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Biological and genetic characterization of a hemagglutinating coronavirus isolated from a diarrhoeic child
X M Zhang1, W Herbst, K G Kousoulas
1Department of Veterinary Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State University, Baton Rouge.
Insights
A novel hemagglutinating enteric coronavirus (HECV-4408) was identified in a child with acute diarrhea. This enteric coronavirus is biologically, antigenically, and genetically more similar to virulent bovine coronavirus (BCV-LY138) than to human coronavirus OC43 (HCV-OC43).
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Human enteric coronaviruses (HECVs) are significant causes of gastroenteritis in children.
- Characterization of novel HECV strains is crucial for understanding viral pathogenesis and epidemiology.
- Previous studies have identified various HECV strains with differing characteristics and clinical associations.
Observation:
- A novel coronavirus strain, HECV-4408, was isolated from a child with acute diarrhea and propagated in HRT-18 cells.
- Electron microscopy confirmed the presence of coronavirus particles in clinical samples and cell cultures.
- HECV-4408 exhibited hemagglutinating and acetylesterase activities and caused specific cytopathic effects in HRT-18 cells.
Findings:
- Monoclonal antibody analysis indicated partial antigenic similarity between HECV-4408, BCV-L9, and BCV-LY138, but distinctness from HCV-OC43.
- Genomic analysis of the 3' end revealed similarities between HECV-4408, BCV-L9, and BCV-LY138, with notable differences in the M gene and a lack of genomic deletion compared to HCV-OC43.
- High nucleotide and amino acid homology (over 99%) were found between HECV-4408 and BCV, with HECV-4408 showing greater similarity to BCV-LY138 than to HCV-OC43 based on HE gene sequences.
Implications:
- HECV-4408 represents a distinct hemagglutinating enteric coronavirus.
- The findings suggest a closer evolutionary relationship between HECV-4408 and bovine coronavirus (BCV) strains than with human coronavirus OC43 (HCV-OC43).
- Further research into HECV-4408 can provide insights into the genetic diversity and interspecies transmission potential of enteric coronaviruses.
Abstract:
The coronavirus strain HECV-4408 was isolated from diarrhea fluid of a 6-year-old child with acute diarrhea and propagated in human rectal tumor (HRT-18) cells. Electron microscopy revealed coronavirus particles in the diarrhea fluid sample and the infected HRT-18 cell cultures. This virus possessed hemagglutinating and acetylesterase activities and caused cytopathic effects in HRT-18 cells but not in MDBK, GBK and FE cells. One of four S-specific monoclonal antibodies reacted in Western blots with HECV-4408, BCV-L9 and BCV-LY138 but not with HCV-OC43, and two reacted with BCV-L9 but not with HECV-4408, BCV-LY138 and HCV-OC43. One S-specific and two N-specific monoclonal antibodies reacted with all of these strains. cDNA encompassing the 3' 8.5 kb of the viral RNA genome was isolated by reverse transcription followed by polymerase chain reaction amplification had size and restriction endonuclease patterns similar to those of BCV-L9 and BCV-LY138. In contrast, the M gene of HCV-OC43 differed in restriction patterns from HECV-4408 and BCV. A genomic deletion located between the S and M within the non-structural genes of HCV-OC43 was not detected in HECV-4408. DNA sequence analyses of the S and HE genes revealed more than 99% nucleotide and deduced amino acid homologies between HECV-4408 and the virulent wild-type BCV. Forty-nine nucleotide and 22 amino acid differences were found between the HE genes of HECV-4408 and HCV-OC43, while only 16 nucleotide and 3 amino acid differences occurred between the HE genes of HECV-4408 and BCV-LY138. We thus conclude that the strain HECV-4408 is a hemagglutinating enteric coronavirus that is biologically, antigenically and genomically more closely related to the virulent BCV-LY138 than to HCV-OC43.