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Chapter 1 : Novel Non-SARS Coronaviruses
Category: Clinical Microbiology
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This chapter focuses on the novel non-severe acute respiratory syndrome (SARS) coronaviruses (CoVs) associated with human disease. In a study using a fragment of the nucleocapsid protein, it was found that human CoVs (HCoVs) -NL63 antibody positivity was lowest, 5%, at 4 to 5 months of age and then increased to 30% to 40% around 1 year of age and to ~50% at 5 to 10 years of age. A multiplex reverse transcription-PCR assay can allow simultaneous detection of the HCoVs, but in many instances some sensitivity is lost with a multiplex assay compared to single-agent PCR assays. Substantial work has been done on developing vaccines and antiviral drugs for SARS-CoV, and this work could provide a foundation for developing similar products for the HCoVs. Infection control is the one preventive measure that is available for CoVs and has proved effective in helping control SARS-CoV transmission. In a study that included the controls needed to establish an association between detection of the virus(es) and illness, a similar rate of detection was noted in ill and non-ill patients, making it clear that detection does not necessarily indicate a role in disease. The frequent finding of novel CoVs in various species of bats, the availability of very good tools to detect novel viruses, and the range of illness associated with CoVs in different animals suggest that investigators should continue to look for novel CoVs in humans in both respiratory and nonrespiratory illnesses as well as in bats and other animals.
CoV particles. The image is a negative stain electron micrograph of a cell culture isolate of a human SARS-CoV. Note the round structure of the virions with surface projections (similar to rods with knobs at their ends). The bar at the bottom right of the figure represents 100 nm. The isolate was provided by Anthony Sanchez of the Special Pathogens Branch, Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, CDC. The micrograph was prepared by Charles D. Humphrey of the Infectious Disease Pathology Branch, Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, CDC.
Neighbor-joining tree of CoVs based on the alignment of the nucleocapsid protein amino acid sequences. The following Coronavirus members are included in the alignment. Group 1 viruses: human CoVs HCoV-229E and HCoV-NL63; porcine epidemic diarrhea virus (PEDV); feline enteric coronavirus (FECoV); feline infectious peritonitis virus (FIPV); porcine transmissible gastroenteritis virus (TGEV); canine coronavirus (CCoV); bat CoVs bat HKU7, bat HKU8, and bat HKU2, bat CoV1A and bat CoV1B, and bat 512. Group 2 viruses: human CoVs HCoV-OC43 and HCoV-HKU1; rat CoV (RCoV); human Urbani strain of SARS-CoV (SARS CoV); palm civet SARS-CoVs (PC413 and SZ3); bat SARS-CoV-like CoVs RF1, HKU3, RP3, 273, and 279; bat CoVs 133, HKU4, HKU5, and HKU9; porcine hemagglutinating encephalomyelitis virus (PHEV); bovine CoV (BCoV); murine hepatitis virus (MHV); puffinosis CoV (PUCoV); equine CoV (ECoV). Group 3 viruses: avian infectious bronchitis virus (AIBV); turkey CoV (TCoV); pigeon CoV (PICoV).
Species-specific coronavirus infections