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Biomedical subjects

R I Glass

Publications and source records attributed to R I Glass.

At least 145 records · Page 8Linked to original sources
PubMed1994

Characterization of a human astrovirus serotype 2 structural protein (VP26) that contains an epitope involved in virus neutralization.

An improved purification procedure for human astrovirus serotype 2 (H-Ast2) has facilitated the isolation of a neutralizing monoclonal antibody (PL-2) directed against one of the major structural proteins (VP26) of H-Ast2. A minor component (VP29) of the virus particles is also recognized by PL-2 antibody. Immunofluorescent staining indicated that VP26 (and/or VP29) has mainly a cytoplasmic location in LLCMK2-infected cells. Immunoelectron microscopy demonstrated that the PL-2 epitope was present in the surface of astrovirus particles. Pulse-chase radiolabeling and immunoprecipitation of H-Ast2-infected cell extracts identified a P86 precursor of VP26. Several intermediate protein species (P74 to P35) that shared the PL-2 epitope were also identified in the infected cells. Finally, partial N-terminal sequencing of VP29 and VP26 polypeptides demonstrated that they originated by alternative processing of P86 after residues 361 and 394, respectively. These results corroborate the location of the astrovirus structural genes at the 3' end of the viral genome included in the previously identified 2.8-kb subgenomic RNA.

Amino Acid Sequence↗
PubMed1994

Comparison of the polymerase region of small round structured virus strains previously classified in three antigenic types by solid-phase immune electron microscopy.

We have used a reverse transcription-polymerase chain reaction with nested sets of primers to determine the nucleotide sequences of a 166 base pair segment of the RNA polymerase region of seven strains of small round structured viruses (SRSVs) from the United Kingdom. These SRSV strains were previously classified by solid-phase immune electron microscopy into three antigenic types--UK2, UK3 and UK4, which are comparable to the prototype strains Norwalk virus, Hawaii agent, and Snow Mountain agents, respectively. Based on their sequences, the seven strains from the United Kingdom could be divided into two groups. The first group included two strains of the UK2 type along with Norwalk virus and Southampton virus and the second group included three strains of UK3 and two strains of UK4 types. Viruses in the first group showed 75.3%-77.1% nucleotide and 89.1%-94.6% amino acid identity with Norwalk virus while those of the second group showed 60.8%-63.3% nucleotide and 67.3%-69.1% amino acid identity. Nucleotide and amino acid identity within the second group ranged between 91.6%-99.4% and 96.4%-100%, respectively. These results suggest that the SRSVs antigenically related with Norwalk virus, Hawaii agent, and Snow Mountain agent, can be classified into two genotypes on the basis of their sequences in the RNA polymerase region.

Adult↗
PubMed1994

High prevalence of rotavirus infection among neonates born at hospitals in Delhi, India: predisposition of newborns for infection with unusual rotavirus.

Although rotavirus is the most common cause of diarrhea in children older than 3 months of age, neonatal infections, which are asymptomatic, have rarely been surveyed and have been identified in only a few discrete nosocomial outbreaks. After such a nosocomial outbreak of rotavirus infection among newborns at a hospital in Delhi, we screened infants born at five other nurseries in the immediate area to assess the prevalence of neonatal infections and to determine whether the unique neonatal rotavirus strain, 116E, previously identified in Delhi, was present in other settings. Infection was documented in 43 to 78% of hospitalized infants between 4 and 6 days of life born at five of the six hospitals. Infection with strains related to 116E were the most common, but other unusual strains and no strains common in the community were detected. In addition a shift in genotype was observed among specimens collected from two of these hospitals during a 2-year period. Our observation that neonatal rotavirus infections are more common than recognized previously would encourage the administration of rotavirus vaccines during the newborn period and suggests that the low efficacy of vaccines observed during trials in developing countries may be caused by early natural exposure of infants before immunization. The extraordinary predisposition of neonates for unusual rotavirus strains not commonly found in the community should encourage others to screen neonates for this infection, characterize the strains more fully and attempt to understand at a molecular level the unique relationship between the infecting strain type and the age of the host.

Feces↗
PubMed1994

Norwalk virus-associated gastroenteritis traced to ice consumption aboard a cruise ship in Hawaii: comparison and application of molecular method-based assays.

Investigation of an outbreak of acute nonbacterial gastroenteritis on a cruise ship provided an opportunity to assess new molecular method-based diagnostic methods for Norwalk virus (NV) and the antibody response to NV infection. The outbreak began within 36 h of embarkation and affected 30% of 672 passengers and crew. No single meal, seating, or food item was implicated in the transmission of NV, but a passenger's risk of illness was associated with the amount of ice (but not water) consumed (chi-square for trend, P = 0.009). Of 19 fecal specimens examined, 7 were found to contain 27-nm NV-like particles by electron microscopy and 16 were positive by PCR with very sensitive NV-specific primers, but only 5 were positive by a new highly specific antigen enzyme immunoassay for NV. Ten of 12 serum specimen pairs demonstrated a fourfold or greater rise in antibody titer to recombinant baculovirus-expressed NV antigen. The amplified PCR band shared only 81% nucleotide sequence homology with the reference NV strain, which may explain the lack of utility of the fecal specimen enzyme immunoassay. This report, the first to document the use of these molecular method-based assays for investigation of an outbreak, demonstrates the importance of highly sensitive viral diagnostics such as PCR and serodiagnosis for the epidemiologic investigation of NV gastroenteritis.

Antibodies, Viral↗
PubMed1994

Characterization of a variant strain of Norwalk virus from a food-borne outbreak of gastroenteritis on a cruise ship in Hawaii.

A gastroenteritis outbreak affecting at least 217 (41%) of 527 passengers on a cruise ship was caused by a variant strain of Norwalk virus (NV) that is related to but distinct from the prototype NV strain. Consumption of fresh-cut fruit served at two buffets was significantly associated with illness (P < or = 0.01), and a significant dose-response relationship was evident between illness and the number of various fresh-cut fruit items eaten. Seven (58%) of 12 paired serum specimens from ill persons demonstrated at least fourfold rises in antibody response to recombinant NV capsid antigen. A 32-nm small round-structured virus was visualized by electron microscopy in 4 (29%) of 14 fecal specimens, but none of the 8 specimens that were examined by an enzyme immunoassay for NV antigen demonstrated antigen. Four (40%) of 10 fecal specimens were positive by reverse transcriptase-PCR by using primer pairs selected from the polymerase region of NV. In a 145-bp region, the PCR product shared only 72% nucleotide sequence identity with the reference NV strain and 77% nucleotide sequence identity with Southampton virus but shared 95% nucleotide sequence identity with UK2 virus, a United Kingdom reference virus strain. In addition, the outbreak virus was serotyped as UK2 virus by solid-phase immune electron microscopy. The genetic and antigenic divergence of the outbreak strain from the reference NV strain highlights the need for more broadly reactive diagnostic assays and for improved understanding of the relatedness of the NV group of agents.

Antigenic Variation↗
PubMed1994

Serum antibody response to recombinant major inner capsid protein following human infection with group B rotavirus.

Recombinant major inner capsid protein (VP6) of the IDIR strain of group B rotavirus (GBR) was incorporated in a solid-phase immunoassay to access antibody response to infection in humans. Expression of VP6 in insect cells permitted design of a highly sensitive assay that avoided the contaminants present in GBR antigens obtained from fecal specimens. Among patients infected with the ADRV strain of GBR in China, increased reactivity with recombinant VP6 was observed in convalescent-phase sera in comparison with sera obtained shortly after infection (P = 0.0084). Anti-VP6 antibodies were detectable as soon as 7 days after onset of gastrointestinal symptoms, and serum reactivity persisted in specimens drawn more than 1 year after infection. Solid-phase immunoassay with recombinant VP6 was next employed in order to assess anti-GBR antibody in 513 serum specimens obtained from 423 Maryland residents (ages, 7 months to 96 years; median age, 42 years). Four individuals (< 1%) exhibited serum antibodies directed against the recombinant VP6 (ages, 54 to 95 years; mean age, 77 years). Examination of 129 additional serum specimens including some from other geographic regions of the United States failed to reveal the presence of anti-GBR antibody. Anti-GBR antibody was also not detected in any of 131 serum specimens from 60 staff and residents of a nursing home in Switzerland. While infection of humans with GBR has been uncommon in these locations outside of China, the detection of serum antibodies in older individuals in the United States either indicated an unknown, age-related risk factor or may have indicated infection in the more distant past. The availability of these reagents should allow surveys for GBR infection among additional populations that have not previously been investigated.

Adolescent↗
PubMed1994

Characterization of rotavirus strains from newborns in New Delhi, India.

Between 1986 and 1993, 72% of rotavirus strains isolated from newborns at five hospitals in New Delhi, India, had long electropherotypes, subgroup II VP6 antigens, and G and P genotypes (G9P11) identical to those of prototype strain 116E. A novel strain with a G9P6 genotype, representing 13% of the isolates, was identified. These results demonstrate that G9P11 and G9P6 rotavirus strains are common in nurseries in New Delhi.

Base Sequence↗
PubMed1994

Intrafamilial outbreak of astrovirus gastroenteritis in São Paulo, Brazil.

This report describes an intrafamilial outbreak of astrovirus-associated gastroenteritis that occurred among 5 children in a family living in the State of São Paul, Brazil. Astrovirus was detected by direct electron microscopy (DEM) and confirmed by solid phase immune electron microscopy (SPIEM) using astrovirus reference serum (T2-6-89). The rise in titre of astrovirus antibody in patients' sera was observed by IEM using acute and convalescent-phase sera. Combined use of the EM techniques to detect virus in stool and antibody rise in sera led us to conclude that this intrafamilial outbreak might have been caused by astrovirus infection. In Brazil, astrovirus may be a more common agent of gastroenteritis than in currently appreciated.

Antibodies, Viral↗
PubMed1994

Endemic necrotizing enterocolitis: lack of association with a specific infectious agent.

We conducted a comprehensive analysis of bacterial, parasitic and viral agents present in stool samples of 23 necrotizing enterocolitis cases and 23 matched and 10 random controls. Enterococcus spp., Staphylococcus epidermidis, and Escherichia coli were the most common aerobic bacterial species isolated. Astrovirus was identified in a stool sample from one control. Eight infants were bacteremic; in 7 of 8 the same organism was also present in the stool. No one bacterial species or strain (as identified by plasmid profile analysis) was associated with occurrence of illness. Plasmid analysis further suggested that each infant was colonized with his or her own distinctive aerobic bacterial flora. With the exception of isolates from two control patients which hybridized with a probe for diffuse adherence, no diarrheagenic E. coli was identified. Five (45%) of 11 case infants were colonized with coagulase-negative staphylococci (all S. epidermidis) that produced delta-hemolysin in vitro, as compared with 13 (87%) of 15 control infants. Necrotizing enterocolitis was not associated with an increased ability to ferment carbohydrate, as measured by in vitro beta-galactosidase activity. Our data do not support the hypothesis that endemic necrotizing enterocolitis in our institution is caused by a single infectious agent, nor was there evidence that previously proposed virulence mechanisms such as production of delta-hemolysin or increased in vitro carbohydrate fermentation play a critical role in disease occurrence.

Bacteriological Techniques↗
PubMed1993

RNA sequence of astrovirus: distinctive genomic organization and a putative retrovirus-like ribosomal frameshifting signal that directs the viral replicase synthesis.

The genomic RNA of human astrovirus was sequenced and found to contain 6797 nt organized into three open reading frames (1a, 1b, and 2). A potential ribosomal frameshift site identified in the overlap region of open reading frames 1a and 1b consists of a "shifty" heptanucleotide and an RNA stem-loop structure that closely resemble those at the gag-pro junction of some retroviruses. This translation frame-shift may result in the suppression of in-frame amber termination at the end of open reading frame 1a and the synthesis of a nonstructural, fusion polyprotein that contains the putative protease and RNA-dependent RNA polymerase. Comparative sequence analysis indicated that the protease and polymerase of astrovirus are only distantly related to the respective enzymes of other positive-strand RNA viruses. The astrovirus polyprotein lacks the RNA helicase domain typical of other positive-strand RNA viruses of similar genome size. The genomic organization and expression strategy of astrovirus, with the protease and the polymerase brought together by predicted frameshift, most closely resembled those of plant leuteoviruses. Specific features of the sequence and genomic organization support the classification of astroviruses as an additional family of positive-strand RNA viruses, designated Astroviridae.

Base Sequence↗
PubMed1993

Enteric viruses and diarrhea in HIV-infected patients. Enteric Opportunistic Infections Working Group.

BACKGROUND: Diarrhea occurs frequently among persons with the acquired immunodeficiency syndrome, but the cause often remains unknown. We used a group of diagnostic assays to determine which viruses were etiologic agents of diarrhea in a group of persons infected with the human immunodeficiency virus (HIV). METHODS: Stool and serum specimens were obtained from HIV-infected patients enrolled in a longitudinal study in Atlanta. Fecal specimens from patients with diarrhea and from control patients without diarrhea were screened by electron microscopy, polyacrylamide-gel electrophoresis, and enzyme immunoassays for rotaviruses, enteric adenoviruses, caliciviruses, picobirnaviruses, and astroviruses. Paired serum samples were tested for antibody responses to Norwalk virus and picobirnavirus. RESULTS: Viruses were detected in 35 percent of 109 fecal specimens from patients with diarrhea but in only 12 percent of 113 specimens from those without diarrhea (P < 0.001). Specimens from patients with diarrhea were more likely than those from patients without diarrhea to have astrovirus (12 percent vs. 2 percent, P = 0.003); picobirnavirus (9 percent vs. 2 percent, P = 0.017); caliciviruses, including small round structured viruses (6 percent vs. 1 percent, P = 0.062); and adenoviruses (9 percent vs. 3 percent, P = 0.047). They were also more likely to have a mixed viral infection (6 percent vs. 0 percent, P = 0.006). With the use of polyacrylamide-gel electrophoresis to analyze concentrated RNA extracts from stool, picobirnavirus was detected in fecal specimens from 6 of the 65 patients with diarrhea and was associated with prolonged viral shedding and chronic diarrhea. No rotaviruses, enteric adenoviruses, or instances of seroconversion to positivity for Norwalk virus were observed. CONCLUSIONS: Novel enteric viruses such as astrovirus and picobirnavirus may be more important etiologic agents of diarrhea in HIV-infected patients than previously recognized and may be more common than either bacterial or parasitic enteropathogens.

Adenoviruses, Human↗
PubMed1993

Similarity of the VP4 protein of human rotavirus strain 116E to that of the bovine B223 strain.

Rotavirus strain 116E was isolated from the fecal specimen of a newborn infant from New Delhi who had no symptoms of diarrhea. The strain could not be P typed using the PCR method recently developed in our laboratory so we have sequenced the 4th gene segment that encodes the VP4 protein using viral transcript RNA prepared in vitro. This gene is 2353 base pairs in length and codes for a protein 772 amino acids long which begins with a methionine initiation codon at nucleotides 11 to 13 and ends with a single termination codon at nucleotides 2327 to 2329. Northern blot analysis demonstrates that the VP4 protein of this strain is encoded by genome segment 4. This gene is closely related to the VP4 gene of the bovine B223 strain (P type 11) at both the nucleotide (90.8% identity) and amino acid (92.2% identity) levels, but is unique from those of strains from P types 1 to 10. The close relatedness of the VP4 proteins of strains 116E and B223 is demonstrated by the amino acid composition of the potential trypsin cleavage sites and their flanking sequences, the size of the cleavage fragments, and conservation of most cysteine and proline residues. Comparative amino acid analyses of the variable regions thought to be important in VP4 antigenicity are consistent with the hypothesis that strain 116E may represent the first reported human P type 11 strain.

Amino Acid Sequence↗
PubMed1993

Characterization of the G serotype and genogroup of New Delhi newborn rotavirus strain 116E.

We recently reported that the culture-adapted neonatal rotavirus strain 116E represented the first P type 11 human rotavirus, based on the close relationship of its VP4 protein to that of the bovine serotype G10P11 strain B223. In this study, we demonstrated by sequence analysis and cross-neutralization studies that the VP7 protein of 116E is closely related to those of the human serotype G9 strains, F45 and WI61, but distinct from B223 and other rotaviruses. Low-level cross-neutralization was also observed between strains 116E and B223, probably because of the antigenic similarity of their VP4 proteins. We have demonstrated by RNA-RNA hybridization that strain 116E is a reassortant between strains from the Wa and bovine (KK3-like) genogroups, deriving at least seven genes from the former and at least one gene from the latter. Together with the recent identification of serotype G10P11 newborn rotavirus strains in Bangalore, India (M. Das et al., Virology, 194, 374-379, 1993), these results are consistent with the hypothesis that reassortment may be an important mechanism for generation of rotavirus strains of newborns.

Amino Acid Sequence↗
PubMed1993

Outbreaks of astrovirus gastroenteritis in day care centers.

OBJECTIVE: This study evaluated astrovirus as a cause of diarrhea outbreaks among infants and toddlers in day care centers. DESIGN: Stool specimens were collected weekly during four periods (from January 1986 through December 1991) from children 6 to 30 months of age who were enrolled in prospective studies of diarrhea in day care centers. All diarrheal stool specimens were tested for bacterial enteropathogens, rotavirus, enteric adenovirus, and Giardia lamblia. A total of 1365 stool specimens from 70 outbreaks in which no etiologic agent was identified and from another 11 outbreaks with a known cause were tested for astrovirus, by means of a monoclonal antibody-based enzyme immunoassay. Confirmatory testing was performed by reverse transcriptase-polymerase chain reaction with primers designed to produce an 89 base-pair product. RESULTS: Astrovirus was detected in 6 (7%) of the 81 outbreaks. Of 217 children tested, 73 (34%) were infected with astrovirus; infections in 35 (48%) were symptomatic and in 38 (52%) asymptomatic. The six outbreaks lasted 11 to 44 days (median 22 days). Astrovirus excretion was detected for a duration of 2 to 30 days, with excretion occurring from 1 to 8 days (median 2 days) before diarrhea began to 1 to 20 days (median 2 days) after diarrhea ceased. Younger children (< or = 12 months) were at greater risk than older children (p = 0.011) of becoming infected with astrovirus during an outbreak and were more likely (p = 0.015) to have symptoms when infected. Of 24 specimens with astrovirus by enzyme immunoassay, 20 (83%) were confirmed to have the virus by reverse transcriptase-polymerase chain reaction. CONCLUSION: Astrovirus was an important cause of outbreaks of diarrhea among children attending day care centers, more frequently infected younger children, and often produced asymptomatic infections.

Age Factors↗
PubMed1993

Diarrheal deaths in children living in New Mexico: toward a strategy of preventive interventions.

We reviewed 26 childhood diarrheal deaths examined by the New Mexico Office of the Medical Investigator, from 1980 through 1989, to identify circumstances surrounding the illness that might lead to strategies for prevention. Children who died were younger than 9 months of age (88%) and were from minority groups (American Indian 54%, Hispanic 23%); 12 (46%) had seen a physician within 3 days of death. Interventions to avert these deaths include educating parents to seek earlier treatment and health care providers to recognize that acutely dehydrating diarrhea can be fatal.

Diarrhea, Infantile↗
PubMed1993

Protection conferred by neonatal rotavirus infection against subsequent rotavirus diarrhea.

A cohort of newborns in New Delhi who were nosocomially infected with rotavirus during their first days of life were followed twice weekly for 14-23 months to determine whether neonatal infection protected them against subsequent episodes of rotavirus diarrhea. Infection occurred in 60% by the fourth day of life, was asymptomatic, and was caused predominantly by an unusual rotavirus strain (G9 P11) not previously identified in humans. The 148 children with neonatal rotavirus infection had 46% fewer attacks of rotavirus diarrhea in the follow-up period than the 56 infants without nosocomial infection (0.23 vs. 0.42 episodes/child-year, P < .05). This protection was concentrated among infants in their first year of life and was not associated with a significant decrease in disease severity. Consideration of this strain as a vaccine candidate will require further assessment of its natural protection under field conditions.

Cohort Studies↗
PubMed1993

Cohort study of rotavirus serotype patterns in symptomatic and asymptomatic infections in Mexican children.

A cohort of 200 Mexican children from a low income periurban community was monitored from birth to the age of 2 years to determine the serotype-specific incidence, morbidity and seasonal pattern of symptomatic and asymptomatic human rotavirus (HRV) infections. A total of 177 HRV infections occurred in 134 (67%) children; 50% of these infections were asymptomatic. The incidence of all HRV infections was 0.6 episode/child year and was inversely related to age (r = -0.93; P < 0.01). The incidence of HRV-associated diarrhea was 0.3 episode/child year, with the highest frequency and severity occurring in infants between 4 and 6 months of age. HRV infections were more frequent each autumn, with a changing sequential pattern of predominant serotypes. Overall serotype 3 (34%) was the most frequent, followed by serotypes 1 (16%), 2 (15%) and 4 (6%). The 4 serotypes were associated with a similar risk for diarrhea and severity of diarrhea. In 23 (26%) HRV diarrhea-associated infections, an additional enteropathogen was identified; these mixed infections were more frequent in older children (chi square, 4.45; P < 0.05) but were not more severe (chi square, 0.02; P > 0.05). Our data indicate that HRV infections were common early in life, seasonal, frequently asymptomatic and caused by a variety of serotypes, none of which was a risk factor for diarrhea or severity of diarrhea.

Cohort Studies↗