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P A Offit

Publications and source records attributed to P A Offit.

69 records · Page 4Linked to original sources
PubMed1986

Identification of the two rotavirus genes determining neutralization specificities.

Bovine rotavirus NCDV and simian rotavirus SA-11 represent two distinct rotavirus serotypes. A genetic approach was used to determine which viral gene segments segregated with serotype-specific viral neutralization. There were 16 reassortant rotaviruses derived by coinfection of MA-104 cells in vitro with the SA-11 and NCDV strains. The parental origin of reassortant rotavirus double-stranded RNA segments was determined by gene segment mobility in polyacrylamide gels and by hybridization with radioactively labeled parental viral transcripts. We found that two rotavirus gene segments found previously to code for outer capsid proteins vp3 and vp7 cosegregated with virus neutralization specificities.

Animals↗
PubMed1986

Molecular basis of rotavirus virulence: role of gene segment 4.

Bovine rotavirus NCDV and simian rotavirus SA-11 exhibited markedly different patterns of gastrointestinal tract disease when inoculated orally into newborn mice. A genetic approach was used to define the molecular basis of these differences. The SA-11 strain of rotavirus was more virulent than the NCDV strain when inoculated orally into newborn mice; the dose of SA-11 required to cause diarrhea in 50% of infant mice was 50-fold less than that required for NCDV. Nineteen reassortant viruses were derived by coinfection of MA-104 cells in vitro with the SA-11 and NCDV strains. The parental origin of reassortant virus double-stranded RNA segments was determined by gene segment migration differences in polyacrylamide gels and hybridization with radioactively labeled parental viral transcripts. The neutralization antigen phenotype of reassortant viruses was determined by plaque reduction neutralization. We found that the dose of SA-11 and NCDV rotavirus required to induce gastroenteritis in newborn mice was determined by gene segment 4. The results suggest that rotavirus virulence may be manipulated by modification or reassortment of gene segment 4.

Antigens, Viral↗
PubMed1986

Passive protection against rotavirus-induced diarrhea by monoclonal antibodies to surface proteins vp3 and vp7.

Monoclonal antibodies directed against two rotavirus surface proteins (vp3 and vp7) as well as a rotavirus inner capsid protein (vp6) were tested for their ability to protect suckling mice against virulent rotavirus challenge. Monoclonal antibodies to two distinct epitopes of vp7 of simian rotavirus strain RRV neutralized RRV in vitro and passively protected suckling mice against RRV challenge. A monoclonal antibody directed against vp3 of porcine rotavirus strain OSU neutralized three distinct serotypes in vitro (OSU, RRV, and UK) and passively protected suckling mice against OSU, RRV, and UK virus-induced diarrhea. The role of vp3 in eliciting protection against heterotypic rotavirus challenge should be considered when developing a vaccine with cloned rotavirus genes. Alternatively, immunization with a reassortant rotavirus containing vp3 and vp7 from two antigenically distinct rotavirus parents might protect against diarrhea induced by two or more rotavirus serotypes.

Animals↗
PubMed1986

Reassortant rotaviruses containing structural proteins vp3 and vp7 from different parents induce antibodies protective against each parental serotype.

Genetic studies of reassortant rotaviruses have demonstrated that gene segments 4 and 9 each segregate with the serotype-specific neutralization phenotype in vitro. Reassortant rotaviruses derived by coinfection of MA-104 cells with the simian strain SA11 and the antigenically distinct bovine strain NCDV were used to determine which viral genes coded for proteins which induced a protective immune response in vivo. In addition, reassortant rotaviruses containing only the gene segment 4 or 9 protein products (vp3 and vp7, respectively) from SA11 or NCDV were used to determine the serotypic specificities of both vp3 and vp7 in several mammalian rotavirus strains. vp3 and vp7 from the murine strain Eb were shown to be indistinguishable from the corresponding proteins from strain SA11. Adult mice orally inoculated with strain Eb developed neutralizing antibodies to both vp3 and vp7. The two naturally occurring bovine rotavirus strains NCDV and UK were shown to contain antigenically similar vp7 but distinct vp3 proteins. Mouse dams orally immunized with a reassortant virus containing only gene 9 from NCDV passively protected their progeny against UK challenge, whereas mouse dams orally immunized with a reassortant virus containing only gene 4 from NCDV did not. Finally, we constructed reassortant viruses that immunized against rotaviruses of two distinct serotypes. SA11 X NCDV reassortants that contained vp3 and vp7 from different parents induced a protective immune response against both parental serotypes. vp3 and vp7 were independently capable of inducing a protective immune response after oral immunization. An understanding of the serotypic specificities of both vp3 and vp7 of human rotavirus isolates will be necessary for the development of successful strategies to protect infants against severe rotavirus infections.

Animals↗
PubMed1985

Maternal antibody-mediated protection against gastroenteritis due to rotavirus in newborn mice is dependent on both serotype and titer of antibody.

In order to evaluate the role of passively acquired, rotavirus-specific antibodies in protection against diarrhea, we inoculated mouse dams with rotaviruses of various serotypes, and their newborns were orally challenged with a primate rotavirus (simian SA-11). Dams were immunized by using a regimen that included repeated inoculations administered either orally or intraperitoneally with adjuvant. The serum antibody response detected in dams by radioimmunoassay and plaque-reduction neutralization after parenteral immunization was approximately 15-fold and 80-fold greater, respectively, than that found after oral "hyperimmunization." Parenteral immunization with rotavirus serotypes either homotypic or heterotypic to the challenge virus protected suckling mice against diarrhea; protection was closely correlated with the in vitro neutralizing activity of maternal serum against the challenge virus. Oral immunization with only rotavirus strains homotypic to the challenge virus afforded protection; the lower immune response after oral immunization with rotaviruses heterotypic to the challenge virus resulted in a titer of neutralizing antibody to the challenge virus below the protective threshold. From our current studies it appears that antibody-mediated passive protection against rotavirus challenge is dependent on both serotype and titer of antibody.

Animals↗
PubMed1985

Protection against rotavirus-induced gastroenteritis in a murine model by passively acquired gastrointestinal but not circulating antibodies.

Newborn mice suckled on dams immunized either orally or parenterally with primate rotavirus SA-11 were protected against diarrhea induced by SA-11 virus challenge. Experimental oral administration of milk from orally immunized dams protected suckling mice against challenge; protective activity was detected both in the anti-rotavirus immunoglobulin A (IgA) and IgG fractions, but IgA was more potent in vivo than IgG. Oral administration of milk from parentally immunized dams also protected suckling mice against challenge; in this case, protective activity was detected in the anti-rotavirus IgG fraction. In newborn mice foster-nursed by seronegative dams, circulating rotavirus-specific antibodies in high titer did not protect mice against oral SA-11 virus challenge. It appears that the most effective rotavirus vaccine will be that which induces an efficient production of antibodies active at the intestinal cell surface.

Animals↗
PubMed1984

Rotavirus-specific antibodies in fetal bovine serum and commercial preparations of serum albumin.

Rotavirus-specific antibodies were detected in fetal bovine serum, bovine serum albumin, and human serum albumin by radioimmunoprecipitation with the NCDV strain of bovine rotavirus as the detecting antigen. Fetal bovine sera neutralized bovine rotavirus in a plaque reduction neutralization test to titers of 1:20 or greater. Immunoglobulins purified from fetal bovine serum by protein A-agarose affinity chromatography precipitated rotavirus antigens but did not neutralize bovine rotavirus. Rotavirus antibodies in fetal bovine serum and in purified serum albumin preparations may interfere with diagnostic assays for the detection of rotavirus antigens or antibodies.

Animals↗
PubMed1984

A murine model for oral infection with a primate rotavirus (simian SA11).

Simian rotavirus SA11 was shown to replicate in the gastrointestinal tracts of infant mice after oral inoculation. Clinical symptoms, histopathological changes in the small intestinal mucosa, and the type-specific humoral immune response were all characteristic of rotavirus-induced gastroenteritis. The availability of this small animal model for the study of a primate rotavirus infection should expedite analysis of the immune response necessary for protection against challenge.

Animals↗
PubMed1983

The cultivation of human rotavirus, strain 'Wa', to high titer in cell culture and characterization of the viral structural polypeptides.

The structural proteins of the 'Wa' (serotype 2) strain of human rotavirus have not been described previously. Single-cycle virus growth in MA-104 cells using 5 micrograms/ml of trypsin in the growth medium was rapid with maximal viral yields (approximately 10(6) PFU/ml) obtained 10-12 h post-infection. There was a continuous progression of cytopathic effect (CPE) from 6- to 5-h post-infection. Under conditions of multiple-cycle growth, a greater concentration of trypsin (40 micrograms/ml) in the growth medium was required to obtain rapid progression of CPE and production of a high titer (approximately 10(7) PFU/ml) of infectious (double-shelled) virus. Single- and double-shelled virions were separated by isopycnic centrifugation in CsCl and analyzed by SDS-PAGE. Five proteins with molecular weights of 116,000, 92,000, 88,000, 84,000 and 41,000 were identified as components of the inner shell and four proteins with molecular weights of 60,000, 38,000, 32,000 and 27,000 were located in the outer shell.

Animals↗
PubMed1983

Response of mice to rotaviruses of bovine or primate origin assessed by radioimmunoassay, radioimmunoprecipitation, and plaque reduction neutralization.

Sera from (i) gnotobiotic BALB/c, CD-1, and CFW mice and (ii) conventional BALB/c mice were evaluated by radioimmunoassay, radioimmunoprecipitation, and plaque reduction neutralization, using the Wa, SA-11, and WC-3 (bovine) strains of rotavirus as the detecting antigens. The gnotobiotic mice had no antirotavirus antibody detectable by radioimmunoprecipitation and no neutralizing antibody at a dilution of 1:50 by plaque reduction neutralization. All sera from the conventional mice had rotavirus-specific antibodies detected by radioimmunoassay and by radioimmunoprecipitation at serum dilutions of 1:50 and 1:10,000, respectively. The antibodies were directed against viral proteins p116, p94, p88, and p84 of all three viruses, but had no neutralizing activity against heterologous rotaviruses at a dilution of 1:50. Conventional seropositive mice were parenterally immunized with the Wa, SA-11, or WC-3 strain of rotavirus. An approximate 100-fold increase in rotavirus-specific antibodies was detected by radioimmunoassay, and greater than 20-fold selective neutralization of the immunizing strain of virus was observed. Sera from the mice immunized with Wa virus had antibodies directed against inner and outer capsid proteins of all three rotaviruses. The mouse can be a useful model for studying the immune response to heterologous rotavirus infection; preexisting antibodies presumably directed towards murine rotavirus do not prevent the development of a type-specific immune response to a nonmurine rotavirus.

Animals↗
PubMed1982

Viral diseases: infections of the gastrointestinal tract.

In the 1970s investigations generated a remarkable amount of information on the viruses responsible for acute gastroenteritis. The two viruses responsible for most cases occur in epidemiologically distinct clinical forms. Although occasionally epidemic, rotavirus infections are usually sporadic and primarily affect infants and young children. This illness is characterized by severe diarrhea commonly lasting five to eight days and frequently associated with upper respiratory tract symptoms, fever, and vomiting. The Norwalk agent and Norwalk-like viruses are characteristically epidemic and responsible for community-wide outbreaks of gastroenteritis among all ages. The disease this agent produces usually lasts 24 to 48 hours and is characterized by various combinations of vomiting, diarrhea, nausea, headache, and low-grade fever.

Adult↗
PubMed1981

Severe Epstein-Barr virus pulmonary involvement.

Two cases of severe Epstein-Barr virus (EBV) pulmonary involvement are described. Both were documented by EBV-specific serology and other causes of respiratory tract infection were excluded by culture and serology. Our first case describes fatal infectious mononucleosis (IM) with severe pneumonia in a patient without a definable immunologic disorder. Previous cases of pulmonary involvement in IM are reviewed.

Adolescent↗
PubMedDate not supplied

Specific attachment of aqueous-based microcapsules to macrophages, B cells, and dendritic cells in vitro.

Microcapsules were previously prepared composed of aqueous anionic polymers (e.g. alginate) and aqueous amines (e.g. spermine) and it was found that the aqueous-based microcapsules enhanced rotavirus-specific immune responses after oral or parenteral immunization of mice. In these studies, one has modified the amine moiety of aqueous-based microcapsules to bind covalently to avidin and the avidin-bearing microcapsules were linked to biotinylated antibodies specific for surface markers on murine macrophages, dendritic cells, or B cells. Using fluorescence flow cytometry, it was found that antibody-coated microcapsules bound specifically to antigen-presenting cells (APC) in vitro. The availability of APC-specific microcapsules should allow for the uptake of antigens by specific APC, and further one's understanding of the relative capacities of different APC to induce antigen-specific immune responses.

Animals↗