Prospective validation of the Rockall risk scoring system for upper GI hemorrhage in subgroups of patients with varices and peptic ulcers

OBJECTIVES

The Rockall risk assessment score was devised to allow prediction of the risk of rebleeding and death in patients with upper GI hemorrhage. The score was derived by multivariate analysis in a cohort of patients with upper GI hemorrhage and subsequently validated in a second cohort. Only 4.4% of patients included in the initial study had esophageal varices, and analysis was not performed according to the etiology of the bleeding. Our aim was to assess the validity of the Rockall risk scoring system in predicting rebleeding and mortality in patients with esophageal varices or peptic ulcers.

METHODS

Admissions (n = 358) over 32 months to a single specialist GI bleeding unit were scored prospectively. The distribution of episodes of rebleeding and mortality by Rockall score were statistically analyzed using Fisher's exact test with 99% CIs calculated using a Monte Carlo method. The Child-Pugh score was determined in patients with esophageal varices.

RESULTS

The Rockall score was predictive of both rebleeding and mortality in patients with variceal hemorrhage (both ps < 0.0005), as was the Child-Pugh score (p = 0.001 and p < 0.0005, respectively). The initial Rockall score was predictive of mortality in patients with peptic ulcers (p = 0.01), although the complete score was not (p > 0.05). The complete score did, however, predict rebleeding in these patients (p = 0.001).

CONCLUSION

This is the first study to validate the Rockall score in specific subgroups of patients with esophageal varices or peptic ulcers and suggests that it is particularly applicable to variceal hemorrhage.

Identification and sequence determination of the capsid protein gene of feline calicivirus

We have determined 4380 bases of the sequence from a cDNA clone containing the 3' end of feline calicivirus strain F9. We find four candidate open reading frames of which three are complete and comprise 245, 317 and 2012 nucleotides. The fourth continues toward the 5' end. We have expressed the largest complete open reading frame in E. coli. Sera raised to this antigen react specifically with the capsid protein and its intracellular precursor molecule. N-terminal sequence analysis of purified, mature capsid protein confirms this assignment and has identified the position at which precursor is cleaved.

Acute arthritis of cats associated with feline calicivirus infection

Twelve specific pathogen-free cats were infected either by intra-articular inoculation or by contact exposure to one of two strains of feline calicivirus (FCV), either F65, a field strain originating from an outbreak of lameness in a group of cats, or a vaccine strain. Following either route of exposure, both strains induced signs typical of FCV infection including oral and nasal ulceration, conjunctivitis and ocular discharge. These signs were of equal severity for both virus strains, but overall, following either route of infection, F65 induced more severe disease than the vaccine strain, with marked pyrexia, lethargy and lameness. Vaccine virus only induced a relatively mild lameness following intra-articular inoculation. Gross pathological and histopathological lesions were seen in some of the joints, but again changes were more severe in the F65-exposed cats. Virus was isolated from both normal and affected joints from both groups of F65-exposed cats, and from a joint from each cat inoculated intra-articularly with vaccine virus. Mild transient lameness was also seen in one of two control cats inoculated intra-articularly, but no pathological changes were seen or virus isolated from joints. A cDNA probe used in RNA dot blot hybridisation experiments was found to be specific and more sensitive than virus isolation in detecting FCV in selected tissues. This may be useful in future studies on the pathogenesis of FCV disease and in studies on viral persistence in FCV carriers.

Molecular epidemiology of childhood astrovirus infection in child care centers

This study assessed the role of human astrovirus (HAstV) in outbreaks and sporadic cases of diarrhea among children attending child care centers (CCCs) and determined the infecting astrovirus antigenic types by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequence analysis. Eight astrovirus outbreaks occurred in 6 CCCs. Of 179 children with diarrhea, 36 (20%) had astrovirus-associated diarrhea. Diarrhea stools obtained during diarrhea outbreaks were more likely to contain astrovirus (40/476) than were samples not associated with a diarrhea outbreak (14/452) (P<.001). Type-specific RT-PCR and DNA sequencing identified 5 outbreaks associated with HAstV-1 and 3 outbreaks with HAstV-2. Sequential outbreaks in 2 CCCs occurred with a different type in the same year. Phylogenetic analysis identified 6 clades of HAstV-1 and 2 clades of HAstV-2 during this 1-year surveillance. Astrovirus was a significant cause of diarrhea outbreaks, and 2 antigenic types were present in the community during 1 diarrhea season.

Association of the interleukin 1 receptor antagonist gene with ulcerative colitis in Northern European Caucasians

BACKGROUND AND AIMS

An association between the allele 2 of the interleukin 1 receptor antagonist gene variable number tandem repeats polymorphism in intron 2 and ulcerative colitis was first reported in 1994. Subsequent studies in Caucasian Northern European patients have not confirmed this, although trends towards an association were observed. The lack of statistical significance could reflect inadequate power. In this study the association was reassessed in a large independent set of well characterised Caucasian patients and a meta-analysis of reported patient series was performed.

PATIENTS AND METHODS

A total of 320 patients with endoscopically and histologically confirmed ulcerative colitis (124 pancolitis, 196 left sided and distal disease) and 827 ethnically matched controls were genotyped at polymorphic sites in the interleukin 1 receptor antagonist gene. Carriage rates were compared using chi(2) statistics. A meta-analysis of this and seven previous studies in North European Caucasian patients was performed using the Mantel-Haenszel chi(2) test.

RESULTS

Patients had a significantly increased carriage rate of allele 2 compared with controls (52% v 45%; odds ratio 1.3 (95% confidence interval (CI) 1.01-1.7); p=0.04). The allele 2 carriage rate was highest in extensive colitis (carriage rate 56%; odds ratio 1.5 (95% CI 1.1-2.3) p=0.02) and in individuals who had undergone colectomy (carriage rate 55%; odds ratio 1.5 (95% CI 0.95-2.4); p=0.08). Meta-analysis of all eight studies showed a significant association between carriage of allele 2 and ulcerative colitis (odds ratio 1.23 (95% CI 1.04-1.45); p=0.01).

CONCLUSIONS

The association of the interleukin 1 receptor antagonist gene polymorphism with ulcerative colitis is confirmed. The association is minor and confers only a small risk to an individual but will contribute a high attributable risk in a population due to the high allelic frequency. Accurate phenotypic characterisation defines more homogeneous subsets of patients, such as those with extensive disease, in whom the association is greater.

The isoenzymes of carbonic anhydrase: tissue, subcellular distribution and functional significance, with particular reference to the intestinal tract

1. The total carbonic anhydrase activity in some guinea-pig tissues has been measured using a pH-stat procedure. Stomach, gall bladder, proximal colon and caecum all possess more carbonic anhydrase activity per unit amount of protein than does whole blood.2. The carbonic anhydrase activity of the small intestine is low. Reasons are given for supposing that activity found there is not entirely due to contamination by whole blood, and it is suggested that in this tissue the enzyme may be localized in some cell type other than the columnar absorbing cells.3. Evidence is presented which indicates that heavy metals interfere with the activity of the enzyme as measured in tissue homogenates.4. The distribution and concentration of the two major isoenzymes of carbonic anhydrase have been measured in different tissues. Blood and proximal colon contain both isoenzymes in comparable concentrations, the ratio of the concentration of the ;low activity' isoenzyme to that of the ;high activity' being about 2. The gastric mucosa contains much ;high activity' carbonic anhydrase, but only a negligible amount of the ;low activity' isoenzyme. In the caecal mucosa, the ;low activity' isoenzyme is predominant, the ratio of its concentration to that of the ;high activity' isoenzyme being about 9. It is also found that more than 1.5% of the protein in the caecal mucosa is accounted for as carbonic anhydrase enzymes.5. It is found that some 45% of the total carbonic anhydrase activity of sucrose homogenates of the guinea-pig colon is bound to particles. The activity is located mainly in the nuclear and microvillous fraction and in the ;high-speed supernatant' fraction. The form of enzyme bound is largely of the ;high activity' variety. When the tissue is homogenized in potassium chloride solutions less than 4% of the total activity is recovered in particulate fractions. The amount of activity which is bound to particulate fractions increases as the ionic strength or pH of the homogenate is lowered.6. The findings are discussed in relation to the possible physiological roles of the isoenzymes in tissues other than blood. Possible relationships between the presence of the enzymes and the metabolism and transport of ammonium and fatty acids are considered.

New monoclonal antibodies to oestrogen and progesterone receptors effective for paraffin section immunohistochemistry

Assessment of oestrogen and progesterone receptors (ER and PgR) in breast cancer is widely used for the prediction of response to endocrine therapy and as a prognostic marker. Cytosolic assays have been replaced in many centres by immunochemical techniques, which have many advantages including applicability to small samples, simplicity, and cost-effectiveness. This study describes the generation and characterisation of two novel murine monoclonal antibodies recognizing ER and PgR, designated NCL-ER-6F11 and NCL-PGR respectively, which are effective in heat-treated formalin-fixed, paraffin-embedded tissue. The antibodies have been characterized by Western blotting and by immunohistochemistry on normal and pathological breast and other tissues. NCL-ER-6F11 has been shown to compare favourably with a currently available ER antibody. These antibodies may prove of value in the assessment of hormone receptor status in human breast cancer.

The Antibody-Secreting Cell Response to Infection: Kinetics and Clinical Applications

Despite the availability of advances in molecular diagnostic testing for infectious disease, there is still a need for tools that advance clinical care and public health. Current methods focus on pathogen detection with unprecedented precision, but often lack specificity. In contrast, the host immune response is highly specific for the infecting pathogen. Serological studies are rarely helpful in clinical settings, as they require acute and convalescent antibody testing. However, the B cell response is much more rapid and short-lived, making it an optimal target for determining disease aetiology in patients with infections. The performance of tests that aim to detect circulating antigen-specific antibody-secreting cells (ASCs) has previously been unclear. Test performance is reliant on detecting the presence of ASCs in the peripheral blood. As such, the kinetics of the ASC response to infection, the antigen specificity of the ASC response, and the methods of ASC detection are all critical. In this review, we summarize previous studies that have used techniques to enumerate ASCs during infection. We describe the emergence, peak, and waning of these cells in peripheral blood during infection with a number of bacterial and viral pathogens, as well as malaria infection. We find that the timing of antigen-specific ASC appearance and disappearance is highly conserved across pathogens, with a peak response between day 7 and day 8 of illness and largely absent following day 14 since onset of symptoms. Data show a sensitivity of ~90% and specificity >80% for pathogen detection using ASC-based methods. Overall, the summarised work indicates that ASC-based methods may be very sensitive and highly specific for determining the etiology of infection and have some advantages over current methods. Important areas of research remain, including more accurate definition of the timing of the ASC response to infection, the biological mechanisms underlying variability in its magnitude and the evolution and the B cell receptor in response to immune challenge. Nonetheless, there is potential of the ASC response to infection to be exploited as the basis for novel diagnostic tests to inform clinical care and public health priorities.

Laboratory and molecular surveillance of paediatric typhoidal Salmonella in Nepal: Antimicrobial resistance and implications for vaccine policy

Background

Children are substantially affected by enteric fever in most settings with a high burden of the disease, including Nepal. However pathogen population structure and transmission dynamics are poorly delineated in young children, the proposed target group for immunization programs. Here we present whole genome sequencing and antimicrobial susceptibility data on 198 S. Typhi and 66 S. Paratyphi A isolated from children aged 2 months to 15 years of age during blood culture surveillance at Patan Hospital, Nepal, 2008–2016.

Principal findings

S. Typhi was the dominant agent and comprised several distinct genotypes, dominated by 4.3.1 (H58). The heterogeneity of genotypes in children under five was reduced compared to data from 2005–2006, attributable to ongoing clonal expansion of H58. Most isolates (86%) were non-susceptible to fluoroquinolones, associated mainly with S. Typhi H58 lineage II and S. Paratyphi A harbouring mutations in the quinolone resistance-determining region (QRDR); non-susceptible strains from these groups accounted for 50% and 25% of all isolates. Multi-drug resistance (MDR) was rare (3.5% of S. Typhi, 0 S. Paratyphi A) and restricted to chromosomal insertions of resistance genes in H58 lineage I strains. Temporal analyses revealed a shift in dominance from H58 Lineage I to H58 Lineage II, with the latter being significantly more common after 2010. Comparison to global data sets showed the local S. Typhi and S. Paratyphi A strains had close genetic relatives in other South Asian countries, indicating regional strain circulation. Multiple imports from India of ciprofloxacin-resistant H58 lineage II strains were identified, but these were rare and showed no evidence of clonal replacement of local S. Typhi.

Significance

These data indicate that enteric fever in Nepal continues to be a major public health issue with ongoing inter- and intra-country transmission, and highlights the need for regional coordination of intervention strategies. The absence of a S. Paratyphi A vaccine is cause for concern, given its prevalence as a fluoroquinolone resistant enteric fever agent in this setting.

Defective translation of measles virus matrix protein in a subacute sclerosing panencephalitis cell line

Subacute sclerosing panencephalitis (SSPE) is a slowly progressing fatal human disease of the central nervous system (CNS) that is associated with measles virus persistence. Virus nucleocapsids are present in the brain and the patient is in a state of hyperimmunization towards this agent. However, although all other structural polypeptides are recognized by the immune system, there is a markedly decreased antibody response towards virus matrix or membrane protein. Matrix protein has not been detected in brain cells and infectious virus is not present. The absence of this virus structural polypeptide is thought to account for the apparent restriction in virus maturation both in vivo and in vitro. SSPE viruses can only rarely be rescued from brain tissue by co-cultivation or cell fusion techniques using tissue culture cell lines susceptible to measles virus infection. Often this procedure fails to yield a lytic budding virus but produces instead a carrier cell line in which the agent is cell associated. These lines (known as SSPE cell lines) also do not contain matrix protein. However, the reason for this deficiency is unknown. We have therefore now examined an SSPE cell line which does not yield infectious virus in order to define this process further. We found that although messenger RNA for membrane protein was present, it was unable to form normal matrix protein in translation reactions.

Identification and sequence determination of the capsid protein gene of human astrovirus serotype 1

Abstract We present the sequence of an open reading frame (ORF) at the 3′ end of human astrovirus serotype 1. Primer extension experiments showed that the RNA expressing this gene is shorter than the complete ORF, and could form a protein of M_r 85 540. The protein was expressed by recombinant baculovirus and was recognized by anti‐virion serum, indicating a structural role. Sequence comparison indicates that astrovirus serotypes 1 and 2 differ markedly in the C‐terminal half of the protein but are well conserved towards the N‐terminus.

Cleavage of eukaryotic initiation factor eIF4G and inhibition of host-cell protein synthesis during feline calicivirus infection

Caliciviruses are small, non-enveloped, positive-stranded RNA viruses that are pathogenic for both animals and man. Although their capsid structure and genomic organization are distinct from picornaviruses, they have similarities to these viruses in their non-structural proteins. Picornaviruses induce a rapid inhibition of host-cell cap-dependent protein synthesis and this is mainly achieved through cleavage of eIF4G and/or dephosphorylation of 4E-BP1. In this study, the effect of calicivirus infection was examined on host-cell protein synthesis in order to determine whether they also induce host shut-off. We report that infection of cells with feline calicivirus (FCV) leads to the inhibition of cellular protein synthesis. This is accompanied by the cleavage of the eukaryotic translation initiation factors eIF4GI and eIF4GII in a manner reminiscent of that induced by picornaviruses. However, the cleavages occur at different sites. The potential mechanisms of these cleavage events and the implications for the translation of calicivirus mRNA are discussed.

Lower Risk of Multisystem Inflammatory Syndrome in Children With the Delta and Omicron Variants of Severe Acute Respiratory Syndrome Coronavirus 2

Little is known about the risk of multisystem inflammatory syndrome in children (MIS-C) with different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. In southeast England, MIS-C rates per confirmed SARS-CoV-2 infections in children aged 0-16 years were 56% lower (rate ratio [RR], 0.34 [95% confidence interval {CI}, .23-.50]) during prevaccine Delta, 66% lower (RR, 0.44 [95% CI, .28-.69]) during postvaccine Delta, and 95% lower (RR, 0.05 [95% CI, .02-.10]) during the Omicron period.

Measles virus gene expression in subacute sclerosing panencephalitis

RNA was extracted from the diseased brain of a case of human subacute sclerosing panencephalitis (SSPE) and analysed for the expression of measles-specific RNA. Measles virus-specific mRNAs were present, but the amount of matrix (M) protein mRNA was greatly reduced in comparison to lytically infected cells and phospho- (P) protein mRNA was hardly detectable whereas the level of the corresponding intermediate-sized (is-) RNA was greatly increased. RNA obtained from the human brain was also translated in vitro and measles virus nucleocapsid and P protein was produced. However, in marked contrast to control reactions M protein was not detected in the products formed by translation in vitro. These results indicate an impaired measles virus M protein mRNA synthesis in infected brain tissue.

Antigenic characterization of measles and SSPE virus haemagglutinin by monoclonal antibodies

Hybrid cells secreting monoclonal antibodies directed against the haemagglutinin (H) protein of measles virus (Edmonston) were produced by fusion of mouse myeloma cells with spleen cells derived from immunized mice. Measles antibodies secreted by these cells were tested for their ability to react with measles virus in immunoprecipitation experiments and assays of binding, neutralization, haemagglutination inhibition and haemolysin inhibition. On this basis 21 out of 75 hybridomas could be defined and divided into five functional groups with different properties. However, when tested against other measles virus strains, including those isolated from subacute sclerosing panencephalitis (SSPE) patients, normalized radioimmunoassay (RIA) binding titres showed that the extent to which a given antibody bound could vary greatly with the virus strain examined. Moreover, the biological actions within a group were found to be very heterogeneous, even when high antibody binding titres were observed. These results suggest that different measles virus strains, which are not distinguishable by polyvalent sera, do in fact possess antigenic differences. Furthermore, the functional significance of a given virus epitope may vary from strain to strain. Hybridoma antibodies were also used to demonstrate the occurrence of antigenic changes within the H polypeptide of SSPE virus during the course of non-productive, persistent infection in vitro.

Cell culture adaptation of astrovirus involves a deletion

Astroviruses have been adapted to culture by serial blind passage in primary human embryo cells. All viruses thus adapted possess a 45-nucleotide deletion relative to fecal viruses or isolates made in CaCo-2 cells; this deletion may be responsible for the change in host cell range.

Helicobacter pylori antimicrobial resistance in the United Kingdom: the effect of age, sex and socio-economic status

BACKGROUND

Helicobacter pylori antimicrobial resistance is the most common reason for eradication failure. Small studies have shown metronidazole resistance to be more prevalent in certain population groups.

AIM

To determine the resistance rates in a large cohort of patients from a single centre in the UK, and to evaluate resistance patterns over time, according to age, sex and socio-economic status.

METHODS

Consecutive patients with H. pylori-positive antral gastric biopsy samples were studied from 1994 to 1999. Susceptibility testing was performed to metronidazole, tetracycline, macrolide and amoxicillin by the modified disk diffusion

METHOD

The Jarman under-privileged area score was used as a measure of socio-economic status.

RESULTS

A total of 1064 patients were studied. Overall metronidazole resistance was 40.3%, decreasing with age (P < 0.0001, odds ratio for patients over 60 years 0.63, 95% CI: 0.48-0.80). Women were more likely to have metronidazole resistant strains (P=0.003, odds ratio 1.5, 95% CI: 1.15-1.91), but there was no association with Jarman score. Macrolide resistance was associated with metronidazole resistance (P=0.03, odds ratio 2.14, 95% CI: 1.07-4.28).

CONCLUSIONS

Metronidazole resistance in H. pylori is highly prevalent and more common in women and the young, but does not appear to be related to socio-economic status.

Location of monoclonal antibody binding sites in the capsid protein of feline calicivirus

We report the localization of three monoclonal antibody (MAb) binding sites in the capsid protein of feline calicivirus. Gene fragments were generated by restriction enzyme digestion or the polymerase chain reaction, and expressed as beta-galactosidase fusion proteins in Escherichia coli. These chimeric molecules were screened using three MAbs. A non-neutralizing MAb recognized a region within 36 amino acids of the C terminus. Two neutralizing MAbs bound to a different region of 37 amino acids in the centre of the protein. Comparative sequence analysis shows this area to be the major variable region of the capsid protein.

Metastasis-free survival following treatment for uveal melanoma with either stereotactic radiosurgery or enucleation

PURPOSE

To determine whether metastasis-free survival following stereotactic radiosurgery is comparable with that following enucleation in a cohort of patients with choroidal and ciliary body melanoma.

METHODS

This was a non-randomized, retrospective study of 196 patients with uveal melanoma treated between 1990 and 2000. A total of 118 eyes were enucleated and 78 eyes were treated with stereotactic radiosurgery. The following variables were recorded: age and sex of patient; tumour location, volume and height; the presence of retinal detachment, and extrascleral extension. Tumour location was divided into three categories: within the posterior pole; beyond the limits of the posterior pole but not including the ciliary body, and ciliary body location. Analysis of survival time was performed using Kaplan-Meier estimation of survival curves and Cox's proportional hazards regression modelling.

RESULTS

The 5-year cumulative metastasis-free survival rate was 51% in the enucleation treatment group compared to 74% in the stereotactic treatment group. However, in the multivariate analysis there was no statistical difference in survival rates between the two treatment groups. The only variables that influenced survival rates were tumour location (p = 0.002), ciliary body tumours with the worst prognosis, and tumour volume (p = 0.001).

CONCLUSIONS

Tumour size and location at presentation determined metastasis-free survival. Large ciliary body tumours had the highest risk of metastasis. Metastasis-free survival after stereotactic radiosurgery was comparable to that after enucleation.

Advancing Identity Theory

This study advances identity theory by testing the impact of (moral) identity activation on behavior in different social contexts. At a large southwestern university, 343 undergraduate students completed a survey that measured meanings of their moral identity. Later they completed a laboratory task in which they were awarded more points than they deserved. Participants were given the opportunity to admit (or not admit) the improper point reward. Behavior during the task was examined in varying social contexts: when a participant’s moral identity was activated (or not activated) and when participants completed the task while alone, in a group, or in a group where a numeric majority pressured them to not admit being given extra points. Results show that individuals behave in accord with identity meanings across social contexts when an identity is activated. Implications for identity theory regarding identity activation and how identities influence behavior across social contexts are discussed.

Self-controlled feedback is effective if it is based on the learner's performance: a replication and extension of Chiviacowsky and Wulf (2005)

The learning advantages of self-controlled feedback schedules compared to yoked schedules have been attributed to motivational influences and/or information processing activities with many researchers adopting the motivational perspective in recent years. Chiviacowsky and Wulf (2005) found that feedback decisions made before (Self-Before) or after a trial (Self-After) resulted in similar retention performance, but superior transfer performance resulted when the decision to receive feedback occurred after a trial. They suggested that the superior skill transfer of the Self-After group likely emerged from information processing activities such as error estimation. However, the lack of yoked groups and a measure of error estimation in their experimental design prevents conclusions being made regarding the underlying mechanisms of why self-controlled feedback schedules optimize learning. Here, we revisited Chiviacowsky and Wulf’s (2005) design to investigate the learning benefits of self-controlled feedback schedules. We replicated their Self-Before and Self-After groups, but added a Self-Both group that was able to request feedback before a trial, but could then change or stay with their original choice after the trial. Importantly, yoked groups were included for the three self-controlled groups to address the previously stated methodological limitation and error estimations were included to examine whether self-controlling feedback facilitates a more accurate error detection and correction mechanism. The Self-After and Self-Before groups demonstrated similar accuracy in physical performance and error estimation scores in retention and transfer, and both groups were significantly more accurate than the Self-Before group and their respective Yoked groups (p’s < 0.05). Further, the Self-Before group was not significantly different from their yoked counterparts (p’s > 0.05). We suggest these findings further indicate that informational factors associated with the processing of feedback for the development of one’s error detection and correction mechanism, rather than motivational processes are more critical for why self-controlled feedback schedules optimize motor learning.

Prevalence of human astrovirus serotype 4: capsid protein sequence and comparison with other strains

Astrovirus serotype 4 has increased in relative prevalence in the Oxford, UK area in 1993. The structural gene of human astrovirus serotype 4 has been sequenced and the results indicate that this protein differs substantially from serotypes 1 and 2. In particular, conservation at the C terminus is greatly reduced. However, amino acid substitutions in this region show a strong conservation in character suggesting that structural or functional constraints operate in this region.

Prevalence of antibodies to astrovirus types 1 and 3 in children and adolescents in Norfolk, Virginia

OBJECTIVE

To determine the prevalence of antibody to human astrovirus types 1 (HAstV-1) and 3 (HAstV-3) in children.

METHODS

Sera from children hospitalized in Norfolk, VA, for noninfectious conditions were collected for a 1-month period every 6 months from 1993 to 1996 and tested by enzyme immunoassay for antibody to HAstV-1 and HAstV-3 with the use of baculovirus-expressed recombinant capsid proteins as antigens.

RESULTS

The seroprevalence of 393 infants and children to HAstV-1 decreased from 67% in infants <3 months of age to 7% by 6 to 8 months of age, consistent with loss of transplacental antibodies. Children acquired HAstV-1 antibody with a peak prevalence of 94% at 6 to 9 years of age (P < 0.001). Antibodies to HAstV-3 exhibited a lower prevalence, with 26% positive at <3 months, 0% at 6 to 11 months and 42% by 6 to 9 years of age. HAstV-1 seroprevalence in children O to 2 months of age decreased from 89% in November, 1993, to 40% in November, 1996 (P = 0.009).

CONCLUSIONS

Astrovirus type-specific antibody prevalence can be measured by baculovirus-expressed capsid antigens in an enzyme immunoassay. Children developed antibody to HAstV-1 (94%) and to HAstV-3 (42%) by 6 to 9 years of age indicating frequent exposure to these enteric viruses in infancy and early childhood.