An ancestral SARS-CoV-2 vaccine induces anti-Omicron variants antibodies by hypermutation

The immune escape of Omicron variants significantly subsides by the third dose of an mRNA vaccine. However, it is unclear how Omicron variant-neutralizing antibodies develop under repeated vaccination. We analyze blood samples from 41 BNT162b2 vaccinees following the course of three injections and analyze their B-cell receptor (BCR) repertoires at six time points in total. The concomitant reactivity to both ancestral and Omicron receptor-binding domain (RBD) is achieved by a limited number of BCR clonotypes depending on the accumulation of somatic hypermutation (SHM) after the third dose. Our findings suggest that SHM accumulation in the BCR space to broaden its specificity for unseen antigens is a counterprotective mechanism against virus variant immune escape.

Distinct features of B cell receptors in neuromyelitis optica spectrum disorder among CNS inflammatory demyelinating diseases

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) stands out among CNS inflammatory demyelinating diseases (CIDDs) due to its unique disease characteristics, including severe clinical attacks with extensive lesions and its association with systemic autoimmune diseases. We aimed to investigate whether characteristics of B cell receptors (BCRs) differ between NMOSD and other CIDDs using high-throughput sequencing.

METHODS

From a prospective cohort, we recruited patients with CIDDs and categorized them based on the presence and type of autoantibodies: NMOSD with anti-aquaporin-4 antibodies, myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) with anti-myelin oligodendrocyte glycoprotein antibodies, double-seronegative demyelinating disease (DSN), and healthy controls (HCs). The BCR features, including isotype class, clonality, somatic hypermutation (SHM), and the third complementarity-determining region (CDR3) length, were analyzed and compared among the different disease groups.

RESULTS

Blood samples from 33 patients with CIDDs (13 NMOSD, 12 MOGAD, and 8 DSN) and 34 HCs were investigated for BCR sequencing. Patients with NMOSD tended to have more activated BCR features compare to the other disease groups. They showed a lower proportion of unswitched isotypes (IgM and IgD) and a higher proportion of switched isotypes (IgG), increased clonality of BCRs, higher rates of SHM, and shorter lengths of CDR3. Notably, advanced age was identified as a clinical factor associated with these activated BCR features, including increased levels of clonality and SHM rates in the NMOSD group. Conversely, no such clinical factors were found to be associated with activated BCR features in the other CIDD groups.

CONCLUSIONS

NMOSD patients, among those with CIDDs, displayed the most pronounced B cell activation, characterized by higher levels of isotype class switching, clonality, SHM rates, and shorter CDR3 lengths. These findings suggest that B cell-mediated humoral immune responses and characteristics in NMOSD patients are distinct from those observed in the other CIDDs, including MOGAD. Age was identified as a clinical factor associated with BCR activation specifically in NMOSD, implying the significance of persistent B cell activation attributed to anti-aquaporin-4 antibodies, even in the absence of clinical relapses throughout an individual's lifetime.

Accurate Diagnosis of COVID-19 from Self-Collectable Biospecimens Using Synthetic Apolipoprotein H Peptide-Coated Nanoparticle Assay

A high-throughput, accurate screening is crucial for the prevention and control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current methods, which involve sampling from the nasopharyngeal (NP) area by medical staffs, constitute a fundamental bottleneck in expanding the testing capacity. To meet the scales required for population-level surveillance, self-collectable specimens can be used; however, its low viral load has hindered its clinical adoption. Here, we describe a magnetic nanoparticle functionalized with synthetic apolipoprotein H (ApoH) peptides to capture, concentrate, and purify viruses. The ApoH assay demonstrates a viral enrichment efficiency of >90% for both SARS-CoV-2 and its variants, leading to an order of magnitude improvement in analytical sensitivity. For validation, we apply the assay to a total of 84 clinical specimens including nasal, oral, and mouth gargles obtained from COVID-19 patients. As a result, a 100% positivity rate is achieved from the patient-collected nasal and gargle samples, which exceeds that of the traditional NP swab method. The simple 12 min pre-enrichment assay enabling the use of self-collectable samples will be a practical solution to overcome the overwhelming diagnostic capacity. Furthermore, the methodology can easily be built on various clinical protocols, allowing its broad applicability to various disease diagnoses.

Association of B cell profile and receptor repertoire with the progression of Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent type of dementia. Reports have revealed that the peripheral immune system is linked to neuropathology; however, little is known about the contribution of B lymphocytes in AD. For this longitudinal study, 133 participants are included at baseline and second-year follow-up. Also, we analyze B cell receptor (BCR) repertoire data generated from a public dataset of three normal and 10 AD samples and perform BCR repertoire profiling and pairwise sharing analysis. As a result, longitudinal increase in B lymphocytes is associated with increased cerebral amyloid deposition and hyperactivates induced pluripotent stem cell-derived microglia with loss-of-function for beta-amyloid clearance. Patients with AD share similar class-switched BCR sequences with identical isotypes, despite the high somatic hypermutation rate. Thus, BCR repertoire profiling can lead to the development of individualized immune-based therapeutics and treatment. We provide evidence of both quantitative and qualitative changes in B lymphocytes during AD pathogenesis.

Optimization of peripheral blood volume for in silico reconstitution of the human B cell receptor repertoire

B cells recognize antigens via membrane‐expressed B‐cell receptors (BCR) and antibodies. Similar human BCR sequences are frequently found at a significantly higher frequency than that theoretically calculated. Patients infected with SARS‐CoV2 and HIV or with autoimmune diseases share very similar BCRs. Therefore, in silico reconstitution of BCR repertoires and identification of stereotypical BCR sequences related to human pathology have diagnostic potential. Furthermore, monitoring changes of clinically significant BCR sequences and isotype conversion has prognostic potential. For BCR repertoire analysis, peripheral blood (PB) is the most convenient source. However, the optimal human PB volume for in silico reconstitution of the BCR repertoire has not been studied in detail. Here, we sampled 5, 10, and 20 mL PB from the left arm and 40 mL PB from the right arm of two volunteers, reconstituted in silico PB BCR repertoires, and compared their composition. In both volunteers, PB sampling over 20 mL resulted in slight increases in functional unique sequences (FUSs) or almost no increase in repertoire diversity. All FUSs with a frequency above 0.08% or 0.03% in the 40 mL PB BCR repertoire were detected even in the 5 mL PB BCR repertoire from each volunteer. FUSs with a higher frequency were more likely to be found in BCR repertoires from reduced PB volume, and those coexisting in two repertoires showed a statistically significant correlation in frequency irrespective of sampled anatomical site. The correlation was more significant in higher‐frequency FUSs. These observations support the potential of BCR repertoire analysis for diagnosis.

Spatial epitranscriptomics reveals A-to-I editome specific to cancer stem cell microniches

Epitranscriptomic features, such as single-base RNA editing, are sources of transcript diversity in cancer, but little is understood in terms of their spatial context in the tumour microenvironment. Here, we introduce spatial-histopathological examination-linked epitranscriptomics converged to transcriptomics with sequencing (Select-seq), which isolates regions of interest from immunofluorescence-stained tissue and obtains transcriptomic and epitranscriptomic data. With Select-seq, we analyse the cancer stem cell-like microniches in relation to the tumour microenvironment of triple-negative breast cancer patients. We identify alternative splice variants, perform complementarity-determining region analysis of infiltrating T cells and B cells, and assess adenosine-to-inosine base editing in tumour tissue sections. Especially, in triple-negative breast cancer microniches, adenosine-to-inosine editome specific to different microniche groups is identified.

The spatial context of epitranscriptomic features in the tumour microenvironment remains poorly understood. Here, a method for transcriptomic and epitranscriptomic analysis of immunofluorescence-stained tissue, Select-seq, is applied to stem cell-like microniches in triple negative breast cancer.

Induction of Anti-Aquaporin 5 Autoantibody Production by Immunization with a Peptide Derived from the Aquaporin of Prevotella melaninogenica Leads to Reduced Salivary Flow in Mice

Sjögren's syndrome (SS) is an autoimmune disease characterized by dryness of the mouth and eyes. The glandular dysfunction in SS involves not only T cell-mediated destruction of the glands but also autoantibodies against the type 3 muscarinic acetylcholine receptor or aquaporin 5 (AQP5) that interfere with the secretion process. Studies on the breakage of tolerance and induction of autoantibodies to these autoantigens could benefit SS patients. To break tolerance, we utilized a PmE-L peptide derived from the AQP5-homologous aquaporin of Prevotella melaninogenica (PmAqp) that contained both a B cell "E" epitope and a T cell epitope. Repeated subcutaneous immunization of C57BL/6 mice with the PmE-L peptide efficiently induced the production of Abs against the "E" epitope of mouse/human AQP5 (AQP5E), and we aimed to characterize the antigen specificity, the sequences of AQP5E-specific B cell receptors, and salivary gland phenotypes of these mice. Sera containing anti-AQP5E IgG not only stained mouse Aqp5 expressed in the submandibular glands but also detected PmApq and PmE-L by immunoblotting, suggesting molecular mimicry. Characterization of the AQP5E-specific autoantibodies selected from the screening of phage display Ab libraries and mapping of the B cell receptor repertoires revealed that the AQP5E-specific B cells acquired the ability to bind to the Ag through cumulative somatic hypermutation. Importantly, animals with anti-AQP5E Abs had decreased salivary flow rates without immune cell infiltration into the salivary glands. This model will be useful for investigating the role of anti-AQP5 autoantibodies in glandular dysfunction in SS and testing new therapeutics targeting autoantibody production.

Amplification of a minimally biased antibody repertoire for in vitro display using a universal primer-based amplification method

Immune hosts are valuable sources for antibody discovery. To construct in vitro display antibody libraries from immune repertoires, singleplex or multiplex PCR amplification were employed using primers targeting multiple immunoglobulin genes. However, during this process, the B cell receptor repertoire is distorted due to interactions between multiple target genes and primers. To minimize this alternation, we devised a new method for harvesting immunoglobulin genes and tested its performance in rabbit variable heavy chain (V_H) and variable kappa light chain (V_K) genes. Double-stranded cDNA was synthesized using primers containing V/J gene-specific regions and universal sequence parts for in vitro display. V_H and V_K gene libraries were obtained through subsequent PCR amplification using primers with universal sequences. Next-generation sequencing analysis confirmed that universal PCR libraries had more diverse V_H and V_K clonotypes, and a less biased clonal distribution, than conventional singleplex or multiplex gene-specific PCR libraries.

Activity, stability, and binding capacity of β-galactosidase immobilized on electrospun nylon-6 fiber membrane

In this research, we explored various immobilized enzyme support materials, including the novel nylon-6 fiber membrane (NFM), and evaluated the increase in surface area and its effect on enzyme binding potential. We also manipulated incubation and reaction conditions and assessed the subsequent effects on activity and stability of β-galactosidase, with comparisons between various solid support materials and free (dissolved) enzyme. Nylon-6 fiber membranes were created by electrospinning and were compared with other materials as solid supports for enzyme binding. The other materials included polyvinylidene fluoride 5-kDa nanofiltration dairy membranes, nylon-6 pellets, and silica glass beads. Scanning electron microscopy revealed the large surface area of NFM, which correlated with greater enzyme activity compared with the relatively flatter surfaces of the other solid support materials. Enzyme activity was measured spectrophotometrically with the color-changing substrate o-nitrophenyl-β-d-galactopyranoside. Compared with the other solid supports, NFM had greater maximum enzyme binding potential. Across pH conditions ranging from 3.5 to 6.0 (including the optimal pH of 4.0-5.0), enzyme activity was maintained on the membrane-immobilized samples, whereas free enzyme did not maintain activity. Altering the storage temperature (4, 22, and 50°C) affected enzyme stability (i.e., the ability of the enzyme to maintain activity over time) of free and polyvinylidene fluoride membrane samples. However, NFM samples maintained stability across the varying storage temperatures. Increasing the immobilization solution enzyme concentration above the maximum enzyme binding capacity had no significant effect on enzyme stability for membrane-immobilized samples; however, both had lower mean stability than free enzyme by approximately 74%. With further development, β-galactosidase immobilized on NFM or other membranes could be used in continuous processing in the dairy industry for a combination of filtration and lactose hydrolysis-creating products that are reduced in lactose and increased in sweetness, with no requirement for "added sugars" on the nutrition label and no enzyme listed as final product ingredient.

Stereotypic neutralizing VH antibodies against SARS-CoV-2 spike protein receptor binding domain in patients with COVID-19 and healthy individuals

Stereotypic antibodies (Abs) are produced in healthy individuals by preexisting naïve B cells that have not undergone somatic hypermutation or class switching. Kim et al. have identified stereotypic neutralizing Abs (nAbs) against SARS-CoV-2 spike protein receptor binding domain (RBD) in healthy individuals and patients with COVID-19. They detected RBD-specific stereotypic variable heavy chain (V_H) Ab clonotypes composed of Ig heavy variable 3-53 (IGHV3-53) or IGHV3-66 and Ig heavy joining 6 (IGHJ6) genes in 13 of 17 patients with COVID-19. One stereotypic nAb could inhibit in vitro replication of a clinical isolate of SARS-CoV-2. These V_H clonotypes were also found in 6 of 10 healthy individuals with no evidence of exposure to SARS-CoV-2, and together, these findings provide evidence of the presence of preexisting nAbs to SARS-CoV-2.

Stereotypic antibody clonotypes exist in healthy individuals and may provide protective immunity against viral infections by neutralization. We observed that 13 of 17 patients with COVID-19 had stereotypic variable heavy chain (V_H) antibody clonotypes directed against the receptor binding domain (RBD) of SARS-CoV-2 spike protein. These antibody clonotypes were composed of immunoglobulin heavy variable 3-53 (IGHV3-53) or IGHV3-66 and immunoglobulin heavy joining 6 (IGHJ6) genes. These clonotypes included IgM, IgG3, IgG1, IgA1, IgG2, and IgA2 subtypes and had minimal somatic mutations, which suggested swift class switching after SARS-CoV-2 infection. The different IGHV chains were paired with diverse light chains resulting in binding to the RBD of SARS-CoV-2 spike protein. Human antibodies specific for the RBD can neutralize SARS-CoV-2 by inhibiting entry into host cells. We observed that one of these stereotypic neutralizing antibodies could inhibit viral replication in vitro using a clinical isolate of SARS-CoV-2. We also found that these V_H clonotypes existed in 6 of 10 healthy individuals, with IgM isotypes predominating. These findings suggest that stereotypic clonotypes can develop de novo from naïve B cells and not from memory B cells established from prior exposure to similar viruses. The expeditious and stereotypic expansion of these clonotypes may have occurred in patients infected with SARS-CoV-2 because they were already present.

Cell-Free Bacteriophage Genome Synthesis Using Low-Cost Sequence-Verified Array-Synthesized Oligonucleotides

Synthesizing engineered bacteriophages (phages) for human use has potential in various applications ranging from drug screening using a phage display to clinical use using phage therapy. However, the engineering of phages conventionally involves the use of an in vivo system that has low production efficiency because of high virulence against the host and low transformation efficiency. To circumvent these issues, de novo phage genome synthesis using chemically synthesized oligonucleotides (oligos) has increased the potential for engineering phages in a cell-free system. Here, we present a cell-free, low-cost, de novo gene synthesis technology called Sniper assembly for phage genome construction. With massively parallel sequencing of microarray-synthesized oligos, we generated and identified approximately 100 000 clonal DNA clusters in vitro and 5000 error-free ones in a cell-free environment. To demonstrate its practical application, we synthesized the Acinetobacter phage AP205 genome (4268 bp) using 65 sequence-verified DNA clones. Compared to previous reports, Sniper assembly lowered the genome synthesis cost ($0.0137/bp) by producing low-cost sequence-verified DNA.

High-throughput construction of multiple cas9 gene variants via assembly of high-depth tiled and sequence-verified oligonucleotides

Selective retrieval of sequence-verified oligonucleotides (oligos) from next-generation sequencing (NGS) flow cells, termed megacloning, promises accurate and reliable gene synthesis. However, gene assembly requires a complete collection of overlapping sense and nonsense oligos, and megacloning does not typically guarantee the complete production of sequence-verified oligos. Therefore, missing oligos must be provided via repetitive rounds of megacloning, which introduces a bottleneck for scaled-up efforts at gene assembly. Here, we introduce the concept of high-depth tiled oligo design to successfully utilize megacloned oligos for gene synthesis. Using acquired oligos from a single round of the megacloning process, we assembled 72 of 81 target Cas9-coding gene variants. We further validated 62 of these cas9 constructs, and deposited the plasmids to Addgene for subsequent functional characterization by the scientific community. This study demonstrates the utility of using sequence-verified oligos for DNA assembly and provides a practical and reliable optimized method for high-throughput gene synthesis.

Barcode-free next-generation sequencing error validation for ultra-rare variant detection

The advent of next-generation sequencing (NGS) has accelerated biomedical research by enabling the high-throughput analysis of DNA sequences at a very low cost. However, NGS has limitations in detecting rare-frequency variants (< 1%) because of high sequencing errors (> 0.1~1%). NGS errors could be filtered out using molecular barcodes, by comparing read replicates among those with the same barcodes. Accordingly, these barcoding methods require redundant reads of non-target sequences, resulting in high sequencing cost. Here, we present a cost-effective NGS error validation method in a barcode-free manner. By physically extracting and individually amplifying the DNA clones of erroneous reads, we distinguish true variants of frequency > 0.003% from the systematic NGS error and selectively validate NGS error after NGS. We achieve a PCR-induced error rate of 2.5×10⁻⁶ per base per doubling event, using 10 times less sequencing reads compared to those from previous studies.

Next generation sequencing has difficulty in detecting rare-frequency variants due to high sequencing errors. Here the authors present a barcode-free error validation method that physically extracts erroneous reads to identify true variants.

High-throughput retrieval of physical DNA for NGS-identifiable clones in phage display library

In antibody discovery, in-depth analysis of an antibody library and high-throughput retrieval of clones in the library are crucial to identifying and exploiting rare clones with different properties. However, existing methods have technical limitations, such as low process throughput from the laborious cloning process and waste of the phenotypic screening capacity from unnecessary repetitive tests on the dominant clones. To overcome the limitations, we developed a new high-throughput platform for the identification and retrieval of clones in the library, TrueRepertoire™. This new platform provides highly accurate sequences of the clones with linkage information between heavy and light chains of the antibody fragment. Additionally, the physical DNA of clones can be retrieved in high throughput based on the sequence information. We validated the high accuracy of the sequences and demonstrated that there is no platform-specific bias. Moreover, the applicability of TrueRepertoire™ was demonstrated by a phage-displayed single-chain variable fragment library targeting human hepatocyte growth factor protein.

Efficient Selection of Antibodies Reactive to Homologous Epitopes on Human and Mouse Hepatocyte Growth Factors by Next-Generation Sequencing-Based Analysis of the B Cell Repertoire

: YYB-101 is a humanized rabbit anti-human hepatocyte growth factor (HGF)-neutralizing antibody currently in clinical trial. To test the effect of HGF neutralization with antibody on anti-cancer T cell immunity, we generated surrogate antibodies that are reactive to the mouse homologue of the epitope targeted by YYB-101. First, we immunized a chicken with human HGF and monitored changes in the B cell repertoire by next-generation sequencing (NGS). We then extracted the VH gene repertoire from the NGS data, clustered it into components by sequence homology, and classified the components by the change in the number of unique VH sequences and the frequencies of the VH sequences within each component following immunization. Those changes should accompany the preferential proliferation and somatic hypermutation or gene conversion of B cells encoding HGF-reactive antibodies. One component showed significant increases in the number and frequencies of unique VH sequences and harbored genes encoding antibodies that were reactive to human HGF and competitive with YYB-101 for HGF binding. Some of the antibodies also reacted to mouse HGF. The selected VH sequences shared 98.3% identity and 98.9% amino acid similarity. It is therefore likely that the antibodies encoded by them all react to the epitope targeted by YYB-101.

Phase III trial of adjuvant capecitabine/cisplatin (XP) versus capecitabine/cisplatin/RT (XPRT) in resected gastric cancer with D2 nodal dissection (ARTIST trial): Safety analysis

4537

Background: Although the adjuvant chemoradiation therapy has gained popularity and has become the standard of care in patients with resected gastric cancer in U.S., the role of chemoradiation therapy after extended D2 dissection has been questioned. We conducted a phase III trial to compare capecitabine/cisplatin (XP) vs XP + radiotherapy (RT) in curatively D2 resected gastric cancer patients in terms of disease free survival and overall survival. Methods: Eligibility criteria were as follows: stage Ib (T1N1, T2bN0) - IV (M1 excluded), curatively ≥ D2 resected gastric adenocarcinoma. XP only: X 2,000 mg/m2/d D1∼14, CDDP 60 mg/m2 D1 repeated every 3 weeks, 6 cycles; XP + RT: X 2,000 mg/m2/d D1∼14, CDDP 60 mg/m2 D1 x 2 cycles ⋄ RT 45 Gy (25 fractions) + X 1,650 mg/m2/d during RT ⋄ X 2,000 mg/m2/d D1∼14, CDDP 60 mg/m2 D1 x 2 cycles. The primary endpoint is 3-year disease-free survival. Results: From October 2004 to April 2008, 458 patients (XP arm: 228 patients; XP/RT arm: 230 patients) were enrolled. In XP arm, 172 (75%) of 228 enrolled patients completed 6 cycles of chemotherapy. In XP + RT arm, 188 (82%) of 230 patients completed the full course of XP 2 cycles - X + RT - XP 2 cycles. Conclusions: Safety and feasibility analysis of the two arms will be reported at the meeting.

No significant financial relationships to disclose.

Work situation and work-related difficulties in stomach cancer survivors compared with the general population

9084

Background: We aimed to investigate the work situation and work-related difficulties among stomach cancer survivors compared with the general population. Methods: We enrolled 426 stomach cancer survivors diagnosed 2001 to 2003 from two hospitals and 994 members without a history of cancer selected randomly from a representative sample of Korea adults. We identified work situation and work-related difficulties in two groups using multivariate logistic regression. Results: An employment rate of stomach cancer survivors decreased from 66.2% to 53.1% at average 28 months after their diagnosis and it was lower than that of general population (63.5%). The primary reason for not-working in survivors were that they were easily fatigued (31.2%) and had limitations in physical functioning (13.0%). Examining work-related difficulties, 50.6% of survivors who were working at the time of survey reported that they were easily fatigued and 37.5% of survivors reported that their capacity of work decreased whereas only 22.4%, 10.6% of general population reported. Survivors had housework- related difficulties because they were easily fatigued (74.4%) and emotionally distressful (12.2%) whereas 58.0% and 4.0% of general population reported. Older age (adjusted odds ratio [aOR]=18.12; 95% confidence interval [CI]=6.59 to 49.81), female (aOR=5.30; 95% CI=7.37 to 31.31), low income (aOR=1.87; 95% CI=1.04 to 3.33), poor physical functioning (aOR=0.97; 95% CI=0.95 to 0.98) and total gastrectomy (aOR=2.40; 95% CI=1.26 to 4.60) were more likely to increase the likelihood of not working in stomach cancer survivors. Conclusions: Stomach cancer and its treatment had a negative impact on employment rate as previous studies with other type of cancer. Our study found that stomach cancer survivors had an experience not only work-related but also housework-related difficulties. This information on stomach survivors’ might be help to make a better plan for the intervention of stomach cancer survivors’ return to work.

No significant financial relationships to disclose.

Sero-prevalence of Taenia solium cysticercosis and Taenia solium taeniasis in California, USA

OBJECTIVES

Taenia solium Cysticercosis is a leading cause of epilepsy and neurological disability in the developing world. It is caused by ingestion of the eggs of the tapeworm, T. solium Taeniasis. The prevalence of either T. solium Cysticercosis or T. solium Taeniasis in the United States in populations at risk is poorly understood. The primary objectives of this study are to perform the first study of the sero-prevalence of T. solium Cysticercosis and T. solium Taeniasis in an at-risk community in the USA, specifically rural Southern California; identify T. solium Taeniasis positive individuals, and treat positive individuals for the tapeworm T. solium Taeniasis.

METHODS

Community based sero-prevalence study of antibodies to T. solium Cysticercosis and T. solium Taeniasis in 449 subjects living in a federally funded, predominantly Hispanic residential community; and in two migrant farm worker camps in rural Ventura County, California, USA. For this study, fingerstick blood samples were obtained. Serum immunoblots for both T. solium Cysticercosis and T. solium Taeniasis were performed.

RESULTS

The sero-prevalence of T. solium Cysticercosis was 1.8% and the sero-prevalence of T. solium Taeniasis by serum immunoblot was 1.1%. Taenia solium Cysticercosis and T. solium Taeniasis antibodies were not detected in children. The sero-prevalence of T. solium Taeniasis was highest in the migrant farm worker community. Handwashing frequency was correlated with T. solium Taeniasis sero-positivity.

CONCLUSION

The sero-prevalence of T. solium Cysticercosis and T. solium Taeniasis in this population, as detected by serum immunoblot, approximates the prevalence in some endemic areas of Latin America. Importantly, most patients likely had prior exposure, not active infection. This study establishes for the first time, the relative sero-prevalence of T. solium Cysticercosis and T. solium Taeniasis in at-risk populations in the United States.

Is there a place for the late cardioversion of atrial fibrillation? A long-term follow-up study of patients with post-thyrotoxic atrial fibrillation

AIMS

As atrial fibrillation is associated with significant mortality and morbidity, restoration of sinus rhythm is desirable. However, previous data suggest that cardioversion should be restricted to patients in whom the fibrillation is of limited duration (<1-2 years) because of high relapse rates. It may be the frequent association with cardiac disease, rather than the duration of fibrillation itself, which determined the high relapse of earlier studies. The aim of this study was to investigate rates of cardioversion, maintenance of sinus rhythm and predictors of subsequent relapse in a homogeneous group of patients without evidence of any co-existent cardiac disease.

METHODS AND RESULTS

We report on a retrospective series of 106 patients with thyrotoxicosis-induced fibrillation but no other heart disease: 87% had been in atrial fibrillation for >12 months (median duration 28.5, interquartile range 15-47 months). Cardioversion was attempted using disopyramide and then electric shock. Ninety-eight patients were successfully cardioverted: at late follow-up, 80.6+/-37 months (mean+/-SD), 67% were in sinus rhythm.

CONCLUSION

Although a relationship between the duration of fibrillation and maintenance of sinus rhythm was found, the high proportion remaining in sinus rhythm, compared with other series, suggests this influence may be less important than the presence or absence of structural heart disease.

Age-specific decrease in seroprevalence of schistosomiasis in Puerto Rico

In our previous work, we reported the first systematic, island-wide, serologic survey for schistosomiasis in Puerto Rico in 40 years. In that study, approximately 3,000 serum samples from the 76 municipalities comprising the island of Puerto Rico were tested for the detection of antibodies to S. mansoni microsomal antigens by the Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) and those positive were confirmed by an enzyme-linked immunoelectrotransfer blot (EITB). The highest EITB positivity was found in 17 municipalities, which comprised 48% of all seropositive samples. An additional finding was that 10% of the 215 EITB-positive samples were from individuals 25 years or younger and were for the most part of residents from the high seroprevalence areas. Thus, for this study we focused on 766 individuals 25 years of age or younger (45.5% males and 54.4% females), two-thirds of which were from 10 municipalities with the highest EITB seropositivity, and one-third from the 10 municipalities with the lowest EITB seropositivity found in our previous study. Of all samples, the results showed an overall FAST-ELISA positivity of 11.6%, with males similar to females (12.6 versus 10.7%, respectively). Confirmation by EITB was only 1.8%, with a males three-fold higher than females (3% versus 0.7%). When seropositivity was measured by age in five-year increments, a clear age-specific decrease in seropositivity was observed. Thus, by FAST-ELISA, 16.7% of the 21-25-year-old age group was positive, decreasing to 14.6%, 9.9%, 7.9%, and 9.3% in the 16-20-, 11-15-, 6-10-, and 1-5-year-old age groups, respectively. Confirmatory EITB showed even more impressive results: 4.7%, 2.6%, 1.2%, 0.7%, and 0% in the same age brackets. With regard to the high prevalence municipalities, only four of 10 (11 of 228 = 4.8%) had confirmatory EITB-positive samples and most were from municipalities of the Rio Grande de Loiza River basin and tributaries. The male to female positivity ratio was 4:1. Of the low prevalence municipalities, only single positive cases (by EITB) were found in three disperse municipalities. These results support the concept that there has been little transmission of S. mansoni in Puerto Rico during the first half of the 1990s and confirms anecdotal comments of local physicians who have seen virtually no new infections during the past three years. This makes the documentation of eradication of schistosomiasis from Puerto Rico feasible, a goal that should be set as being before the 100th anniversary of its discovery on the island by Isaac Gonzalez-Martinez in 1904.

Neurocysticercosis in persons with epilepsy in Medellín, Colombia. The Neuroepidemiological Research Group of Antioquia

PURPOSE

A prospective series of 643 persons with epilepsy attending a reference neurologic center in Medellín, Colombia, was examined by computed tomography (CT scan) or serology or both with the enzyme-linked immunoelectrotransfer blot assay (EITB) to assess the prevalence of Taenia solium cysticercosis.

METHODS

All presenting patients were consecutively enrolled in the study. Five hundred forty-six persons underwent cerebral CT scans; 376 of them also had serum EITB performed.

RESULTS

Prevalence of neurocysticercosis by CT scan was 13.92%. Overall prevalence of T. solium antibodies with EITB was 9.82%, but for those with late-onset epilepsy (onset after age 30 years), prevalence increased to 17.5% and 19% for those who originated from outside urban Medellín. Seroprevalence in individuals with mixed lesions (cysts and calcifications) was 88.2% and 64.10% in those with live cysts. Conversely, only 2.72% of persons with CT findings not related to neurocysticercosis had positive EITB tests.

CONCLUSIONS

Our study shows that an important proportion of individuals with epilepsy have radiologic or serologic evidence of T. solium infection, suggesting that neurocysticercosis is an important etiology for epilepsy in Colombia.

A recombinant protein from Schistosoma mansoni useful for the detection of S. mansoni and Schistosoma haematobium antibodies

A recombinant Schistosoma mansoni protein has been identified as a useful antigen for the detection of S. mansoni and Schistosoma haematobium antibodies. The purified recombinant protein, Sm22.3, was assayed using an enzyme-linked immunosorbent assay format against a battery of 491 well defined sera, including S. mansoni, S. haematobium, and Schistosoma japonicum infection sera, normal human sera, sera from 9 other parasitic infections, and sera from 2 additional infections. The sensitivity for detecting S. mansoni and S. haematobium infections with this single recombinant protein is 80.1%. The specificity is 94.8%. However, 15 of the 16 cross-reactive sera are malaria infection sera, and we have data suggesting that these malaria sera are actually recognizing an epitope on the vector-derived 6Xhistidine tag of recombinant Sm22.3. If this is the case, then, the actual specificity of the assay is 99.6%.

Geographic clustering and seroprevalence of schistosomiasis in Puerto Rico (1995)

A systematic, island-wide survey for schistosomiasis in Puerto Rico has not been conducted for more than 40 years. In 1974, a thorough survey of Boqueron de Las Piedras, a small community, showed a prevalence of 40%. No additional information on prevalence in Puerto Rico has been obtained during the ensuing 21 years. Concern for the public health of residents and visitors prompted the formation of the Bilharzia Commission in 1994 and the systematic serosurvey reported herein. Two thousand nine hundred fifty-five plasma samples from healthy donors were obtained randomly from the Red Cross in March and April 1995. Sex, resident municipalities, and age of the donors were recorded. The donors were from all but three of 79 municipalities in Puerto Rico. No sample was available from the three out island municipalities of Mona, Vieques, and Culebra. Male donors (n = 2,027) outnumbered females (n = 928) by more than 2:1, ages ranged from nine to 76 years with most (85.3%) between 19 and 51 years of age. All samples were tested with the Falcon assay screening test:enzyme-linked immunosorbent assay (FAST:ELISA) with microsomal antigens of Schistosoma mansoni. All FAST:ELISA+ samples were confirmed by enzyme-linked immunoelectrotransfer blot (EITB). Our data showed that 15.4% were FAST:ELISA+, and 10.6% were confirmed by EITB; 13.5% of the males and 4.1% of the females were EITB+. If we exclude those municipalities with fewer than five samples, the prevalence of EITB+ ranged from 0% to 38.5%, with the highest seroprevalence rates (21.1-38.5%) concentrated in 17 municipalities, which accounted for 48% of all seropositive samples. These 17 municipalities, however, contain only 18% of the total population of Puerto Rico. Two areas of high seroprevalence rates center around Jayuya (38.5%) and Naguabo (36.4%). The previously surveyed area of Boqueron is located in Las Piedras (35.3%), adjacent to Naguabo. In addition, we found 10% (21) of our total 215 donors less than 25 years of age to be EITB+ and all but two are residents of the high prevalence districts. These data strongly support the contention that schistosomiasis has been transmitted in a focal fashion during the past approximately 20 years.

Schistosomiasis in Lake Malawi

BACKGROUND

In 1992 two US Peace Corps volunteers (PCVs) developed central nervous system schistosomiasis due to infection with Schistosoma haematobium following recreational water exposure at Cape Maclear on Lake Malawi, an African lake considered by many to be free of schistosomiasis. To determine the transmission potential and risk for aquiring schistosomiasis in Lake Malawi, a cross-sectional survey of resident expatriates and visitors to Malawi was done during March and April, 1993.

METHODS

A volunteer cohort of expatriates and visitors representing a cross-section of Malawi's foregn population answered detailed questions about freshwater contact and provided blood specimens to determine the seroprevalence of S haematobium and S mansoni by ELISA and immunoblot analyses. A survey for vector snails was conducted along Lake Malawi's southwestern shore.

FINDINGS

The study population of 955 included 305 US citizens and 650 non-US foreign nationals. 303 of the study population had serological evidence of current or past schistosome infection. Seroprevalence was 32% (141/440) among expatriates whose freshwater exposure was limited to Lake Malawi; S haematobium antibodies were found in 135 of 141 (96%) seropositive specimens. Risk of seropositivity increased with the number of freshwater exposures at Lake Malawi resorts. Although many resort areas in the southwestern lake region posed a significant risk, Cape Maclear was the location most strongly associated with seropositivity (OR 2.9, 95% Cl 1.6-5.1). Schistosome-infected Bulinus globosus, the snail vector of S haematobium in Malawi, were found at Cape Maclear and other locations along the lakeshore.

INTERPRETATION

S haematobium infection is highly prevalent among expatriates and tourists in Malawi. Recreational water contact at popular resorts on Lake Malawi is the most likely source of infection. Transmission of schistosomiasis is occurring in Lake Malawi, a previously under-recognised site of transmission.

Relationship between silent thyroiditis and recurrent Graves' disease in the postpartum period

We carried out a close follow-up study of 96 episodes of postpartum hyperthyroidism, which developed in women with a history of Graves' disease. Hyperthyroidism had developed 1-6 months (mean +/- SD, 2.3 +/- 1.4) after delivery. Radioiodine uptake (RAIU) values during the thyrotoxic phase, determined after a 1-week restriction of iodine-rich diet, ranged from very low to very high (1-70%). The group with low RAIU values (group L: < 10%, n = 26) and the normal group (group N: 10-40%, n = 33) showed significantly higher urinary excretion of iodine (UI) than the high group (group H: > 40%, n = 37), and UI in group L was comparable to that in patients with silent thyroiditis. TSH binding inhibiting antibody (TBIAb) values were determined in 87 patients at the RAIU testing, and were above normal in most of them: all in group H, 68% in group N, and 52% in group L. The mean TBIAb value in group H was significantly higher than that in group N or L (P < 0.0001 for both). Fifty-one patients in group L and group N were observed without treatment. Of these, hyperthyroidism resolved spontaneously in 39 patients (76%), in whom transient hypothyroidism developed with substantial frequency. Hyperthyroidism subsequently resumed in 18 (46%) of these 39 between 4 and 9 months (mean +/- SD, 7.1 +/- 2.1) after delivery and did not resume in the other 21. RAIU values, determined again during this later phase of hyperthyroidism, were high enough to indicate Graves' hyperthyroidism in all but one patient. During the postpartum period, TBIAb values increased and then declined in the majority of the patients irrespective of the course of hyperthyroidism. Of the 21 patients who maintained euthyroidism after spontaneous resolution of hyperthyroidism, transient increase in TBIAb was observed in 14. These findings suggest that silent thyroiditis commonly develops concomitantly with the activation of Graves' disease and delays or masks the development of Graves' hyperthyroidism.

Investigation of antigenic determinants in thyroid peroxidase by synthesis of possible sequential peptides

One way to locate antigenic determinants in thyroid peroxidase (TPO) is to evaluate the binding of chemically synthesized peptides to autoantibodies. A major epitope of TPO involved in thyroid autoimmunity has been reported to be at residues 590 to 675. Therefore, we synthesized three peptides (P1, residues 603-610; P2, 615-630; and P3, 654-665) in the most antigenic part of this range, as judged by antigenicity analysis, and measured their antigenicity by enzyme-linked immunosorbent assay (ELISA). Amino groups protected with fluorenyl-methoxycarbonyl were used in the synthesis. Sera from 42 untreated patients with Hashimoto's disease and 30 untreated patients with Graves' disease were tested for binding with each peptide. In addition, 6 sera with antibodies against denatured and reduced microsomal antigen were tested. Sera obtained from 22 normal subjects were used as a control. Binding of sera from the patients with autoimmune thyroid disease to the synthetic peptides was weak, about 1% of binding to thyroid microsomes prepared from Graves' thyroid. However, the ELISA index of a mixture of P1, P2, and P3 was significantly higher in the patients with Hashimoto's disease than in the healthy subjects. For both P2 and P3, the ELISA index of the sera with antibodies against denatured and reduced TPO was higher than that of the sera from normal subjects. These results suggested 1) that the antigenic epitopes of TPO recognized by autoantibodies may be conformational and discontinuous, and 2) that antibodies against these linear portions of TPO may exist in patients with Hashimoto's disease.

Effects of iodine on thyroid status of fetus versus mother in treatment of Graves' disease complicated by pregnancy

To investigate the effect of maternal iodine therapy for Graves' disease on fetal thyroid, we examined serum free T4 (FT4) and TSH levels in the fetus vs. those in the mother. Patients who were severely thyrotoxic were not included. Cord and maternal sera were tested at delivery in 35 patients with Graves' disease treated with iodine alone during pregnancy (6-40 mg daily). At the initiation of therapy, the mothers were at 11-37 weeks gestation, and FT4 levels ranged from 28.3-65.8 pmol/L. At delivery, maternal FT4 values ranged from 9.3-42.0 pmol/L, slightly above normal in 22 of the 35 mothers and normal in the other 13. Fetal FT4 levels were above the normal range occurred significantly less often than maternal levels (2 in 35; P less than 0.001), and no fetus had FT4 below normal. In the 13 mothers with normal FT4 levels, all fetal FT4 levels were normal; the fetal TSH level was above normal in 1 and normal in the remainder. A significant correlation was found between cord and maternal FT4 levels (P less than 0.05). In 12 of the 35 mothers, FT4 levels rose after a transient fall during iodine administration. The correlation of cord FT4 and maternal FT4 was closer when these 12 cases were excluded (P less than 0.001). Neither the dose of iodine nor the duration of therapy correlated with thyroid function in fetuses or mothers. Fetal TSH binding inhibitory antibody values strongly correlated with maternal TSH binding inhibitory antibody values (P less than 0.001). These findings indicate that 1) in the treatment of hyperthyroidism due to Graves' disease, iodine seldom if ever exposes the fetus to the risk of hypothyroidism; 2) the fetal thyroid is influenced by the same stimulatory and inhibitory factors as the maternal thyroid; and 3) escape from the inhibitory effects of iodine occurs less often in fetuses than in mothers, which may account at least in part for the lower thyroid status in the fetus compared to that in the mother.

Radioimmunoassay for calcitonin gene-related peptide and its measurement in sera of patients with thyroid disease

To investigate serum levels of calcitonin gene-related peptide (CGRP), we developed a sensitive radioimmunoassay (RIA). RIA for CGRP in serum can present some problems: the serum may degradate the tracer during incubation and suppress the antigen-antibody reaction. We avoided these problems by using aprotinin and CGRP-free serum instead of a buffer for the standard curve. We detected serum CGRP in all 39 healthy subjects when CGRP-free serum was not used for the standard curve, but 34 of these subjects had serum CGRP levels below the detection limit (less than 80 pmol/l) when CGRP-free serum was used for the standard curve. We defined the normal range for serum CGRP as below 100.8 pmol/l, which was the maximum level found in the healthy subjects. We studied serum levels of this peptide in patients with thyroid diseases, because the thyroid may be one origin of circulating CGRP. Four of 10 patients with medullary thyroid carcinoma had elevated serum levels of CGRP. Seven of 24 patients with subacute thyroiditis had elevated serum levels of CGRP, but at least one year after clinical recovery, CGRP was undetectable in all. Seven of the 37 patients with hypothyroidism had elevated serum levels of CGRP. None of the patients with hyperthyroidism, adenomatous goiter, thyroid adenoma, or thyroid carcinoma had elevated serum CGRP levels. It is necessary to use a standard curve obtained by the addition of aprotinin and CGRP-free serum to the assay standards to measure serum CGRP levels. Some patients with subacute thyroiditis, hypothyroidism, or medullary thyroid carcinoma had elevated serum CGRP levels.

Thyroid microsomal antigen in Graves' thyroid is not different from that in normal thyroid

Differences from normal in microsomal antigen (M-Ag) may be involved in the development of autoimmune thyroid disease. We compared the M-Ag in Graves' thyroid immunologically and biochemically to that in normal thyroid. The concentration of M-Ag, measured with an enzyme-linked immunosorbent assay, was significantly greater in the Graves' microsomes than in normal microsomes. Binding of a patient's microsomal antibody to Graves' microsomes was completely inhibited when the serum was first incubated with normal thyroid microsomes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western blotting were done with a monoclonal antibody to denatured M-Ag. In both Graves' and normal thyroids, M-Ag existed as 107-, 101-, and 95-kDa peptides. After incubation with V8 protease, the residual antigenic peptide had a molecular weight of less than 60,000 and after incubation with trypsin, 95- and 87-kDa peptides and several smaller antigenic peptides were found. There were no significant differences in the pattern of normal and Graves' microsomes after digestion. Two-dimensional gel electrophoresis of Graves' microsomes showed that the isoelectric point for the 107-kDa peptide was at pH 7.2; that for the 101-kDa peptide was at pH 6.2, and that for the 95-kDa peptide was at 6.5. These values were not different from those observed for normal microsomes. These results indicate that M-Ag in Graves' thyroid does not differ from that in normal thyroid, and that microsomal antibodies in autoimmune thyroid disease probably do no arise from differences in the antigen.

Why no simple relationship between thyroid peroxidase activity-inhibiting immunoglobulins and thyroid function in autoimmune thyroid disease?

We have reported that some anti-thyroid peroxidase antibodies inhibit the activity of thyroid peroxidase in vitro. These thyroid peroxidase activity-inhibiting immunoglobulins seem to inhibit thyroid function in some patients, but the relationship between thyroid peroxidase activity-inhibiting immunoglobulins and thyroid function is not simple. We designed this study to explore this lack of a simple relationship. We stained immunoglobulin G deposits by immunofluorescence staining or the peroxidase-antiperoxidase method, and stained endogenous thyroid peroxidase activity by enzyme histochemistry in thyroid sections. When cryostat thyroid sections were incubated with thyroid peroxidase activity-inhibiting immunoglobulins, immunoglobulin G deposits were seen as lines of stain on the apical border and as intracellular staining, and endogenous thyroid peroxidase activity was inhibited. In paraffin-embedded thyroid sections from 5 Hashimoto's patients and 6 Graves' patients, immunoglobulin G deposits were not found on the apical border of the follicular epithelium. In frozen thyroid sections from 22 Graves' patients, no clear deposits of immunoglobulin G on this apical border were seen. In organ-cultured thyroid slices incubated with thyroid peroxidase activity-inhibiting immunoglobulins, endogenous thyroid peroxidase activity was not inhibited. In conclusion, thyroid peroxidase activity-inhibiting immunoglobulins may reach its antigen only with difficulty. This is one of the reasons why no simple relationship is observed between thyroid peroxidase activity-inhibiting immunoglobulins and thyroid function.

Efficacy of disopyramide in conversion and prophylaxis of post-thyrotoxic atrial fibrillation

Rhythm conversion in patients with post-thyrotoxic atrial fibrillation (AF) has been performed with disopyramide in order to evaluate the conversion rate and to test its effect on the maintenance of sinus rhythm after cardioversion. The duration of AF ranged from 9 to 122 months (mean 31.8 months). Of 81 patients, 12 (15%) with relatively short duration AF were converted to sinus rhythm with disopyramide. The remaining 69 patients required DC cardioversion, which restored sinus rhythm in 58 patients. The 58 DC-converted patients were divided into two groups: a disopyramide group (D group) and a non-disopyramide group (non-D group). The D group received disopyramide 300 mg per day for 3 months after DC cardioversion and the non-D group did not receive anti-arrhythmic drugs. During the early observation period, only one patient relapsed in the D group into AF, but 5 successive patients in the non-D group reverted to AF, forcing discontinuation of the non-D protocol. A second DC cardioversion performed on 3 of those 5 patients was followed by maintenance therapy with disopyramide 300 mg per day, and they remained in sinus rhythm. With the inclusion of those three subjects, sinus rhythm was still present in 44 of the total of 58 patients converted by DC (76%) at the time of follow-up (64 months). Thus, disopyramide was effective in rhythm conversion and it was essential for the maintenance of sinus rhythm after cardioversion in patients with post-thyrotoxic AF.