Viral shedding and viraemia of Andes virus during acute hantavirus infection: a prospective study

BACKGROUND

Andes virus (ANDV) is a zoonotic Orthohantavirus leading to hantavirus cardiopulmonary syndrome. Although most transmissions occur through environmental exposure to rodent faeces and urine, rare person-to-person transmission has been documented, mainly for close contacts. This study investigates the presence and infectivity of ANDV in body fluids from confirmed cases and the duration of viraemia.

METHODS

In this prospective study, 131 participants with confirmed ANDV infection were enrolled in Chile in a prospective study between 2008 and 2022. Clinical samples (buffy coat, plasma, gingival crevicular fluid [GCF], saliva, nasopharyngeal swabs [NPS], and urine) were collected weekly for 3 weeks together with clinical and epidemiological data. Samples were categorised as acute or convalescent (up to and after 16 days following onset of symptoms). Infectivity of positive fluids was assessed after the culture of samples on Vero E6 cells and use of flow cytometry assays to determine the production of ANDV nucleoprotein.

FINDINGS

ANDV RNA was detected in 100% of buffy coats during acute phase, declining to 95% by day 17, and to 93% between days 23-29. ANDV RNA in GCF and saliva decreased from 30% and 12%, respectively, during the acute phase, to 12% and 11% during the convalescent phase. Successful infectivity assays of RT-qPCR-positive fluids, including GCF, saliva, NPS, and urine, were observed in 18 (42%) of 43 samples obtained during the acute phase of infection. After re-culture, the capacity to infect Vero E6 cells was maintained in 16 (89%) of 18 samples. Severity was associated with the presence of ANDV RNA in one or more fluids besides blood (odds ratio 2·58 [95% CI 1·42-5·18]).

INTERPRETATION

ANDV infection is a systemic and viraemic infection, that affects various organs. The presence of infectious particles in body fluids contributes to our understanding of potential mechanisms for person-to-person transmission, supporting the development of preventive strategies. Detection of ANDV RNA in additional fluids at hospital admission is a predictor of disease severity.

FUNDING

None.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Hypervirulent Strains of Neisseria meningitidis and Clinical Manifestations in Children With Invasive Meningococcal Disease

BACKGROUND

Hypervirulent clonal complex (cc) have been associated with higher incidence and case fatality rate of invasive meningococcal disease (IMD). The aim of this study was to describe the clinical manifestations of the hypervirulent cc of meningococcus in children.

METHODS

Retrospective study in patients hospitalized by IMD microbiologically confirmed at three children's tertiary health care centers in Santiago, Chile, between 2010 and 2018. Demographic, clinical information and determination of the cc and factor H binding protein (fHbp) alleles were performed.

RESULTS

In total 93 cases were evaluated, sequence typing was available for 91 cases, and 87 (95.6%) had a cc assigned; 63.7% were MenW and 31.8% MenB. The median age was 9 months, 67% were male and 18.7% had any comorbidity. A 26.4% presented neurological deficit, 25.3% petechiae and 20% diarrhea. Sixty-seven percent were admitted to the pediatric intensive care unit (PICU) and the case fatality rate was 9.9%. Regarding cc and fHbp alleles, ST11, ST41/44 and allele 22 were the most frequently identified, with 63.7%, 19.8% and 72.5%, respectively. We found statistically significant differences between the cc and presence of petechiae, diagnosis of meningococcemia plus meningitis, admission and days in PICU and advanced support. Allele 22 for fHbp was associated with the absence of petechiae, low suspicion of IMD, less diagnosis of meningitis+meningococcemia, PICU admission, advanced support and adrenal insufficiency.

CONCLUSION

Epidemiological and microbiological surveillance of IMD should integrate clinical and laboratory components, including molecular and genetic characterization, to enrich the dynamic understanding of the clinical evolution of IMD.

[Molecular detection of gastrointestinal pathogens among children under 5 years old with diarrhea in a hospital center for rotavirus sentinel surveillance in Chile]

BACKGROUND

Infectious diarrhea is still a major problem in public health, especially in children under 5 years of age. The identification of the etiologic agent is important for the clinical management of the diarrhea episode and, from the epidemiological point of view, to implement control measures.

AIM

To determine the presence of gastrointestinal pathogens in children under five years of age with diarrhea in a Chilean rotavirus surveillance center.

METHODS

Observational study in children under five years of age who were hospitalized for diarrhea at the Dr. Luis Calvo Mackenna Hospital from December 2015 to December 2019. Molecular detection was performed using the FilmArray gastrointestinal (FilmArray GI®) panel.

RESULTS

We analyzed 493 diarrheal stool samples of children, 427 samples (87%) were positive and 66 samples (13%) were negative. Of positive samples, 174 samples (41%) and 253 samples (59%) were positive for one or more pathogen, respectively. In children under one year and the group between one and four years there was a predominance of infections caused by enteric virus. Rotavirus and norovirus were the most common virus in both age groups. The most frequent bacteria were EPEC (27%), C. difficile (17%), EAEC (14%) and Campylobacter (9%). In parasites, Giardia lamblia and Cryptosporidium were identified, in 3% and 1% of the total samples, respectively.

CONCLUSIONS

The molecular detection system used allowed an increase in the detection of enteropathogens in children under five years of age. The information generated by this type of surveillance could help to characterize the episodes of diarrhea in the population and might be a tool to technically advise the authorities in the decision-making process for the implementation of control measures.

Comparison of VSV Pseudovirus and Focus Reduction Neutralization Assays for Measurement of Anti-Andes orthohantavirus Neutralizing Antibodies in Patient Samples

Andes orthohantavirus (ANDV) is the etiologic agent of hantavirus cardiopulmonary syndrome (HCPS), which has a case fatality rate around 35%, with no effective treatment or vaccine available. ANDV neutralizing antibody (NAb) measurements are important for the evaluation of the immune response following infection, vaccination, or passive administration of investigational monoclonal or polyclonal antibodies. The standard assay for NAb measurement is a focus reduction neutralization test (FRNT) featuring live ANDV and must be completed under biosafety level (BSL)-3 conditions. In this study, we compared neutralization assays featuring infectious ANDV or vesicular stomatitis virus (VSV) pseudovirions decorated with ANDV glycoproteins for their ability to measure anti-ANDV NAbs from patient samples. Our studies demonstrate that VSV pseudovirions effectively measure NAb from clinical samples and have greater sensitivity compared to FRNT with live ANDV. Importantly, the pseudovirus assay requires less labor and sample materials and can be conducted at BSL-2.

A Multicenter Study To Evaluate Ceftaroline Breakpoints: Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 Lineage

Ceftaroline (CPT) is a broad-spectrum agent with potent activity against methicillin-resistant Staphylococcus aureus (MRSA). The sequence type 5 (ST5) Chilean-Cordobés clone, associated with CPT nonsusceptibility, is dominant in Chile, a region with high rates of MRSA infections. Here, we assessed the in vitro activity of CPT against a collection of MRSA isolates collected between 1999 and 2018 from nine hospitals (n = 320) and community settings (n = 41) in Santiago, Chile, and evaluated performance across testing methodologies. We found that our hospital-associated isolates exhibited higher CPT MIC distributions (MIC50 and MIC90 of 2 mg/liter) than the community isolates (MIC50 and MIC90 of 0.5 mg/liter), a finding that was consistent across time and independent of the culture source. High proportions (64%) of isolates were CPT nonsusceptible despite the absence of CPT use in Chile. Across methodologies, the Etest underestimated the MIC relative to the gold standard broth microdilution (BMD) test (MIC50 and MIC90 of 1 and 1.5 mg/liter, respectively). There was low (∼51%) categorical agreement (CA) between Etest and BMD results across CLSI and EUCAST breakpoints. The recent revision of CLSI guidelines abolished "very major error" (VME) from the previous guidelines (81%), which perform similarly to the EUCAST guidelines. The level of concordance between CLSI and EUCAST for BMD testing and Etest was >95%. Disk diffusion performed poorly relative to BMD under CLSI (CA, 55%) and EUCAST (CA, 36%) guidelines. Comparison of EUCAST to CLSI for disk diffusion (with EUCAST used as the reference) showed low agreement (CA, 25%; VME, 70%). In summary, CPT-nonsusceptible MRSA are dominant in clinical settings in Chile. Our results provide data to support the reevaluation of CPT breakpoints and to improve agreement across methodologies and agencies.

Yellow fever vaccination for Chilean tourists visiting Brazil. Practical considerations

Due to the recent yellow fever outbreak affecting the costal region of Brazil, including main touristic destinations, there is a high demand of yellow fever vaccination. This publication addresses the most relevant practical issues regarding this vaccine for tourists visiting Brazil and aims to serve as a guideline for non-expert physicians in Chile and elsewhere.

Laboratory exposure to Coccidioides: lessons learnt in a non-endemic country

Coccidioides is a primary pathogenic fungus, which infects humans through highly infectious arthroconidia, causing substantial morbidity including life-threatening disseminated infections. Due to the low infectious dose, laboratory personnel might become infected during diagnostic procedures. Accordingly, coccidioidomycosis is reported as the most frequent laboratory-acquired systemic mycosis worldwide. This risk is aggravated in non-endemic countries, where the diagnosis may not be suspected. We report on an inadvertent exposure of 44 persons to Coccidioides posadasii in a clinical microbiology laboratory in Chile, the measures of containment after rapid diagnosis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and the lessons learnt in a non-endemic setting.

2502. Host Susceptibility to Andes Hantavirus Infection Associates to a Single Nucleotide Polymorphism at the αVβ3 Integrin

Background

Methods

Results

Conclusion

Disclosures

2059. Comparative Evaluation of Ceftaroline Susceptibility Methods in Clinical Isolates of Methicillin-Resistant Staphylococcus aureus (MRSA): Results from a Multicenter Study

Background

Ceftaroline (CPT) is a last generation cephalosporin with activity against MRSA. Recent data raised concerns regarding routine susceptibility testing in clinical laboratories, suggesting a poor performance for detecting nonsusceptible S. aureus (MIC >1 µg/dL) using either disc or gradient strips (Cantón R 2017)

Aim

To evaluate the results of CPT susceptibility testing with Etest^® and disk diffusion (Kirby–Bauer technique [KB]) as compared with broth microdilution (BMD), in clinical isolates of MRSA obtained from different hospitals in Santiago, Chile.

Methods

During 2017, we prospectively collected consecutive clinical strains of MRSA recovered from the blood or other sterile sites in ten tertiary-care hospitals in Santiago, Chile. One isolate per patient was obtained. Identification was confirmed by MALDI-TOF and susceptibility testing of all isolates was performed at a central lab. CPT susceptibility was evaluated by BMD and KB following CLSI 2017 directions. Etest was performed as per manufacturer’s instructions. Categorical agreement (CA), essential agreement (EA) and very major errors (VME) were evaluated. Susceptibilities were analyzed using CLSI established breakpoints

Results

Forty unique MRSA isolates were tested. Using BMD, the MIC₅₀/MIC₉₀ was 2/4 μg/dL, respectively. Moreover, only 18 (45%) isolates were CPT susceptible. Out of the remaining 22 MRSA strains, 8 (20%) were intermediate and 14 (35%) CPT-resistant (CPT-R). Using Etest, the MIC₅₀/MIC₉₀ was 1/2 μg/dL, with 31 (78%) isolates being considered susceptible and the remaining catalogued as intermediate. CPT susceptibility using KB catalogued 38 (95%) isolates as susceptible and only 2 as intermediate. No CPT-R strains were found by Etest or KB. The CA was for Etest and KB, respectively; Etest’s EA was 80%. Worryingly, out of 14 CPT-R isolates by BMD, 6 were deemed susceptible by Etest and 12 by KB, obtaining VME rates of 43 and 87%, respectively

Conclusion

Performance of both Etest and KB to assess CPT susceptibility in MRSA isolates from Chile was poor, with a unacceptably high proportion of VME, and a CA lower than 50% for both techniques. Correlation of CPT susceptibility with the molecular epidemiology of the isolates is currently being performed

Disclosures

All authors: No reported disclosures.

2560. Multispecies Outbreak of KPC-2 Producing Enterobacteriaceae in a Chilean Pediatric Hospital

Background

Carbapenem-resistant Enterobacteriaceae (CRE) are a critical global health problem. We detected a surge of CRE cases in a pediatric hospital in Chile, a country with a low endemicity of KPC-producing organisms. Herein, we describe the molecular epidemiology of this outbreak.

Methods

CRE isolates from clinical specimens and surveillance rectal swabs (obtained using chromID CARBA SMART agar, BioMerieux) of pediatric patients were collected from July 2015 to January 2017. Species identity was confirmed by MALDI-TOF. Carbapenemase genes (bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48-like) were detected by multiplex PCR, followed by amplification and sequencing of the bla_KPC allele. Conjugation experiments were conducted with representative species as donors and sodium azide-resistant E. coli J53 as recipient. PCR-based plasmid typing (PBRT Diatheva kit) was then performed on donors and recipients. For K. pneumoniae, genetic relatedness was investigated by PFGE, multilocus sequence typing and wzi typing.

Results

Sixty-one CRE clinical and surveillance isolates were obtained from 49 patients aged 17 days to 16 years. bla_KPC-2 was present in 57/62 isolates; no other carbapenemases were found. For 11 patients, multiple cultures were obtained; 4/11 had more than one KPC-harboring species. KPC-harboring isolates displayed ertapenem MICs ranging from 1 to >8 mg/L. Preliminary analyses suggest that bla_KPC-2 is contained within a nonclassical Tn4401 structure (lacking the upstream promoter). Mating experiments indicate that bla_KPC-2 is carried by a conjugative IncN backbone plasmid. Interestingly, K. pneumoniae isolates were nonclonal by PFGE and belonged to multiple STs unrelated to CG258 (ST34, ST36, among others) and different wzi types (37, 154, among others).

Conclusion

We report a multispecies outbreak of KPC-2 producing CRE in children mainly driven by horizontal dissemination of a promiscuous IncN plasmid. The nonclonal, multispecies nature of this outbreak provides insights into the complex dynamics of KPC dissemination in countries like Chile, where the clonal spread of highly successful clones like CG258 is not the predominant dissemination vehicle, and instead HGT-related spread could be playing a more important role.

Disclosures

All authors: No reported disclosures.

Knowledge, attitudes, and practices regarding hantavirus disease and acceptance of a vaccine trial in rural communities of southern Chile

Andes hantavirus cardiopulmonary syndrome, transmitted by Oligoryzomys longicaudatus, has no approved treatment, a case fatality rate of 35%, and documented person-to-person transmission. An Andes vaccine, highly needed for prevention, is in development. We aimed to evaluate knowledge, attitudes and practices (KAP) regarding hantavirus disease and willingness to participate in a future Andes vaccine trials through a cross sectional face-to-face oral survey of a randomly selected adult sample from 2 rural communes in southern Chile. Human subjects approval was obtained from our institutional IRBs, and participants signed informed consent. We enrolled 319 subjects from Corral and 321 from Curarrehue; 98% had heard about hantavirus disease and its reservoir but only half knew about transmission, symptoms and prevention. Participants fear the disease but are only partially aware of their own risk. One third of participants reported presence of rodents inside their homes. Despite moderate confidence in their health system, most subjects perceived vaccines as beneficial, and 93% would accept an approved hantavirus vaccine. Half would agree to participate in a vaccine trial and 29% would allow their children to participate. Motivations to participate were mainly altruistic, while risk perception was the main reason for declining. Knowledge about hantavirus disease and prevention practices require reinforcement, and a vaccine trial seems feasible in these populations.

Molecular method for the detection of Andes hantavirus infection: validation for clinical diagnostics

Hantavirus cardiopulmonary syndrome is a severe disease caused by exposure to New World hantaviruses. Early diagnosis is difficult due to the lack of specific initial symptoms. Antihantavirus antibodies are usually negative until late in the febrile prodrome or the beginning of cardiopulmonary phase, while Andes hantavirus (ANDV) RNA genome can be detected before symptoms onset. We analyzed the effectiveness of quantitative reverse transcription polymerase chain reaction (RT-qPCR) as a diagnostic tool detecting ANDV-Sout genome in peripheral blood cells from 78 confirmed hantavirus patients and 166 negative controls. Our results indicate that RT-qPCR had a low detection limit (~10 copies), with a specificity of 100% and a sensitivity of 94.9%. This suggests the potential for establishing RT-qPCR as the assay of choice for early diagnosis, promoting early effective care of patients, and improving other important aspects of ANDV infection management, such as compliance of biosafety recommendations for health personnel in order to avoid nosocomial transmission.

Person-to-person household and nosocomial transmission of andes hantavirus, Southern Chile, 2011

Four persons became ill after exposure to a patient infected with the virus; 2 cases involved hospital transmission.

Andes hantavirus (ANDV) causes hantavirus cardiopulmonary syndrome in Chile and is the only hantavirus for which person-to-person transmission has been proven. We describe an outbreak of 5 human cases of ANDV infection in which symptoms developed in 2 household contacts and 2 health care workers after exposure to the index case-patient. Results of an epidemiologic investigation and sequence analysis of the virus isolates support person-to-person transmission of ANDV for the 4 secondary case-patients, including nosocomial transmission for the 2 health care workers. Health care personnel who have direct contact with ANDV case-patients or their body fluids should take precautions to prevent transmission of the virus. In addition, because the incubation period of ANDV after environmental exposure is longer than that for person-to-person exposure, all persons exposed to a confirmed ANDV case-patient or with possible environmental exposure to the virus should be monitored for 42 days for clinical symptoms.

Hantavirus pulmonary syndrome, Southern Chile, 1995-2012

Hantavirus is endemic to the Region de Los Lagos in southern Chile; its incidence is 8.5 times higher in the communes of the Andean area than in the rest of the region. We analyzed the epidemiologic aspects of the 103 cases diagnosed by serology and the clinical aspects of 80 hospitalized patients during 1995-2012. Cases in this region clearly predominated during winter, whereas in the rest of the country, they occur mostly during summer. Mild, moderate, and severe disease was observed, and the case-fatality rate was 32%. Shock caused death in 75% of those cases; high respiratory frequency and elevated creatinine plasma level were independent factors associated with death. Early clinical suspicion, especially in rural areas, should prompt urgent transfer to a hospital with an intensive care unit and might help decrease the high case-fatality rate.

High-dose intravenous methylprednisolone for hantavirus cardiopulmonary syndrome in Chile: a double-blind, randomized controlled clinical trial

BACKGROUND

Andes virus (ANDV)-related hantavirus cardiopulmonary syndrome (HCPS) has a 35% case fatality rate in Chile and no specific treatment. In an immunomodulatory approach, we evaluated the efficacy of intravenous methylprednisolone for HCPS treatment, through a parallel-group, placebo-controlled clinical trial.

METHODS

Patients aged >2 years, with confirmed or suspected HCPS in cardiopulmonary stage, admitted to any of 13 study sites in Chile, were randomized by study center in blocks of 4 with a 1:1 allocation and assigned through sequentially numbered envelopes to receive placebo or methylprednisolone 16 mg/kg/day (≤1000 mg) for 3 days. All personnel remained blinded except the local pharmacist. Infection was confirmed by immunoglobulin M antibodies or ANDV RNA in blood. The composite primary endpoint was death, partial pressure of arterial oxygen/fraction of inspired oxygen ratio ≤55, cardiac index ≤2.2, or ventricular tachycardia or fibrillation within 28 days. Safety endpoints included the number of serious adverse events (SAEs) and quantification of viral RNA in blood. Analysis was by intention to treat.

RESULTS

Infection was confirmed in 60 of 66 (91%) enrollees. Fifteen of 30 placebo-treated patients and 11 of 30 methylprednisolone-treated patients progressed to the primary endpoint (P = .43). We observed no significant difference in mortality between treatment groups (P = .41). There was a trend toward more severe disease in placebo recipients at entry. More subjects in the placebo group experienced SAEs (P = .02). There were no SAEs clearly related to methylprednisolone administration, and methylprednisolone did not increase viral load.

CONCLUSIONS

Although methylprednisolone appears to be safe, it did not provide significant clinical benefit to patients. Our results do not support the use of methylprednisolone for HCPS.

CLINICAL TRIALS REGISTRATION

NCT00128180.

APOE and Alzheimer disease: a major gene with semi-dominant inheritance

Apolipoprotein E (APOE) dependent lifetime risks (LTRs) for Alzheimer Disease (AD) are currently not accurately known and odds ratios alone are insufficient to assess these risks. We calculated AD LTR in 7351 cases and 10 132 controls from Caucasian ancestry using Rochester (USA) incidence data. At the age of 85 the LTR of AD without reference to APOE genotype was 11% in males and 14% in females. At the same age, this risk ranged from 51% for APOE44 male carriers to 60% for APOE44 female carriers, and from 23% for APOE34 male carriers to 30% for APOE34 female carriers, consistent with semi-dominant inheritance of a moderately penetrant gene. Using PAQUID (France) incidence data, estimates were globally similar except that at age 85 the LTRs reached 68 and 35% for APOE 44 and APOE 34 female carriers, respectively. These risks are more similar to those of major genes in Mendelian diseases, such as BRCA1 in breast cancer, than those of low-risk common alleles identified by recent GWAS in complex diseases. In addition, stratification of our data by age groups clearly demonstrates that APOE4 is a risk factor not only for late-onset but for early-onset AD as well. Together, these results urge a reappraisal of the impact of APOE in Alzheimer disease.

Highly differentiated, resting gn-specific memory CD8+ T cells persist years after infection by andes hantavirus

In man, infection with South American Andes virus (ANDV) causes hantavirus cardiopulmonary syndrome (HCPS). HCPS due to ANDV is endemic in Southern Chile and much of Argentina and increasing numbers of cases are reported all over South America. A case-fatality rate of about 36% together with the absence of successful antiviral therapies urge the development of a vaccine. Although T-cell responses were shown to be critically involved in immunity to hantaviruses in mouse models, no data are available on the magnitude, specificity and longevity of ANDV-specific memory T-cell responses in patients. Using sets of overlapping peptides in IFN-γ ELISPOT assays, we herein show in 78 Chilean convalescent patients that Gn-derived epitopes were immunodominant as compared to those from the N- and Gc-proteins. Furthermore, while the relative contribution of the N-specific response significantly declined over time, Gn-specific responses remained readily detectable ex vivo up to 13 years after the acute infection. Tetramer analysis further showed that up to 16.8% of all circulating CD3⁺CD8⁺ T cells were specific for the single HLA-B*3501-restricted epitope Gn_465–473 years after the acute infection. Remarkably, Gn_465–473–specific cells readily secreted IFN-γ, granzyme B and TNF-α but not IL-2 upon stimulation and showed a ‘revertant’ CD45RA⁺CD27⁻CD28⁻CCR7⁻CD127⁻ effector memory phenotype, thereby resembling a phenotype seen in other latent virus infections. Most intriguingly, titers of neutralizing antibodies increased over time in 10/17 individuals months to years after the acute infection and independently of whether they were residents of endemic areas or not. Thus, our data suggest intrinsic, latent antigenic stimulation of Gn-specific T-cells. However, it remains a major task for future studies to proof this hypothesis by determination of viral antigen in convalescent patients. Furthermore, it remains to be seen whether Gn-specific T cells are critical for viral control and protective immunity. If so, Gn-derived immunodominant epitopes could be of high value for future ANDV vaccines.

In man, hantavirus cardiopulmonary syndrome (HCPS) caused by Andes Virus (ANDV) is endemic in the Southern cone of Chile and Argentina but cases of HCPS are being increasingly reported all over South America since 1995. HCPS is characterized by fulminant pulmonary edema which progresses to shock and death in about 36% of patients with HCPS. Nevertheless, to date, neither antiviral treatments nor vaccines inducing neutralizing antibodies (NAb) have proven effective against HCPS-causing hantaviruses. We set out for the first study on human cellular immunity towards ANDV in 78 convalescent survivors of ANDV infection. We found that Gn-specific responses were predominant as compared to N- and Gc-specific responses, even up to 13 years after the infection. Surprisingly, most of the Gn-specific responses were restricted to two neighboring epitopes within the Gn carboxyterminus. Interestingly, among HLA-B*3501⁺ patients, Gn_465−473-specific CD8⁺ T-cells showed highly differentiated but resting phenotype and functions. It remains to be seen in future studies whether the immunodominace of Gn-specific T-cells is crucial for protective immunity. Most intriguingly, titers of neutralizing antibodies increased in 10/17 individuals months to years after the acute infection and independently of whether they were residents of endemic areas or not. Thus, our data suggest viral persistence or latency in part of ANDV-convalescent patients. However, it remains a major task for future studies to proof the concept of latent/persistent human ANDV infection by the determination of viral antigen in convalescent patients.

Case report: T-cell responses during clearance of Andes virus from blood cells 2 months after severe hantavirus cardiopulmonary syndrome

Hantavirus Cardiopulmonary Syndrome (HCPS) due to Andes virus (ANDV) is endemic in Chile and Argentina and currently demonstrates a case-fatality rate of 37% in humans. By contrast to the chronically infected rodents, it is believed that ANDV in humans is cleared during the acute phase. Moreover, to date, both magnitude and quality of human T-cell responses during ANDV infection and clearance are unknown. Using IFN-gamma and granzyme B ELISPOT assays as well as flow cytometry, we prospectively studied the ANDV-specific T-cell responses in a 56-year-old convalescing survivor of severe HCPS, whose blood cells remained PCR-positive for ANDV-RNA until day 53 after hospital admission, that is, 67 days after infection and 42 days after discharge. PCR-negativity was closely related to the increase and function of (Gn(46-60))-specific IFN-gamma(+) granzyme B(+) CD8(+) T-cells, but not to neutralizing antibody titers. Concurrently, the phenotype of CD45RA(+)CCR7(-) Gn(46-60)-specific T-cells shifted from a CD28(-)CD27(+) "intermediate" to a CD28(-) CD27(-) "late" effector memory beyond day 53 after hospital admission. This is the first report that shows that ANDV can persist in the human hosts for more than 2 months. Moreover, the kinetics of T-cell responses during ANDV clearance may indicate a major role of T-cells for clearance of ANDV and human immunity to this pathogen.

Incubation period of hantavirus cardiopulmonary syndrome

The potential incubation period from exposure to onset of symptoms was 7–39 days (median 18 days) in 20 patients with a defined period of exposure to Andes virus in a high-risk area. This period was 14–32 days (median 18 days) in 11 patients with exposure for <48 hours.

Neutralizing antibodies in survivors of Sin Nombre and Andes hantavirus infection

We evaluated titers of homotypic and heterotypic neutralizing antibodies (NAbs) to Andes and Sin Nombre hantaviruses in plasma samples from 20 patients from Chile and the United States. All but 1 patient had high titers of NAb. None of the plasma samples showed high titers against the heterologous virus.

378 EFFECT OF TRANSGENE CONCENTRATION AND FLANKING MATRIX ATTACHMENT REGIONS ON THE EFFICIENCY OF ICSI-MEDIATED TRANSGENIC MOUSE PRODUCTION

The efficiency of ICSI-mediated transgenesis can be influenced by many different factors. In this study, we have assessed the impact of transgene concentration and of the presence of transgene-flanking matrix attachment regions (MARs) on the efficiency of this procedure. Presented data include assays with three DNA constructs; a plasmid EGFP of 5.4 kb (pEGFP, Clontech Laboratories, Inc., Palo Alto, CA, USA); this plasmid EGFP construct flanked with two MAR elements (M-EGFP-M; 2.3 kb of the human �-interferon domain boundaries) (Guti�rrez-Ad�n et al. 2000 Transgenic Res. 9, 81-89); and a yeast artificial chromosome (YAC) of 520 kb. ICSI-mediated transgenesis was done in the B6D2 hybrid mouse strain as previously described (Moreira et al. 2004 Biol. Reprod. 71, 1943-1947), using two concentrations (1 and 15 ng/�L) of the M-EGFP-M transgene, three concentrations (1, 6, and 15 ng/�L) of the pEGFP transgene, and three concentrations (2, 3.6, and 5 ng/�L) of the YAC construct. Embryos were cultured in vitro until the 2-cell stage and transferred into Day 1 pseudopregnant females. Live offspring or Day 14 fetuses were analyzed by PCR for the detection of the genomic presence of the integrated transgene. The proportion of transgenics (PT) obtained with 2, 3.6, and 5 ng/�L of the YAC construct was 10, 21, and 13% respectively. A Z-test analysis of the data generated with this construct indicated that the number of transgenic offspring, when expressed as a proportion of injected ova (efficiency rate of the procedure, ER), increased with DNA concentration up to a threshold of 3.6 ng/�L, and suggested that higher concentrations of this transgene (and maybe of co-purifying contaminants) decreased the ER of the procedure. Interestingly, although much higher transgene concentrations were used for the pEGFP construct, this threshold was not reached. With an increase in transgene concentration (from 1 to 15 ng/�L), the PT increased (from 39 to 70%), as well as the ER of the procedure (from 3 to 7%). In addition, independently of the transgene concentration tested, when M-EGFP-M was used, the ER of the procedure and the PT observed were similar to the ones obtained with pEGFP. These results indicate that, regardless of the importance of other factors such as transgene size, purity, and copy number, the concentration to be used on ICSI-mediated transgenesis should be optimized for each construct, in order to maximize the PT among the liveborn offspring and the overall efficiency of the procedure. Our results also indicate that transgene-flanking MARs do not have a significant impact on the efficiency of this transgenesis method.

APOE genotype in cerebrovascular disease and vascular dementia

BACKGROUND

The fact that the allele epsilon 4 of the Apolipoprotein E (APOE) gene could act like a risk factor not only in late-onset familial and sporadic Alzheimer's disease (AD) but also in cerebrovascular disease (CVD) and vascular dementia (VaD) is still controversial.

METHODS

In order to study if epsilon 4 allele is overrepresented not only in AD but also in CVD and VaD, APOE genotyping was undertaken in a series of 247 patients: 26 cases with VaD, 41 cases with CVD but without cognitive impairment (CVD-C), 83 cases with AD and 97 aged-matched "healthy controls" (HC).

RESULTS

Percentages of subjects bearing one or two copies of the epsilon 4 allele was much higher in AD patients (54%) than in either CVD-C (29%) (p<0.05), VaD (15%) (p<0.001) or HC (13%) (p<0.001).

CONCLUSIONS

These results strengthen the hypothesis that involves the APOE epsilon 4 allele as a predisposing factor for AD, but not for CVD or VaD.

Contribution of APOE promoter polymorphisms to Alzheimer's disease risk

OBJECTIVE

To determine whether the effects of APOE promoter polymorphisms on AD are independent of the APOE-epsilon4 allele.

BACKGROUND

Recently, the -491 A-->T and -219 G-->T polymorphisms located in the APOE promoter have been suggested to be risk factors for AD. However, the effects of these polymorphisms have not always been reproduced in case-control studies, possibly because of the strong linkage disequilibrium existing at this locus or the characteristics of the populations studied.

METHODS

Data collection was performed from six independent samples (1,732 patients with AD and 1,926 control subjects) genotyped for APOE exon 4 and the two APOE promoter polymorphisms. The risks associated with the APOE polymorphisms for developing AD were estimated using logistic regression procedures and calculation of odds ratios with 95% CI adjusted by age, sex, and collection center. Independence of the APOE promoter polymorphisms was tested by stratification for APOE-epsilon4 and tertile design was used for age stratification.

RESULTS

The independence of the -491 AA genotype was observed in the whole sample whereas the independence of the -219 TT genotype was observed only in the oldest population.

CONCLUSION

The -491 and -219 APOE promoter polymorphisms incur risk for AD in addition to risk associated with the APOE-epsilon4 allele, with age accentuating the effect of the -219 TT genotype. Because these polymorphisms appear to influence apoE levels, these results suggest that APOE expression is an important determinant of AD pathogenesis.

[Immunogenicity and reactogenicity of a reduced antigen content diphtheria, tetanus and acellular pertussis vaccine dTpa) in 10 to 11 years old children and in adults]

BACKGROUND

New vaccination strategies are needed to control the increasing problem of pertussis in teenagers and adults.

AIM

To determine the immunogenicity and reactogenicity of a diphtheria-tetanus-acellular pertussis (dTpa) vaccine with reduced antigen content.

MATERIAL AND METHODS

A single dose of the dTpa vaccine was administered to 60 children 10 to 11 years old and 60 healthy adults. At the moment of vaccination and one month later, antibody levels were measured against 3 B pertussis antigens: anti-pertussis toxin (PT), anti-pertactin (PRN) and anti-filamentous hemagglutinin (FHA), as well as anti-tetanus and anti-diphtheria antibodies. Local and general symptoms were registered during 14 days following vaccine administration.

RESULTS

Antibody response for PT, FHA and PRN was 98.3%, 100% and 100% in adults and 98.2%, 100% and 98.2% in children. Seropositivity for all pertussis antigens was 100% in adults and in children one month after vaccination. Geometric mean titers (GMT) significantly increased in adults and children. The seroprotection level achieved for tetanus and diphtheria antibodies one month after vaccination was 96.7% for adults and 100% for children, respectively. No serious adverse events were reported during the study. Among local symptoms pain was the most frequent (88-90%), but it was mostly mild or moderate. Solicited general symptoms observed for children and adults, respectively, included headache (37% and 53%), fatigue (18% and 35%) gastrointestinal symptoms (18% and 25%) and fever (8% and 3%). Only one vaccinee had fever above 39 degrees C.

CONCLUSIONS

The dTpa vaccine showed an adequate safety profile and induced an intense immunological response to all antigens in adults and children aged 10-11.

Interaction of alpha-2-macroglobulin and HSV-1 during infection of neuronal cells

We describe the effect of pretreatment with alpha-2-macroglobulin (A2M) on the susceptibility of the human neuroblastoma SKNMC cell line to infection by herpes virus type 1 (HSV-1). ELISA and co-immunoprecipitation experiments confirmed the A2M-HSV-1 interaction in vitro. Indirect immunofluorescence shows that A2M exacerbated the cytopathic effect induced after HSV-1 infection. However, A2M-pretreated SKNMC cells notably produced fewer HSV-1 particles than did the untreated cells, suggesting that A2M could induce a restrictive infection. Furthermore, high levels of HSV-1 and A2M induced the production of nitric oxide (NO) in SKNMC. Preliminary results suggest that A2M might induce apoptosis in HSV-1-infected cells. These findings affirm the conclusion that A2M may interact directly with HSV-1 and modulate the course of the infection in SKNMC human neuroblastoma cells.

Identification of amino acid residues of transcription factor AP-2 involved in DNA binding

AP-2 is a cell-type specific, developmentally regulated transcription factor which has been described as a critical regulator of gene expression during vertebrate development and embryogenesis. Although the overall domains of this factor necessary for their activity have been identified, the exact identity of AP-2 amino acid residues responsible for its interaction with the DNA structure has not yet been described. Here, we describe the identification of a region of AP-2 which was protected by an oligonucleotide probe containing its binding site from trypsin digestion, monitored by peptide mapping by MALDI-TOF mass spectrometry. Furthermore, we analyzed the relative in vitro DNA-binding activity, the stimulatory potency on the AP-2-dependent APOE promoter, as well as the ability to inhibit the effect of the wild-type protein of each one of a set of single-site substitution AP-2 mutants spanning the identified region. Taken together, our data clearly demonstrate that the region between amino acid residues 252-260 of AP-2 is essential for its DNA-binding activity. Particularly, the individual substitution in any of the residues 253, 254, 255, 257 or 260 is sufficient for completely abolishing the interaction with DNA and the stimulation of APOE promoter activity. These results indicate a crucial role of this region in the formation of an active DNA-binding domain and strongly suggest that these residues provide direct contacts with the DNA structure at the AP-2 binding site.

Apolipoprotein E gene promoter polymorphisms in Alzheimer's disease

Alzheimer's disease, the most frequent form of senile dementia, presents in the vast majority of cases as a multifactorial trait, where a series of genetic and environmental risk factors converge. The increasing body of data, both epidemiological and functional, is strengthening the evidence that apolipoprotein E (APOE, gene; apoE, protein) is a true susceptibility factor for the onset of the common form of Alzheimer's disease. The E4 isoform of apoE remains to date as the main genetic risk factor for the disease, although the mechanisms responsible for this association are not well understood. It is also clear that apoE4 is not necessary or sufficient to cause the disease, indicating that other risk and protecting factors exist. ApoE is upregulated in response to nervous system injury, suggesting that it could have a neuroprotective role; on the other hand, there is evidence indicating that apoE is neurotoxic when present at high levels. Thus, apoE levels seem to be relevant for the functionality of the protein. The APOE proximal promoter hosts numerous regulatory elements, raising the possibility that polymorphisms in this region could produce variation in apoE levels by altering APOE transcriptional activity, which could finally result in AD susceptibility. We will review here the current evidence on the relationship between APOE proximal promoter polymorphisms, APOE gene transcriptional activity and apoE protein levels, and risk for AD.

Alzheimer's risk associated with human apolipoprotein E, alpha-2 macroglobulin and lipoprotein receptor related protein polymorphisms: absence of genetic interactions, and modulation by gender

Apolipoprotein E (apoE), the lipoprotein receptor related protein (LRP) and alpha-2 macroglobulin (alpha2M) have been proposed as a functional complex involved in amyloid clearance, a crucial event for Alzheimer's disease development. In this work, we present an epidemiological approach aimed to study the interactions among these genes, age and gender. This approach did not reveal significant associations between the genes; however, the present study indicated that the risk associated with APOE promoter and LRP gene polymorphisms is modulated by gender.

A polymorphism in the tau gene associated with risk for Alzheimer's disease

Searching for tau genetic variations which could be associated with risk for Alzheimer's disease (AD), we have performed a mutational analysis of a region containing the whole exon 11 of the tau gene, which encodes a microtubule binding region critical for tau self-assembly, and we have found a biallelic polymorphism at position +34 of intron 11 (IVS11 + 34G/A). We have analyzed the allelic frequencies of this polymorphism in a case-control sample (167 clinically diagnosed AD and 194 controls) and found that the presence of any G allele (genotypes AG + GG) is associated with a five-fold AD risk in individuals carrying the apolipoprotein E4 allele, strongly suggesting that the combined effect of tau and apoE is relevant in relation with AD pathogenesis.

[Emergence of resistance to macrolides in Streptococcus pyogenes]

BACKGROUND

Diseases produced by Streptoccocus pyogenes are still a problem in Chile, as in the rest of the world. It exhibits in vitro susceptibility to different antimicrobials, but penicillin continues to be the treatment of choice. Alternative drugs have been developed for allergic patients, such as erythromycin, new macrolides and cephalosporins. Nevertheless, resistant strains are appearing due to the indiscriminate use of macrolides.

AIM

To assess present antimicrobial susceptibility of S Pyogenes strains isolated from chilean patients.

MATERIAL AND METHODS

The susceptibility to penicillin, macrolides, clindamycin, cephalotin and vancomycin of 153 S Pyogenes strains, obtained from different health centers of the Metropolitan Region and isolated between 1996 and 1998, was assessed using the Kirby-Bauer method. Agar dilution minimal inhibitory concentration was then determined to macrolide resistant strains.

RESULTS

All strains were susceptible to penicillin. There was a 7.2% cross-resistance to macrolides.

CONCLUSIONS

These results confirm that S Pyogenes resistance to macrolides has increased considerably in the Metropolitan Region of Chile during the last years.

DGGE method for the mutational analysis of the coding and proximal promoter regions of the Alzheimer's disease presenilin-1 gene: two novel mutations

Many different mutations that cause Alzheimer's disease (AD) have been found in the presenilin-1 gene (PSEN1) and are associated with the most aggressive forms of the disease. With the aim of screening for PSEN1 genetic variations, we developed a method based on denaturing gradient gel electrophoresis (DGGE) that allows the mutational analysis of all the coding exons and the proximal promoter of PSEN1 using only four DGGE gels. The analysis by this methodology of a sample of 58 early-onset AD (EOAD) patients nonselected for family history resulted in finding four genetic variants within the PSEN1 coding region, two of which are novel mutations (M233L and A409T), whereas the other two have been reported previously (L282R and E318G). We also found a novel mutation within the PSEN1 proximal promoter (-280 C-->G) that, interestingly, provokes significant changes in the transcriptional activity of the gene in cell lines of neuronal and astrocytic, but not hepatic origin. These data strongly suggest that the region around -280 of PSEN1 promoter contains a regulatory element that controls its transcription specifically in neural cells.

[Antimicrobial resistance of agents causing urinary tract infections in 11 Chilean hospitals. PRONARES project]

BACKGROUND

The computer program WHONET generates a common database to analyze local or general antimicrobial resistance of bacteria. A surveillance of agents causing urinary tract infections in Chile has been performed using this program.

AIM

To report the results after 12 months of urinary tract infection agent surveillance.

MATERIAL AND METHODS

Since November, 1997, a surveillance of in vitro antimicrobial resistance, using agar diffusion techniques, has been performed in 20 to 40 bacterial strains per month, isolated from 11 hospitals in the country. Results have been analyzed using WHONET program.

RESULTS

In first 12 months, 3144 strains, 1625 coming from outpatients, have been studied. Seventy four percent of isolated strains were E coli, 19% were other enterobacteria, 4.1% were non fermenting bacilli and 2.1% were Gram (+) cocci. Sixty five percent of E coli strains were resistant to ampicillin, 11% to cefazolin, 2.5% to cefuroxime, 19% to ceftriaxone, 9% to ceftazidime, 4.2% to gentamicin 1.3% to amikacin, 5.6% to ciprofloxacin, 8.4% to grepafloxacin, 4.3% to nitrofurantoin and 43% to trimeproprim/sulphamethoxazole. Eighty two percent of other enterobacteria strains were resistant to ampicillin, 45.5% to cefazolin, 33.5% to cefuroxime, 26.6% to ceftriaxone, 21.5% to ceftazidime, 30.3% to gentamicin 17.2% to amikacin, 21% to ciprofloxacin, 16.3% to grepafloxacin, 48.2% to nitrofurantoin and 44.6% to trimeproprim/sulphamethoxazole. There were differences in betalactamic resistance among hospitals.

CONCLUSIONS

Noteworthy is the high resistance rates to third generation cephalosporins, evidenced when the new cutoff values for E coli and Klebsiella spp are used. This national surveillance provides updated information on antimicrobial resistance of agents causing urinary tract infections.

Apolipoprotein E promoter and alpha2-macroglobulin polymorphisms are not genetically associated with Chinese late onset Alzheimer's disease

In this study, we investigated two newly reported polymorphisms in association with late onset Alzheimer's disease (AD) in Chinese. They were a -491 A/T polymorphism in the Apolipoprotein E (APOE) promoter region and a five base pair deletion at exon 18 of alpha2-Macroglobin (A2M). There were 196 AD and 180 normal controls (N), which were age- and sex-matched. APOE epsilon4 alleles were significantly increased in AD vs. N (chi2 = 33.3, P < 0.000001). However, neither the -491 A/T (chi2 = 1.13, P = 0.29) nor A2M (chi2 = 0.18, P = 0.67) polymorphism was associated with AD risk, suggesting that these polymorphisms do not represent risk factors for AD in the Chinese population.

Transcription factor AP-2 activity is modulated by protein kinase A-mediated phosphorylation

We recently reported that APOE promoter activity is stimulated by cAMP, this effect being mediated by factor AP-2 [Garcia et al. (1996) J. Neurosci. 16, 7550-7556]. Here, we study whether cAMP-induced phosphorylation modulates the activity of AP-2. Recombinant AP-2 was phosphorylated in vitro by protein kinase A (PKA) at Ser239. Mutation of Ser239 to Ala abolished in vitro phosphorylation of AP-2 by PKA, but not the DNA binding activity of AP-2. Cotransfection studies showed that PKA stimulated the effect of AP-2 on the APOE promoter, but not that of the S239A mutant. Therefore, cAMP may modulate AP-2 activity by PKA-induced phosphorylation of this factor.

The -491 A/T polymorphism in the regulatory region of the apolipoprotein E gene and early-onset Alzheimer's disease

The -491 polymorphism in the promoter region of the apolipoprotein E gene (APOE) has been suggested to be associated with increased risk for Alzheimer's disease (AD) independent of APOE status. We studied the association between the -491 polymorphism and risk for early-onset Alzheimer's disease in 99 Dutch and 78 Spanish patients. In patients with early-onset AD, we found no consistent relationship with a single allele of the -491 polymorphism. Linkage disequilibrium between the polymorphism and the APOE gene was found which most likely might explain the inconsistent findings.

Risk for Alzheimer's disease correlates with transcriptional activity of the APOE gene

While the straightepsilon4 allele of apolipoprotein E ( APOE, gene; ApoE, protein) is widely accepted as a major genetic risk factor for the late onset form of Alzheimer's disease (AD), recent evidence points to variations in ApoE levels as another important factor. We have previously reported that a common variant in the regulatory region of APOE (-491A) is associated with risk for late onset AD. In this report we analyze the association of another APOE promoter polymorphism (-427T/C) with AD in two case-control clinical samples and demonstrate a correlation between APOE promoter transcriptional activity and risk for AD. The association studies show that the allelic variant (-427C) and the haplotype [-491A-427C] of the APOE promoter are associated with increased risk for AD. Study of the transcriptional activity of the common haplotypes defined by combination of the -491 and -427 alleles indicated that the risk for late onset AD positively correlates with transcriptional activity of the APOE gene, suggesting that increases in the local expression of ApoE could be responsible for the association of APOE promoter polymorphism with AD.

Identification of a novel mutation (Leu282Arg) of the human presenilin 1 gene in Alzheimer's disease

Many different mutations, causative of Alzheimer's disease, have been found in the presenilin-1 gene (PS-1). We have developed a screening method based on denaturing gradient gel electrophoresis (DGGE), which allows the mutational analysis of the whole exon 9 of PS-1. Upon the screening of a Spanish sample of early onset familial Alzheimer disease cases, we have found a novel mutation in the PS-1 gene. The mutation (a T to G transition) results in a change of the amino acid at position 282 of the presenilin protein from leucine to arginine. This mutation is located in the hydrophobic domain number 7 (exon 9) close to the site of physiological cleavage processing. The average of onset of the affected members of this family is 43+/-5 years, and the average age of exitus of affected members is 56+/-3 years. The possibility to determine the specific pathologic mechanisms of this mutation is now open.

Allelic polymorphisms in the transcriptional regulatory region of apolipoprotein E gene

In this work, we explored the existence of genetic variants within the apolipoprotein E gene transcriptional regulatory region, using a denaturing gradient gel electrophoresis screening of a region comprising nucleotides -1017 to +406. Upon a population study, three new polymorphic sites (-491, -427 and -219) and two mutations were found. Functional effects of the polymorphisms, assayed by transient transfection and electrophoretic mobility shift assays in a human hepatoma cell line, showed that polymorphisms at sites -491 and -219 of the APOE promoter produce variations in the transcriptional activity of the gene, most probably through differential binding of nuclear proteins.

A polymorphism in the regulatory region of APOE associated with risk for Alzheimer's dementia

The epsilon4 allele of the apolipoprotein E gene (APOE) has been associated with an increased risk of developing Alzheimer's disease (AD; refs 1,2). However, it is apparent that the APOEepsilon4 allele alone is neither necessary nor sufficient to cause the disease. We have recently found three new polymorphisms within the APOE transcriptional regulatory region (M.J.A. et al., manuscript submitted) and now establish an association between one of these polymorphisms (-491A/T) and dementia as observed in Alzheimer's disease, in two independent clinical populations. The results suggest that homozygosity of a common variant (-491A) is associated with increased risk for AD, and that this association is independent of APOEepsilon4 status. In vitro studies suggest that the -491A/T polymorphism may increase risk for AD by altering the level of ApoE protein expression.

Proteolysis of Alzheimer's disease beta-amyloid precursor protein by factor Xa

Amyloid beta-protein is a 4-kDa peptide which originates from proteolysis of a larger protein precursor (APP) and accumulates in senile plaques in brains of Alzheimer's disease (AD) patients. Since secreted APP inhibits factors IXa, Xa and XIa, and thrombin appears to play a role in APP secretion and proteolysis, a relationship between hemostasis system and APP metabolism seems to exist. In this work we investigate the susceptibility to proteolytic cleavage by factor Xa of a fusion construct containing full-length APP prepared in bacteria, and demonstrate that both APP695 and APP770 are substrates for this protease. Factor Xa was found to cleave APP after arginines 102, 268, 510, 573 and 601 (APP695 numeration); most of these sites appear to be common for different coagulation factors. In addition, APP incubation with factor Xa generates an array of six potentially amyloidogenic fragments. Comparative kinetic analysis of APP695 and APP770 cleavage by factor Xa suggests that Kunitz-type inhibitor-containing isoforms exert an inhibitory effect on the protease. However, this inhibition is far from complete even at a 5-fold molar excess of inhibitor. Our results raise the possibility that proteases from the coagulation cascade may contribute to APP proteolysis, and support the notion that these proteases play a role in AD pathogenesis.

Anti-brain spectrin immunoreactivity in Alzheimer's disease: degradation of spectrin in an animal model of cholinergic degeneration

In a previous work, we described the existence of anti-brain spectrin auto antibodies in Alzheimer's disease (AD) patients (J. Neuroimmunol. 68 (1996) 39-44). In this report, we further support our previous observations, showing that sera from 9 out of 18 AD patients, but none of 14 control subjects, immunoreacted with spectrin synthesized by PC12 cells. In addition, degradation of brain spectrin was found to be greatly enhanced in the frontal cortex of rats subjected to an animal model of cholinergic degeneration. Our data suggest that spectrin degradation and generation of anti-spectrin auto antibodies may be related to the cholinergic degeneration encountered in AD.

Apolipoprotein E forms stable complexes with recombinant Alzheimer's disease beta-amyloid precursor protein

Apolipoprotein E (apoE), a protein genetically linked to the incidence of Alzheimer's disease, forms SDS-stable complexes in vitro with beta-amyloid peptide (Abeta), the primary component of senile plaques. In the present study, we investigated whether apoE was able to bind full-length Abeta precursor protein (APP). Using a maltose-binding-protein-APP fusion protein and human very-low-density lipoprotein (VLDL), we detected an interaction of apoE with APP that was inhibited by Abeta or anti-apoE antibody. Saturation-binding experiments indicated a single binding equilibrium with an apparent 1:1 stoichiometry and a dissociation constant of 15 nM. An interaction was also observed using apoE from cerebrospinal fluid or delipidated VLDL, as well as recombinant apoE. APP.apoE complexes were SDS-stable, and their formation was not inhibited by reducing conditions; however, they were dissociated by SDS under reducing conditions. ApoE.APP complexes formed high-molecular-mass aggregates, and competition experiments suggested that amino acids 14-23 of Abeta are responsible for complex-formation. Finally, no differences were found when studying the interaction of APP with apoE3 or apoE4. Taken together, our results demonstrate that apoE may form stable complexes with the Abeta moiety of APP with characteristics similar to those of complexes formed with isolated Abeta, and suggest the intriguing possibility that apoE-APP interactions may be pathologically relevant in vivo.

Molecular epidemiology of human rotaviruses in Santiago, Chile

BACKGROUND

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. Our aim was to characterize the epidemiology of rotavirus antigenic types over time in Santiago, Chile.

METHODS

We prospectively obtained 2097 stool samples for rotavirus testing, VP7 (G1 to G4) and VP4 (P4, P6, P8, P9) typing from children with diarrhea evaluated in emergency rooms of 5 base hospitals of Santiago. In addition 256 rotavirus-positive samples collected between 1985 and 1987 in the north health care area of Santiago were studied.

RESULTS

Of 995 rotavirus-positive samples obtained 825 (82%) were typable for 1 or more VP7 types. G1 represented 81% of the G-typed samples during 1993 through 1995 and 77% during 1985 through 1987, predominating in all health care areas. G2 was next most common in all 5 areas, representing 6 to 23% of typed samples, with 1 area, the Southeast concentrating a significantly higher number of G2 infections. G2 declined from 35% of rotavirus-positive samples in 1993 to 0% in 1995 (P < 0.001), and from 25% to 2% in the north health care area from 1985 to 1987 (P < 0.001). G4 was uncommon and significantly more prevalent in 1985 through 1987 than in 1993 through 1995 (7% vs. 3%, P = 0.015). G3 was not detected. G1P8 (53%) and G2P4 (16%) combinations were by far the most commonly detected G-P associations.

CONCLUSIONS

In Santiago, Chile, rotavirus antigenic type G1P8 has been highly prevalent and G2P4 has circulated in cycles. Differences in epidemiology of rotavirus antigenic types worldwide may prove to be relevant in efficacy of rotavirus vaccines.

Transcription factor AP-2 regulates human apolipoprotein E gene expression in astrocytoma cells

Apolipoprotein E (apoE), one of the major plasma lipoproteins, also is expressed in a variety of cell types, including the glial cells of the nervous system. apoE is involved in processes of degeneration and regeneration after nerve lesions as well as in the pathogenesis of Alzheimer's disease (AD). Glial synthesis of apoE is activated in response to injury both in the peripheral and central nervous system. We now report that the activity of the proximal apoE promoter in astrocytes is upregulated by cAMP and retinoic acid, which act synergistically. Sequence analysis of the apoE promoter indicated the presence of several AP-2 consensus sequences that could mediate the stimulatory effect of cAMP and retinoic acid. The possible functional role of AP-2 was examined by cotransfection of AP-2-deficient HepG2 cells with an apoE promoter construct and a human AP-2 expression construct. Cotransfection with AP-2 significantly elevated apoE promoter activity. DNase I footprinting technique revealed the existence of two binding sites for recombinant AP-2 in regions from -48 to -74 and from -107 to -135 of the apoE promoter. Mutations in these regions markedly impaired the trans-stimulatory effect of AP-2. These results indicate the existence of functional AP-2 sites in the promoter region of apoE that could contribute to the complex regulation of this gene in developmental, degenerative, and regenerative processess of the nervous system.