania spp., fenarimol was found as the most active substance against both promastigotes and amastigotes in culture. In addition, it ameliorated lesions caused by Leishmania major in mice. Light microscopy demonstrated rounding of the parasite shape. Increase of osmophilic vacuoles and autophagosomal structures were observed by transmission electron microscopy. Biochemical studies demonstrated that fenarimol inhibited sterol biosynthesis. Docking of fenarimol to the modeled catalytic binding site of 14alpha-lanosterol demethylase of L. major showed a geometrical fit. Fenarimol is stabilized via hydrophobic interactions with the residues that surround it and interactions with the heme ring. These results provide support to the hypothesis that fenarimol inhibits leishmanial sterol biosynthesis. Overall, the findings suggest an additional source of substances for development of anti-leishmanial drugs.

Attempts to revive Mycobacterium tuberculosis from 300-year-old human mummies

Environmental persistence of Mycobacterium tuberculosis is subject to speculation. However, the reality that infected postmortem tissues can be a danger to pathologists and embalmers has worrisome implications. A few experimental studies have demonstrated the organism's ability to withstand exposure to embalming fluid and formalin. Recently, a failure was reported in an attempt to resuscitate an original isolate of Robert Koch to determine the lifetime of the tubercle bacillus. The present study also considers a historical approach to determine persistence under favorable environmental conditions. It asks whether acid-fast forms observed in tissues of 300-year-old Hungarian mummies can be resuscitated. Finding organisms before the advent of antibiotics and pasteurization may yield valuable genetic information. Using various media modifications, as well as guinea pig inoculation, an attempt was made to culture these tissues for M. tuberculosis. In addition, a resuscitation-promoting factor, known to increase colony counts in high G+C bacteria, was applied to the cultures. Although an occasional PCR-positive sample was detected, no colonies of M. tuberculosis were obtained. Our results may indicate that the life span of the tubercle bacillus is less than a few hundred years, even though in the short run it can survive harsh chemical treatment.

Short Communication: Palestinian infantile visceral leishmaniasis caused by a genetic variant of Leishmania infantum belonging to a new zymodeme

The parasites causing a Palestinian case of infantile visceral leishmaniasis (IVL) and those from four dogs from the Jenin District were identified serologically, biochemically and molecular biologically as Leishmania infantum, showing dogs act as a reservoir. The strain from the human case was distinct because of its unique 200-bp kDNA-polymerase chain reaction (PCR) component in its restriction fragment length polymorphism (RFLP) profile after digestion with the endonuclease RsaI, and by the electrophoretic mobility of its malate dehydrogenase (MDH(140)), designating it the reference strain of a new zymodeme of L. infantum, MON-281.

Cutaneous leishmaniasis: The prospects for a killed vaccine

Of the various protozoal diseases for which vaccines are under development, cutaneous leishmaniasis (CL), in spite o f its chronic nature, may provide the best candidate for success. Stringent experimental models are available for both new and old world CL, human studies have been conducted for several years, and there is now considerable experience in using both attenuated and killed vaccines. In this article, Chuck Greenblatt discusses this experience, showing how it has led to current WHO-TDR plans for field trials of killed vaccines followed by virulent challenge (as used in Iran in the practice of 'leishmanization').

Co-infection of Mycobacterium tuberculosis and Mycobacterium leprae in human archaeological samples: a possible explanation for the historical decline of leprosy

Both leprosy and tuberculosis were prevalent in Europe during the first millennium but thereafter leprosy declined. It is not known why this occurred, but one suggestion is that cross-immunity protected tuberculosis patients from leprosy. To investigate any relationship between the two diseases, selected archaeological samples, dating from the Roman period to the thirteenth century, were examined for both Mycobacterium leprae and Mycobacterium tuberculosis DNA, using PCR. The work was carried out and verified in geographically separate and independent laboratories. Several specimens with palaeopathological signs of leprosy were found to contain DNA from both pathogens, indicating that these diseases coexisted in the past. We suggest that the immunological changes found in multi-bacillary leprosy, in association with the socio-economic impact on those suffering from the disease, led to increased mortality from tuberculosis and therefore to the historical decline in leprosy.

Genetic and biological diversity among populations of Leishmania major from Central Asia, the Middle East and Africa

Evidence is provided for genetic and biological variation among Leishmania major strains that correlates with their geographical origin. The host-parasite relationship also appears to be specific. Great gerbils, Rhombomys opimus, and fat sand rats, Psammomys obesus, are the main reservoir hosts in Central Asia and the Middle East, respectively. However, the Central Asian parasite failed to infect the Middle Eastern rodent host in the laboratory, and vice versa. A permissively primed intergenic polymorphic (PPIP)-PCR and a single-stranded conformation polymorphism (SSCP)-PCR exposed genetic polymorphism among 30 strains of L. major from different geographical regions. This was verified by subsequent sequencing of DNA from the same strains using four genomic targets: (a) the NADH-dehydrogenase (NADH-DH) gene, (b) the 6-phosphogluconate dehydrogenase (6PGD) gene, (c) the ribosomal internal transcribed spacers, and (d) an anonymous DNA sequence originally amplified with random primers. All the genetic markers indicated that the nine Central Asian strains were a separate homogenous genetic group. The Middle Eastern strains formed another geographical group that displayed heterogeneity corresponding with their different Middle Eastern locations. Molecular markers and host-parasite relationships confirmed that Central Asian and Middle Eastern strains are genetically and biologically distinct sub-populations of L. major. Three African strains of L. major were genetically closer to the Middle Eastern strains, and a representative one did infect fat sand rats, but they had distinct permissively primed inter-genic polymorphic PCR patterns and internal transcribed spacer 2 types.

Tuberculosis: from prehistory to Robert Koch, as revealed by ancient DNA

During the past 10 years palaeomicrobiology, a new scientific discipline, has developed. The study of ancient pathogens by direct detection of their DNA has answered several historical questions and shown changes to pathogens over time. However, ancient DNA (aDNA) continues to be controversial and great care is needed to provide valid data. Here we review the most successful application of the technology, which is the study of tuberculosis. This has provided direct support for the current theory of Mycobacterium tuberculosis evolution, and suggests areas of investigation for the interaction of M tuberculosis with its host.

Micrococcus luteus -- survival in amber

A growing body of evidence now supports the isolation of microorganisms from ancient materials. However, questions about the stringency of extraction methods and the genetic relatedness of isolated organisms to their closest living relatives continue to challenge the authenticity of these ancient life forms. Previous studies have successfully isolated a number of spore-forming bacteria from organic and inorganic deposits of considerable age whose survival is explained by their ability to enter suspended animation for extended periods of time. However, despite a number of putative reports, the isolation of non-spore-forming bacteria and an explanation for their survival have remained enigmatic. Here we describe the isolation of non-spore-forming cocci from a 120-million-year-old block of amber, which by genetic, morphological, and biochemical analyses are identified as belonging to the bacterial species Micrococcus luteus. Although comparison of 16S rRNA sequences from the ancient isolates with their modern counterparts is unable to confirm the precise age of these bacteria, we demonstrate, using complementary molecular and cell biological techniques, evidence supporting the view that these (and related modern members of the genus) have numerous adaptations for survival in extreme, nutrient-poor environments, traits that will assist in this bacteria's persistence and dispersal in the environment. The bacteria's ability to utilize succinic acid and process terpine-related compounds, both major components of natural amber, support its survival in this oligotrophic environment.

Epidemiology of visceral leishmaniasis in the Jenin District, West Bank: 1989-1998

Fifty patients from rural areas in the Jenin district of the West Bank, Palestinian Authority, were diagnosed with visceral leishmaniasis (VL) between 1989 and 1998. Forty-nine (98%) were younger than 6 years old, the youngest being 9 months. The yearly incident rate of VL in the Jenin district was highest in 1994 (11.8/100,000) and decreased to 1.5/100,000 in 1998; a mortality rate of 4% was recorded. Seventeen (5.5%) of 308 dogs from the Jenin and Ramallah districts of the West Bank were seropositive by enzyme-linked immunosorbent assay in a survey of canine leishmaniasis. Although all the leishmanial strains cultured from humans and dogs were identified as Leishmania infantum by a species-specific polymerase chain reaction, further genetic analysis by restriction fragment length polymorphism of kinetoplast DNA revealed patterns of polymorphism within isolates. The findings indicate that an active focus of potentially fatal VL exits in the Jenin district of the West Bank and that the parasite, vector, and reservoir host are found in this area. The epidemiology of VL in that vicinity follows the pattern of a predominantly infantile disease traditionally found in Middle Eastern countries, without a considerable involvement of immunocompromised adults infected with HIV virus as reported in other regions.

Distinguishing Leishmania tropica and Leishmania major in the Middle East using the polymerase chain reaction with kinetoplast DNA-specific primers

This paper reports attempts to develop a sensitive and inexpensive procedure for rapid diagnosis of cutaneous leishmaniasis at the species level using skin scrapings from patients. The presence of 3 species (Leishmania major, L. tropica and L. infantum) in Israel and the West Bank demonstrates the need for a species-specific detection method in this region. The primer pair Uni21/Lmj4 was developed on the basis of an L. major minicircle sequence but it also amplified other 'Old World' species of Leishmania. Due to species-specific differences in the size of minicircles, these primers can be used in the polymerase chain reaction to answer diagnostic and epidemiological questions.

Diversity of Microorganisms Isolated from Amber

> Abstract Claims that organisms can be cultured from amber, if substantiated, would be significant contributions to our understanding of the evolution, tenacity, and potential spread of life. Three reports on the isolation of organisms from amber have been published. Cano and Borucki recently reported the isolation of Bacillus sphaericus and Lambert et al. have described a new species designated Staphylococcus succinus from 25-40 million year old Dominican amber. These characterized organisms were phylogenetically distant from extant relatives and the Staphylococcus sp. sufficiently far removed from other extant staphylococci to be considered a new species. Here we report the culture of bacteria from Dominican and previously untested 120 million year old Israeli (Lebanese lode) amber. Twenty-seven isolates from the amber matrix have been characterized by fatty-acid profiles (FAME) and/or 16S rRNA sequencing. We also performed a terminal restriction fragment pattern (TRF) analysis of the original amber before prolonged culture by consensus primer amplification of the 16S rRNA followed by restriction enzyme digestion of the amplicons. Sample TRFs were consistent with a sparse bacterial assemblage and included at least five of the isolated organisms. Finally, we microscopically mapped the internal topography of an amber slice.http://link.springer-ny.com/link/service/journals/00248/bibs/38n1p58.html

Effective immunization of mice against cutaneous leishmaniasis using an intrinsically adjuvanted synthetic lipopeptide vaccine

Two peptides representing predicted T-cell epitopes of gp63, a major surface glycoprotein of the parasite Leishmania major, were used in vaccines tested in a murine model of cutaneous leishmaniasis. Either subcutaneous or intraperitoneal immunization in saline with a peptide representing gp63 amino acids 467-482 (p467) significantly protected CBA mice against the development of severe cutaneous lesions only when the peptide was intrinsically adjuvanted by covalently adding a lauryl-cysteine moiety (LC-p467) to its amino terminus during synthesis. In marked contrast, administration of p467 alone, cysteinyl-p467 or gp63 protein in saline resulted in some disease exacerbation. Splenic cells of LC-p467 immunized mice stimulated in vitro with LC-p467 displayed strong proliferative responses and secretion of IL-2, IFN-tau and GM-CSF (but not IL-4 and IL-10) suggesting that immunization with the lipopeptide induced the TH1 type cytokine responses associated with cell-mediated immunity. The safety, efficacy, ease of production and standardization of such lipopeptide vaccines suggest that they have significant potential for the development of vaccines for humans against leishmaniasis or other parasitic or viral diseases that require cell-mediated immunity for protection.

Sex identification of archaeological human remains based on amplification of the X and Y amelogenin alleles

Sex identification of archaeological human remains is essential for the exploration of gender differences in past populations. Traditional morphometric analyses fail to identify the gender of incomplete skeletal remains and that of immature individuals. In the present work, we have established a sensitive and reliable method, based on amplification of the single-copy amelogenin-encoding gene (AMG). The Y allele carries a small deletion in the first intron, facilitating the design of distinct X- and Y-specific polymerase chain reactions. Amplification with three primers, two of which are allele-specific, allows unambiguous identification of both X and Y chromosome signals in a single reaction, providing an internal control. For added confidence, the reaction may be performed in separate tubes for each allele. Using this method, the sex was determined from the skeletal remains of 18 individuals, including young children, out of 22 examined from periods ranging from 200 to around 8000 years ago. The state of skeletal preservation ranged from poor to good. Cortical and cranial bones, as well as teeth, were found to provide sufficiently preserved DNA. The success of retrieval of amplifiable DNA was not related either to the period or to the burial site. On the other hand, the method of DNA purification was critical. In our hands, direct DNA purification by Chelex from minute samples of bone/tooth powder gave the best results. This study demonstrates the applicability of the method for gender determination in skeletal remains from different periods.

Israeli youth and AIDS: knowledge and attitude changes among high school students following an AIDS education program

A pilot project conducted in three Jerusalem schools in 1990-91 demonstrated that medical students who had received extensive training in teaching about AIDS and its prevention were able to influence the level of knowledge and attitudes on this subject among high school students. Research findings showed moderate to low knowledge levels in a sample group of 241 Jerusalem high school students on all AIDS-related questions. The average score was (mean +/- SD) 68.9 +/- 15.4, with significant differences (P < 0.01) between boys 77.2 +/- 8.6 and girls 65.9 +/- 16.4. The principal source of knowledge on AIDS among the sample population was the electronic media, 47% stating that their knowledge of HIV/AIDS came from television. After a series of four lessons in the "The Immune System and AIDS" program, there was a significant improvement in the students' knowledge. The average score rose to 78.8 +/- 13.9 with an improvement of up to 23% in the answers to the various subgroups of questions. The program succeeded in clarifying for the students the degree of personal risk from contracting HIV, but did not affect their fear of the disease--70% of the students stated that they were afraid of being ill with AIDS. The study did not examine the students' behavioral patterns.

Clonal heterogeneity in populations of Leishmania major

Forty clones of Leishmania major were derived by direct plating from lesions and from cultures of recent isolates, followed by plating as well as by additional limit dilution in some. The parental strains originated from and represented three geographical areas in each of which a distinct electrophoretic type of the enzyme 6-phosphogluconate dehydrogenase (6PGD) is found. Each clone was characterized in terms of its virulence in Sabra mice, morphology, serotype, enzyme electrophoretic profile based on 11 enzymes, and kinetoplast DNA endonuclease restriction pattern. All the clones showed a similar virulence in the mice and similar polymorphism in fresh drops of living cultures and in Giemsa-stained preparations. Ten clones from the Jordan Valley were all serotype A1, 15 clones from the Arava were all A1Bz--confirming the mixed serological nature of parasites from this region, 11 of the 20 clones from the western Negev-eastern Sinai included a new A subserotype, and 9 were A1. Generally, the geographical separation of the 6PGD variants was upheld. Two of the Jordan Valley clones were similar to those of the western Negev. On two occasions, different enzyme types were isolated from the same individual, in one case from the same lesion. All clones from the western Negev were alike and similar to the type previously found in that region. The situation in the Arava was more complicated, since clones representative of all three regional types were found. In cases where the first two types were found, the clones and their parental strains were similar. However, one parental culture yielded three clones that resembled the reference strain for the Jordan Valley and two which resembled that of the western Negev. In one of these cases, two dissimilar clones originated from the same lesion. One aberrant clone from the western Negev was variant for nucleoside hydrolase. The kinetoplast DNA of each clone was distinct but relatively complicated, which made differentiation of these regional types difficult. However, clones from the same area displayed more similarity to each other than to those of other regions, implying a closer genetic relationship.

Leishmania major: glycolipid antigens recognized by immune human sera

Extraction of whole promastigotes with a mixture of hexane-isopropanol yielded two carbohydrate-lipid fractions immunologically active against immune sera from patients with cutaneous leishmaniasis (CL): CLF-1 and CLF-2. Thin layer chromatography (TLC) separated both fractions into eight bands labeled A-H. Four of these bands, Rf 0.19, 0.25, 0.39 and 0.48 (A, B, C and E, respectively) were recognized by antibody from patients with CL in a solid phase radioimmunoassay. Antigens were also detected by autoradiography after immunoblotting of TLC. Compound A could be labeled biosynthetically with [3H]oleic acid, [14C]galactose, [14C]mannose, [14C]glucose and [32P]phosphate. B incorporated [14C]galactose, [14C]mannose, [14C]glucose and [14C]myo-inositol. C was labeled with [14C]galactose and [14C]mannose, while E incorporated [14C]glucose, [14C]mannose, [3H]oleic acid and [14C]myoinositol. Two antigens (A and B) could be also labeled on the surface of living promastigotes using galactose oxidase and [3H]sodium borohydride. Experimental data showed that CLF-1 and CLF-2, both carbohydrate-containing fractions, had different chromatographic patterns from excreted factor (EF), a polysaccharide antigen from Leishmania. The present study characterizes glycolipid molecules from L. major promastigotes, able to stimulate the immune system from patients with CL.

Development of sandfly forms of Leishmania major in sucrose solutions

Stages of Leishmania developing in the vector include different morphs that are exposed first to ingested blood and then to sugar meals. This study sought to determine whether stages occurring in the latter medium could be induced by culturing in sugar-based media. In sucrose solutions, L. major continued to divide and multiplied by 38-46%. Paramastigotes and aflagellates are forms present in late stages of Leishmania infection in Phlebotomus papatasi. They constituted 79% of the forms in sucrose medium, but a maximum of 15% in NNN. Rate and degree of transformation varied as a function of the stage of growth of the NNN starter culture. Motility was lost in sucrose media but was retained in a mixture of sucrose and Ringer's solution. In the latter mixture, the parasites exhibited transformation as well as attachment to the substrate and morphological changes of the flagellum similar to those occurring in the sandfly vector. Parasites from sucrose medium and from P. papatasi reacted similarly, whereas those from NNN reacted differently to a monoclonal antibody. It is suggested that transformation of L. major in sucrose media resembles this process in the vector.

Leishmania major: solid phase radioimmunoassay for antibody detection in human cutaneous leishmaniasis

A radioimmunoassay for the quantitative determination of antileishmanial antibody in sera from patients suffering from cutaneous leishmaniasis was developed. The assay, using as antigen either the soluble fraction from freeze-thawed sonicated Leishmania major (LRC-L137) promastigotes or a carbohydrate-lipid containing fraction obtained by extraction with hexane-isopropanol, was shown to be sensitive and reproducible. The sera of 95 patients were examined. These were from patients with cutaneous leishmaniasis (26 from the Jordan Valley and 13 from Sinai), kala-azar (9), malaria (24), schistosomiasis (10), toxoplasmosis (5), and leprosy (8); controls were 37 normal human sera. No significant antigen dependent differences were observed using sera from cutaneous leishmaniasis patients, although differences in the immunological response were observed between the two populations of these patients. Antileishmanial activity was not detected in sera from patients with malaria, schistosomiasis, or toxoplasmosis. Although sera from leprosy patients crossreacted with the carbohydrate-lipid containing fraction, it was nevertheless more strain specific than freeze thawed sonicated L. major.

Parasite immunology and lymphocyte population dynamics

We propose that parasites use "antigenic mimicry", the presentation of host-type antigens, not merely as a disguise, but as a means of actively diverting the immune system into an ineffective mode of response that actually protects the parasites. This suggestion is the outcome of analyzing the immune system by the principle of Darwinian selection--among lymphocyte populations differing in their relative growth capacities under particular environmental conditions. In particular, it is proposed that proliferation can be uncoupled from differentiation under certain predictable conditions; and moreover, clones that proliferate for prolonged periods of time without significant maturation into effector cells may gain a selective advantage and reach prominence. This mode of "latent proliferation" is a key to self-non-self discrimination: under physiologic conditions, those T and B cells are selected that react "proliferatively" with certain classes of self-antigens, ensuring tolerance to self. We suggest that parasites which present host-type antigens generate the same kind of dynamic selection among responding lymphocytes. The hypothesis links polyclonal activation and "immunosuppression" to "antigenic mimicry", predicts "concomitant immunity" to the same parasite and suggests a pathway leading to autoimmunity. It is also amenable to testing.

Lipid and lipopolysaccharide-like antigens of Leishmania promastigotes

Extraction of whole promastigotes of Leishmania tropica major and L. donovani with a mixture of hexane and isopropanol (3:2) yielded three fractions containing immunological activity: lipids, where the activity was determined by radioimmunoassay; a lipopolysaccharide-like (LPS-like), water-soluble precipitate, where activity was determined both by radioimmunoassay and double gel diffusion, and the phenol: water extract of the lipid-free promastigotes, where activity was followed by double gel diffusion. The use of a solid state, lipid-based radioimmunoassay for detection of leishmanial antigens provided a sensitive measure of their activity with a considerable degree of species and serotype specificity. We found antibodies to leishmanial lipids in sera from immunized rabbits, convalescent mice, and human patients with confirmed cases of cutaneous leishmaniasis or kala azar. There was very little activity in normal human or animal sera. Analysis by SDS-polyacrylamide gel electrophoresis of fractions from promastigotes surface-labeled with galactose oxidase and sodium borotritiate and preliminary immunochemical characterization of the LPS-like antigen showed that it contained galactose, but otherwise differed immunologically and chemically from excreted factor (EF), the best characterized leishmanial antigen.

C-reactive protein binds leishmanial excreted factors

Excreted factors from Leishmania tropica and Leishmania donovani are precipitated by human and rabbit C-reactive protein. The reaction is calcium dependent and appears to be similar to that reported to occur between C-reactive protein and various galactans. The absence of phosphate and N-acetyl galactosamine suggests that the reaction is not the result of any similarity of the excreted factors to pneumococcal C-polysaccharide.

Interaction of aminoglycosides and ionophores in the killing of Crithidia fasciculata

Crithidia fasciculata was utilized as a prescreen to determine the antiprotozoal action of aminoglycoside antibiotics alone and in combination with surface-altering agents. Paromomycin was tested with the carrier ionophores nigericin and valinomycin, the channel ionophore gramicidin and the polyene antibiotics amphotericin B and nystatin. After exposure to the drugs in suspension, organisms were plated out to determine the survival of C. fasciculata. Killing was time dependent for both the antibiotic and the ionophore. Paromomycin action was found to be potentiated by all the surface altering agents. The aminoglycosides kanamycin, gentamycin and streptomycin were studied alone and in combination with nigericin. Synergistic effects were demonstrated both with kanamycin and gentamycin in combination with nigericin. Streptomycin was ineffective both alone and with surface-altering agents.

Phenotypic diversity of cloned lines of Leishmania major promastigotes

In vitro cultured promastigotes of virulent (V) and avirulent (A) cloned lines of Leishmania major, and the parental isolate LRC-L137, were examined with respect to morphology, cell size, growth rate, and apparent DNA content. Growth rates of all lines were comparable and both virulent (V121, LRC-L137) and avirulent parasites (A12, A52, A59) exhibited a progressive decrease in apparent DNA content with time in culture, as measured by incorporation of Hoechst Dye 33342. The four cloned lines and the parental isolate showed differences in the content of morphological variants and in the mean body length. Morphologically, there were similarities between A12 and A52 and between A59 and V121. Promastigote populations were also examined for the expression of the target antigen of a previously characterized monoclonal antibody, WIC-79.3. This antibody binds to a membrane antigen that is also present in culture supernatants of Leishmania of A1 serotype. Three different assays with culture supernatants all showed that V121, A59, and A12 were high producers with LRC-L137 and A52, low producers. Similar variation in expression of the 79.3 target antigen was detected in intact organisms of the various lines by immunofluorescence with flow cytometry. No simple correlation was found between the expression or release of the WIC-79.3 target antigen and virulence. The virulence or avirulence of all cloned lines for BALB/c mice remained stable. The data are discussed in terms of differentiation stages of L. major promastigotes and the continuing search for morphological and biochemical markers of virulence.

Leishmania tropica: protective response in C3H mice vaccinated with excreted factor crosslinked with the synthetic adjuvant, muramyl dipeptide

Excreted factor, an immunosuppressive, acidic polysaccharide released by promastigotes of Leishmania tropica major in culture, was chemically crosslinked to the synthetic adjuvant muramyl dipeptide via the bifunctional imidoester dimethyladipimidate and poly-L-lysine. This conjugate, an uncrosslinked mixture of the components, or each of the components alone were injected one to three times into different groups of 8- to 12-week-old C3H mice. The mice were challenged 2 weeks after the last injection with 2 X 10(6) promastigotes of L. t. major in the base of the tail. For the next 5 weeks, the animals were monitored for number of parasites and size of the lesion which developed at the site of the challenge. Mice receiving one intraperitoneal injection of the conjugate were partially protected against challenge. Treated animals had higher initial parasite numbers but showed a more rapid clearing of the parasites. Furthermore, the treated animals developed smaller lesions that healed quicker than did those of the control groups. Multiple injections, or injection into a footpad, rather than intraperitoneally, reduced the ability to elicit a protective response. On the other hand, muramyl dipeptide injected into a footpad was partially protective. Antibody production to excreted factor, which was measured by indirect hemagglutination of sensitized erythrocytes, was detected after challenge in mice which had received conjugate or conjugate components. A delayed hypersensitivity reaction (measured by skin testing) was not detected in any of the groups prior to challenge.

Development of topical treatment for cutaneous leishmaniasis caused by Leishmania major in experimental animals

Topical treatment, with drug-containing ointments, of cutaneous leishmaniasis caused by Leishmania major in BALB/c mice was studied. Twenty chemotherapeutic agents having potential or established antileishmanial activity were formulated in different ointment and cream bases. Only 15% paromomycin sulfate with 12% methylbenzethonium chloride, 12% benzethonium chloride, 12% cetalkonium chloride, or 12% dimethyl sulfoxide, all incorporated in white soft paraffin (United Kingdom patent application no. 2117237A), were completely effective. Topical treatment twice daily for 6 or more days caused total elimination of the parasites and healing of the lesion in all treated mice. All the other antileishmanial compounds, including sodium stibogluconate, pentamidine, amphotericin B, emetine hydrochloride, metronidazole, co-trimoxazole, allopurinol, and rifampin, either showed a slight effect on the parasites or were highly toxic to the animal host at the concentrations tested.