Biomedical subjects

D O Matson

Publications and source records attributed to D O Matson.

At least 55 records · Page 3Linked to original sources

PubMed1996

Outbreaks of gastroenteritis in elderly nursing homes and retirement facilities associated with human caliciviruses.

Eleven outbreaks of acute gastroenteritis, eight of which were in nursing homes or retirement facilities, were reported in virginia during the winter of 1993-1994. Serum samples (four outbreaks) and stool samples (two outbreaks) from involved people were tested for human calicivirus (HuCV) infection by enzyme immune assays (EIAs) using recombinant Norwalk virus (rNV) and Mexico virus (rMX) capsid antigens and reverse transcription-polymerase chain reaction (RT-PCR). Of the 31 pairs of acute and convalescent serum specimens tested, 24 had a fourfold or more titer increase to rMX and 4 responded to rNV. In all four outbreaks, the geometric mean titers (GMTs) against rMX were significantly higher than those against rNV in the convalescent, but not in the acute phase of illness. The antibody response to rMX among these patients was also higher than to rNV (summary mean 32-fold increase vs. 0.7-fold increase, respectively, P < .001). Antigen was detected in 5 of 21 stool specimens tested by the rMX EIA, RNA in 12 of 17 stool specimens tested by RT-PCR, and small round structured virus (SRSV) particles in 12 of 21 by electron microscopy (EM); none were positive by the rNV EIA. Sequence analysis of the RT-PCR-amplified products from the viral RNA polymerase region revealed 92-93% amino acid identity with Snow Mountain agent (SMA), 86% with MX, 58-59% with NV, and 31-32% with Sapporo HuCV, suggesting that these viruses belong to the SMA HuCV genogroup.

Aged↗

PubMed1996

Protective immunity against group A rotavirus infection and illness in infants.

Understanding of the protective effect provided by natural rotavirus infections against subsequent rotavirus infections is required for evaluating vaccine development programs. Prior studies of the protective efficacy of natural infections and correlates of natural protection are reviewed and results from several studies presented only in abstract form are summarized to provide a current assessment of knowledge in this area. Six cohort studies have reported rates for the protective efficacy of a natural rotavirus infection against subsequent infection, diarrhea, or severe diarrhea. These efficacy estimates ranged from 0 to 100% and are not directly comparable because of differences in methodology and population monitored. Results from other study designs also have been confusing, until recently. Recent studies have identified immunologic correlates of protection and studies from a cohort of intensely monitored Mexican children promise to provide a comprehensive assessment of the strength of the protective effect of natural rotavirus infection.

Animals↗

PubMed1996

Genetic and antigenic diversity of human caliciviruses (HuCVs) using RT-PCR and new EIAs.

RT-PCR using primers from conserved regions of calicivirus genomes, followed by sequencing, permits characterization of genetic variation within the family. EIAs based on baculovirus-expressed viral capsid proteins and hyperimmune antisera against the capsid proteins were developed to detect HuCV antigens and antibodies. Serologic surveys using recombinant Norwalk virus (rNV) and recombinant Mexico virus (rMX, a SMA-like virus) EIAs showed that infections by HuCVs are common and that children acquire antibodies to HuCVs at an early age in both developed and developing countries. Three HuCV genogroups have been described that are represented by Norwalk virus (NV), Snow Mountain agent (SMA), and Sapporo virus, although recently accumulated sequences of HuCV strains indicate these genogroups can be further divided. These genogroups also correspond to distinct antigenic groups based on the results of the recombinant EIAs. The three genogroups co-circulate and have a worldwide distribution, although the SMA genogroup seems to be predominant currently. Application of these new assays for further characterization of the genetic and antigenic properties of HuCVs remains an important task for HuCV research.

Antibodies, Viral↗

PubMed1996

The epidemiology of human calicivirus/Sapporo/82/Japan.

Based on genome analysis of the RNA-dependent RNA polymerase region, it has been proposed that human caliciviruses (HuCV) can be classified into at least three genogroups: genogroup I is represented by Norwalk virus (NV), genogroup II by Snow Mountain agent (SMA) and genogroup III by HuCV/Sapporo/82/Japan (HuCV/Sa/82/J) virus. HuCV/Sa/82/J strain is genetically unique and more closely related to animal caliciviruses than are other known HuCVs, such as NV and SMA. HuCV/Sa/82/J strain was detected in four outbreaks of HuCV gastroenteritis occurring between 1977 and 1982 in an infant home in Sapporo. The HuCVs detected from these four outbreaks all showed a typical "Star of David" configuration by electron microscopy (EM), and they were identical antigenically and genetically. This strain has also been detected in other prefectures in Japan, as well as in the USA, UK, Saudi Arabia and Kenya. Seroepidemiological studies have shown a worldwide distribution of this virus, including Japan, USA, UK, Southeast Asia, Canada, China and Kenya. This virus has been circulating in Sapporo for at least 19 years (1977-1995). HuCV/Sa/82/J strain is thought to be one of the common causes of viral gastroenteritis worldwide. The HuCV/Sa/82/J strain has been detected mainly in infants. Age-related prevalence of antibody to this strain also shows that infections commonly occur in children less than 5 years old, although viruses in the NV and SMA genogroups commonly infect adults. The pattern of acquisition of antibodies to strain HuCV/Sa/82/J is similar to that of other common viral infections. HuCV/Sa/82/J strain is unique virologically and clinically among caliciviruses.

Age Factors↗

PubMed1996

Dot blot hybridization with a cDNA probe derived from the human calicivirus Sapporo 1982 strain.

A dot blot hybridization assay was developed for detection of human calicivirus/Sapporo/82/J (HuCV/Sa/82) or strains closely related to HuCV/Sa/82 in stool specimens. The cDNA derived from the RNA-dependent RNA polymerase (RDRP) region of HuCV/Sa/82 was used as a positive probe and the pBR322 DNA as a negative control probe. Both probes were labeled with digoxigenin and the products of hybridization reaction were detected with an anti-digoxigenin antibody-alkaline phosphatase conjugate. This assay was specific for HuCV/Sa/82 and for HuCV antigenically related to HuCV/Sa/82. The lower limit of sensitivity of this assay was estimated to be about 10(5) physical particles or 10 pg of cDNA, similar to that of the previously developed ELISA for HuCV. In 1273 stool specimens obtained from children with acute gastroenteritis in Sapporo, Japan, 110 (8.6%) contained small round structured viruses by EM and 23 (1.8%) were positive for HuCV antigenically related to HuCV/Sa/82 by either the hybridization assay or ELISA. A higher positive rate was obtained with the dot blot assay (21%) than by ELISA (10%), suggesting that the dot blot assay either detects HuCV more broadly than the ELISA or detects HuCV covered with fecal antibodies which interrupt antigen-antibody reactions in the ELISA. Negative results for detection of Norwalk virus (NV) cDNA and feline calicivirus (FCV) RNA by both this assay and the ELISA indicated that the HuCV/Sa/82 strain is distinct antigenically and genetically from NV and FCV.

Acute Disease↗

PubMed1996

Partial characterization of the genome of nine animal caliciviruses.

Caliciviruses (CVs) include at least 42 distinct serotypes. Seventeen CV serotypes have been isolated from marine sources and are called San Miguel sea lion caliciviruses (SMSVs). CVs also have been isolated from reptiles, primates, and other terrestrial animals. Nucleotide sequences from portions of genome of prototype strains for six SMSV serotypes, the reptile CV, Cro-1, the cetacean CV, Tur-1, and the primate CV, Pan-1, are presented. cDNA products of the polymerase (all strains characterized) and capsid (SMSV-17) regions were produced by reverse transcription-polymerase chain reaction using Pan-1 primers. Comparisons of nucleotide and amino acid identity among these and published CV sequences indicated that the nine characterized CVs fall into a phylogenetic group that includes SMSV-1 and SMSV-4 and that is more closely related to other characterized animal CVs than to most human CVs. The phylogenetic analysis also indicated that distinct genera exist among the Caliciviridae. SMSV-17 and SMSV-4 are predicted to be closer to each other than other caliciviruses of known serotype; 574 (82%) of the 704 amino acids in the SMSV-17 and SMSV-4 capsid genes were identical.

Amino Acid Sequence↗

PubMed1995

Molecular characterization of a human calicivirus with sequence relationships closer to animal caliciviruses than other known human caliciviruses.

cDNA clones were produced from a morphologically typical human calicivirus (HuCV) in stool specimens collected in 1982 during an outbreak of gastroenteritis in Sapporo, Japan. The cDNA clones were generated separately in two laboratories by reverse transcriptase-polymerase chain reaction (RT-PCR) using primers 35 and 36 derived from Norwalk virus. The RT-PCR product from six specimens was of the predicted size, had a continuous protein encoding frame on the positive strand, and contained GLPS and YGDD amino acid motifs at the predicted distance from the primers. RT-PCR amplification with primer 35 and a HuCV/Sapporo-specific primer 36 of four HuCV/Sapporo-positive stool specimens from a 1986 Houston day care center outbreak yielded products with 93% nucleotide and 99% predicted amino acid sequence identity with the HuCV/Sapporo strain from the 1982 outbreak. The HuCV/Sapporo strains are genetically distinct from previously characterized HuCVs and more closely related to known animal CVs than other known HuCVs.

Animals↗

PubMed1995

Study of Norwalk-related viruses in Mexican children.

Two-hundred Mexican children monitored from birth to 2 years of age in a cohort study of diarrhea were tested for Norwalk virus (NV) and Norwalk-related virus infection. Blood was collected quarterly and tested by an enzyme immunoassay (EIA) using the recombinant NV (rNV) particles as antigen. Stool was collected weekly and tested by an EIA using hyperimmune anti-sera from animals immunized with rNV and a reverse transcription-polymerase chain reaction (RT-PCR) with primers in the RNA polymerase region of NV. A high prevalence of serum antibody to NV (85% at age 2 years) was found by the antibody EIA. In 54 stool specimens selected from children who developed a high titer of serum antibody to rNV, none was positive for NV by the antigen EIA, but 6 yielded products by the RT-PCR. One stool specimen (MX virus) yielded a 3.3 kb RT-PCR product from the 3' end of the viral genome. The MX virus cDNA has a genomic organization like other caliciviruses. Sequence comparison showed that MX virus shares 80% nucleic acid and 91% amino acid sequence identity with Snow Mountain agent (SMA), but only 62% and 60% identity, respectively, with NV in the RNA polymerase region, suggesting that MX virus is a SMA-like virus.

Amino Acid Sequence↗

PubMed1995

Group A rotavirus G type prevalence in two regions of Hungary.

Rotaviruses are a major cause of gastroenteritis in children world-wide. Rotaviruses are antigenically complex, with multiple serotypes (G types). The first longitudinal study of group A rotavirus serotype (G type) distribution in Hungary is reported. Neutralizing monoclonal antibodies specific for G1, G2, G3, and G4 were used in an enzyme immunoassay to determine the antigenic variation of group A rotaviruses in two collections of stool specimens assembled from 1984-1992 in Baranya County, southwest Hungary, and from 1988-1992 at the Central Hospital for Infectious Diseases in Budapest. Ninety-two percent of the 1215 virus-positive samples were typed as follows: G1 (81%), G2 (4%), G3 (1%), G4 (5%), or mixed type (1%). G1 was the predominant type during the entire study period with the exception of the 1988/1989 rotavirus season in Baranya County when G4 predominated. Among G1 strains, different electropherotypes were detected with a shift of the predominant G1 electropherotype(s) each 2 to 3 years. G typing from two longitudinal collections established regional differences within Hungary in the prevalence of rotavirus antigenic types among children with rotavirus-associated diarrhea. These are the first longitudinal rotavirus typing results for Hungary and Central Europe.

Antibodies, Monoclonal↗

PubMed1995

Effect of maternal rotavirus immunization on milk and serum antibody titers.

This prospective study evaluated human milk and serum antirotavirus antibody concentrations following maternal rotavirus immunization. Postpartum women (33) were randomized into 3 groups and received a single oral dose of rhesus rotavirus monovalent reassortant vaccine (10(4) pfu), tetravalent vaccine (10(4) pfu), or placebo. Milk (secretory [s] IgA) and serum (IgA and IgG) specimens were tested for antirotavirus isotype-specific antibody. Sera also were tested for G1- to G4-specific antibody. Prevaccine milk and serum isotype-specific antibody concentrations were not significantly different in the 3 groups. Postvaccine sIgA log titers were significantly greater in the 2 vaccine groups than the placebo group (P = .002). Mean log10 titers at 1 week were 2.1 (95% confidence interval [CI], 2.0-2.3) in the 2 vaccine groups and 1.7 (95% CI, 1.5-1.9) in the placebo group. Milk titers did not differ between vaccine groups. There was no difference in reactogenicity between groups. The significantly higher milk concentrations of antibody to rotavirus in postpartum women who received rotavirus immunization persisted for 4 months.

Adolescent↗

PubMed1995

Virologic features of an astrovirus diarrhea outbreak in a day care center revealed by reverse transcriptase-polymerase chain reaction.

Astroviruses cause outbreaks of diarrhea in children attending day care centers (DCCs). Reverse transcriptase-polymerase chain reaction (RT-PCR) was compared with EIA detection of astrovirus in stool specimens to characterize further the molecular epidemiology of an outbreak of astrovirus-associated gastroenteritis. Three hundred sixty-eight stool specimens collected prospectively from 36 children enrolled in a DCC during an 11-week outbreak of diarrhea were evaluated by EIA and RT-PCR. Astrovirus was detected in 32% of specimens by RT-PCR versus 10% by EIA (P < .001) and in 89% of children by RT-PCR versus 50% by EIA. The median duration of astrovirus excretion episodes detected by EIA was 1.5 days versus 4 days by RT-PCR (P = .06). Astrovirus was excreted for prolonged periods by immunocompetent children during this outbreak. RT-PCR was more sensitive than EIA for detection of astrovirus in stool specimens and redefined the epidemiology of astrovirus infection in this setting.

Age Factors↗

PubMed1995

Development of an ELISA to detect MX virus, a human calicivirus in the snow Mountain agent genogroup.

MX virus is a Snow Mountain agent (SMA) genogroup human calicivirus (HuCV) identified in a Mexican child with diarrhoea. An ELISA using hyperimmune antisera to the recombinant MX virus (rMX) capsid was developed to detect SMA genogroup HuCVs in stool specimens. The rMX ELISA detected the prototype MX virus, SMA, and Hawaii agent (HA), but not Norwalk virus (NV) or Sapporo virus. Twenty-three diarrhoea stool specimens from children attending day care centres in Norfolk, Virginia, were positive by the rMX ELISA and results were confirmed by reverse transcription-polymerase chain reaction (RT-PCR). Eight of 20 diarrhoea stool specimens from children in the United Kingdom previously shown to contain small round structured viruses (SRSVs) or HuCVs by electron microscopy were also positive by the rMX ELISA and RT-PCR. Sequence analysis of the RT-PCR products showed that all the rMX ELISA-positive viruses belong to the SMA genogroup. These data also showed that the SMA genogroup can be further divided into two subgroups: subgroup 1 includes prototypes SMA and HA, and subgroup 2 includes MX virus, minireovirus, Oth-25 and Bristol virus.

Animals↗

PubMed1995

Expression, self-assembly, and antigenicity of a snow mountain agent-like calicivirus capsid protein.

Virus-like particles were produced in insect cells infected with a recombinant baculovirus containing the capsid gene of MX virus, a Mexican strain of human calicivirus. These recombinant MX (rMX) particles were morphologically similar to recombinant Norwalk virus (rNV) particles as observed under an electron microscope and contained a single capsid protein with a molecular weight of 57,000, which was slightly smaller than that of rNV. This protein was immunoprecipitated by sera from volunteers infected with the Snow Mountain agent, but it reacted weakly with sera from volunteers infected with NV. This protein did not react with hyperimmune antisera from animals immunized with rNV in the rNV antigen enzyme immunoassay (EIA). Seroresponses were detected from volunteers infected with Snow Mountain agent and Hawaii agent when the rMX particles were used as antigen in an EIA. This EIA also detected an immune response in the sera of child from whom the MX virus was isolated, and a high prevalence of antibody to MX virus was found in the sera of a cohort of Mexican children.

Animals↗

PubMed1994

Three-dimensional structure of calicivirus.

The Caliciviridae comprise a new family of single-stranded RNA viruses. While human caliciviruses cause gastroenteritis, the animal caliciviruses cause a wide range of diseases. We have determined the three-dimensional structure of a primate calicivirus using electron cryomicroscopy and computer image-processing techniques. Calicivirus is one of the rare animal viruses whose capsid is made of a single structural protein. The three-dimensional structure of the virus is distinct from that of any other animal virus. However, there are several architectural similarities with plant viruses such as tomato bushy stunt virus and turnip crinkle virus. The calicivirions are 405 A in diameter and exhibit T = 3 icosahedral symmetry. The main features of the three-dimensional structure are the 32 large surface hollows, 50 A deep and 90 A wide, at the icosahedral 5-fold and 3-fold axes, and the 90 distinctive arch-like capsomeres surrounding these hollows at the local and strict 2-fold axes. Each capsomere is a dimer of the capsid protein. Despite noticeable differences, the three quasi-equivalent subunits show common structural features: the upper bilobed domain, the central stem domain, and the lower shell domain. The 2-fold related capsid proteins interact through the bilobed domains to form the top of the arch. The structural differences between the connectors of the stem and the shell domain among the three subunits suggest the presence of a hinge region that may facilitate the capsid protein to adapt to the three quasi-equivalent environments of the T = 3 icosahedral structure. The shell domains of the pentavalent and hexavalent capsid proteins associate to form a continuous shell between the radii of 115 and 150 A. A beta-barrel structure has been suggested for the shell domain. The mass density in the inner shell between the radius of 85 and 110 A may contain a portion of the capsid protein interacting with the RNA. The features between the 45 and 85 A radius are suggestive of ordered RNA.

Animals↗

PubMed1994

Rotavirus vaccines and vaccination potential.

The development of a successful rotavirus vaccine is a complex problem. Our review of rotavirus vaccine development shows that many challenges remain, and priorities for future studies need to be established. For example, the evaluation of administration of a vaccine with OPV or breast milk might receive less emphasis until a vaccine is made that shows clear efficacy against all virus serotypes. Samples remaining from previous trials should be analyzed to determine epitope-specific serum and coproantibody responses to clarify why only some trials were successful. Detailed evaluation of the antigenic properties of the viruses circulating and causing illness in vaccinated children also should be performed for comparisons with the vaccine strains. In future trials, sample collection should include monitoring for asymptomatic infections and cellular immune responses should be analyzed. The diversity of rotavirus serotype distribution must be monitored before, during, and after a trial in the study population and placebo recipients must be matched carefully to vaccine recipients. Epidemiologic and molecular studies should be expanded to document, or disprove, the possibility of animal to human rotavirus transmission, because, if this occurs, vaccine protection may be more difficult in those areas of the world where cohabitation with animals occurs. We also need to have an accurate assessment of the rate of protection that follows natural infections. Is it realistic to try to achieve 90% protective efficacy with a vaccine if natural infections with these enteric pathogens only provide 60% or 70% protection? Subunit vaccines should be considered to be part of vaccine strategies, especially if maternal antibody interferes with the take of live vaccines. The constraints on development of new vaccines are not likely to come from molecular biology. The challenge remains whether the biology and immunology of rotavirus infections can be understood and exploited to permit effective vaccination. Recent advances in developing small animal models for evaluation of vaccine efficacy should facilitate future vaccine development and understanding of the protective immune response(s) (Ward et al. 1990b; Conner et al. 1993).

Animals↗

PubMed1994

Assessment of epitope-blocking assays for measuring antibody to rotavirus.

Criteria for determining the presence of antibody and of a response to infection in the epitope-blocking assay for anti-rotavirus antibody were evaluated using 222 sera from children younger than 30 months of age. The children were monitored for rotavirus diarrhea by means of daily symptom records and weekly stool specimen collection, whether or not symptoms occurred. Sera were collected at 6-month intervals. Forty-three serum pairs were collected before and after documented rotavirus infections. The remaining 136 sera were collected from children with no identified infections in the monitoring interval. Use of a 50% cutoff-point, as in prior reports, was too stringent a criterion for determining the presence of blocking antibody. The absolute percent blocking at the 1:10 serum dilution was a better measure of antibody content than end-point titration using the 50% cutoff-point.

Antibodies, Viral↗

PubMed1994

Anti-rotavirus G type-specific and isotype-specific antibodies in children with natural rotavirus infections.

Serum VP7 (G) type- and isotype-specific anti-rotavirus antibodies were assessed among children monitored longitudinally over one or two rotavirus seasons in day care centers. Seventy-five pairs of blood specimens from 63 children were tested for anti-rotavirus antibodies. Stool specimens were collected weekly and tested for rotavirus antigen. G typing of detected rotaviruses showed that seven outbreaks of G1 and one of G3 occurred during the two seasons. G type-specific responses to the outbreak strain occurred among 79% of infected children and 9% of children with infection not detected (P < .001). Of children infected with G1, 54% had a heterotypic response; they were older (P = .048) and had higher preexisting G1 antibody levels than children who had only homotypic responses (P = .012). Higher IgA, IgG, and homotypic antibody levels to the antigenic site C of the G1 and G3 VP7s correlated with protection against infection and illness, homotypic antibody independently of IgA or IgG titers.

Antibodies, Viral↗

PubMed1994

Acquisition of serum isotype-specific and G type-specific antirotavirus antibodies among children in day care centers.

The acquisition of serum antirotavirus antibodies among children in day care centers was monitored through two rotavirus seasons. Twenty-six children were monitored daily for diarrhea and weekly for stool rotavirus excretion through a rotavirus season of infections with serotype G1 and a successive season of infections with both G1 and G3. Sera were collected before and after each rotavirus season and tested for antirotavirus IgA and IgG and for G type-specific blocking antibody. The prevalence of protective serum IgA and IgG titers increased from 36% and 45% before Season 1 to 77% and 96% after Season 2, respectively (P < 0.02 and 0.001). G type-specific antibodies also increased (G1, P < 0.001; G2, P = 0.005; G3, P = 0.003; G4, P = 0.006), including for noncirculating types. Homotypic and heterotypic antibodies increased as the number of rotavirus infections experienced by a child increased. The group of children with two proven infections developed protective isotype-specific and G type-specific antibodies. These results indicate that in first exposures to rotavirus G types, children develop predominantly homotypic antibody. However, as the number of rotavirus infections increase, children develop heterotypic antibody to G types at levels that correlate with broad protection against rotavirus infection and illness, despite exposure to a restricted number of G types.

Antibodies, Viral↗