Feline coronaviruses (FCoV) comprise two biotypes: feline enteric coronaviruses (FECV) and feline infectious peritonitis viruses (FIPV). FECV is associated with asymptomatic persistent enteric infections, while FIPV causes feline infectious peritonitis (FIP), a usually fatal systemic disease in domestic cats and some wild Felidae. FIPV arises from FECV by mutation. FCoV also occur in two serotypes, I and II, of which the serotype I viruses are by far the most prevalent in the field. Yet, most of our knowledge about FCoV infections relates to serotype II viruses, particularly about the FIPV, mainly because type I viruses grow poorly in cell culture. Hence, the aim of the present work was the detailed study of the epidemiologically most relevant viruses, the avirulent serotype I viruses. Kittens were inoculated oronasally with different doses of two independent FECV field strains, UCD and RM. Persistent infection could be reproducibly established. The patterns of clinical symptoms, faecal virus shedding and seroconversion were monitored for up to 10 weeks revealing subtle but reproducible differences between the two viruses. Faecal virus, i.e. genomic RNA, was detected during persistent FECV infection only in the large intestine, downstream of the appendix, and could occasionally be observed also in the blood. The implications of our results, particularly our insights into the persistently infected state, are discussed.
OBJECTIVE: To perform quality assessment of standardized random amplified polymorphic DNA (RAPD) analysis for epidemiologic typing of Klebsiella pneumoniae, K. oxytoca, Serratia marcescens and Pseudomonas aeruginosa. METHODS: Thirty K. pneumoniae, 15 K. oxytoca, 30 S. marcescens and 33 P. aeruginosa epidemiologically unrelated isolates and four collections of clinically related isolates of each species were included in the study. RAPD analysis was performed using Ready-To-Go RAPD Analysis beads with primer ERIC-1R and Ready-To-Go primer 2 for K. pneumoniae and K. oxytoca, primer set ERIC-2/1026 and Ready-To-Go primer 2 for S. marcescens, and primers D-10514 and D-14306 for P. aeruginosa. RESULTS: All epidemiologically unrelated K. pneumoniae and K. oxytoca isolates were distinguished. Twenty-nine types were distinguished among the 30 unrelated S. marcescens isolates and 32 types among the 33 unrelated P. aeruginosa isolates. Indistinguishable banding patterns were obtained in repeated analyses of two isolates and from 11 serial subcultures of three isolates of each species included in the study. The RAPD data from the clinically related isolates correlated with the epidemiologic origin of the isolates. CONCLUSIONS: The use of Ready-To-Go RAPD Analysis beads resulted in reproducible and stable banding patterns with a high discriminatory capacity, and the RAPD typing results corresponded with the epidemiologic origin of the isolates.
Antigenic drift of the major outer membrane protein (MOMP) P2 of nonencapsulated Haemophilus influenzae as observed during persistent infections in patients with chronic bronchitis was mimicked in a rabbit model in which H. influenzae persisted in subcutaneous cages. The antigenic drift resulted from amino acid substitutions in potentially surface-exposed loops of MOMP P2. Since in a rabbit model the appearance of antigenic variants was associated with the presence of strain-specific bactericidal antibodies (L. Vogel, B. Duim, F. Geluk, P. Eijk, H. Jansen, J. Dankert, and L. van Alphen, Infect. Immun. 64:980-986, 1996), we determined the epitope specificities of these bactericidal antibodies. The eight loops of MOMP P2 of H. influenzae d1 were separately expressed as fusion proteins with glutathione S-transferase. Sera of rabbits persistently infected with H. influenzae reacted with the loop 5 and loop 6 fusion proteins in immunoblotting and enzyme-linked immunosorbent assay. For fine mapping of the epitopes with pepscan analysis, overlapping synthetic peptides consisting of 12 amino acids were made. Rabbit sera contained antibodies reacting with peptides derived from loop 5 and peptides containing amino acids of the side of loop 6. In addition, MOMP P2 variant-specific reactions with the amino acids located at the tip of loop 6 were detected. The rabbit sera showed variantspecific complement-dependent bactericidal activities, which were eliminated by affinity chromatography with fusion proteins of loop 6 but not of loop 5. We conclude that, during persistence of H. influenzae in rabbits, variant-specific bactericidal antibodies are elicited to the variable tip of MOMP P2 loop 6.
During persistence of nonencapsulated Haemophilus influenzae in the respiratory tracts of patients with chronic bronchitis, the major outer membrane proteins (MOMPs) P2 and P5 show antigenic drift. The hypothesis that appearance of antigenic variants is the consequence of antibody-dependent selection was tested in a rabbit model. Persistence of H. influenzae d1 was achieved in subcutaneous tissue cages for up to 948 days. During persistence in the rabbits, similar changes in MOMP P2 of H. influenzae occurred, as observed in isolates from chronic bronchitis patients. In rabbits vaccinated with strain d3 and in nonvaccinated rabbits, antigenic drift occurred later than in rabbits vaccinated with strain d1. High titers of antibodies against H. influenzae were measured in tissue cage fluid and serum. Vaccination of the rabbits with H. influenzae d1 or d3, an antigenic variant of strain d1, resulted neither in eradication of H. influenzae d1 nor in increased antibody titers in serum and tissue cage fluid. The sera of nonvaccinated rabbits during persistence had no strain d1-specific bactericidal activity in the presence of complement. Vaccination with H. influenzae d1 induced serum bactericidal activity against strain d1 in the presence of complement. However, a variant of strain d1 appearing in the tissue cages was not killed by this serum bactericidal activity. We conclude that immunological pressure leads to the selection of MOMP variants of H. influenzae and that these variants escape the antibody-mediated strain-specific bactericidal activity against H. influenzae.
Objective To compare random amplified polymorphic DNA (RAPD) analysis and ribotyping with serotyping for epidemiologic typing of Escherichia coli.Methods Thirty-two epidemiologically unrelated strains, nine cerebrospinal fluid isolates with the O7K1 serotype from nine patients, and nine sets of epidemiologically related E. coli isolates from nine patients were typed by RAPD analysis, ribotyping and serotyping. ResultsAmong the 32 epidemiologically unrelated E. coli isolates, 29 types were distinguished by RAPD analysis, 25 by ribotyping and 27 by serotyping. Indistinguishable patterns were obtained by RAPD analysis and ribotyping within the collection of nine cerebrospinal fluid isolates. For the epidemiologically related isolates, intrapatient variation was only found by RAPD analysis among the isolates of one set and by ribotyping among the isolates of two sets. No interpatient variation was observed between three sets of isolates. With serotyping, the epidemiologically related isolates yielded similar typing relationships to those obtained by RAPD analysis and ribotyping.Conclusions RAPD analysis had the highest discriminatory capacity for typing E. coli isolates. RAPD analysis, ribotyping and serotyping can all be used for assessment of strain relationships.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.