Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats

TLDR

SARS‑CoV was first isolated from civets in Chinese live‑animal markets, suggesting civets may have acted only as amplification hosts rather than reservoirs. A surveillance study using RT‑PCR on anal swabs from 59 wild Chinese horseshoe bats detected a SARS‑CoV–related virus (bat‑SARS‑CoV) in 23 samples (39 %). Sequencing revealed that bat‑SARS‑CoV clusters with human and civet SARS‑CoV as a distinct group 2b coronavirus, with notable spike, ORF 3, and ORF 8 differences—including a 29‑bp insertion in ORF 8—while serology showed 84 % of bats had antibodies to bat‑SARS‑CoV and many also neutralized human SARS‑CoV. Precautions should be exercised in handling these animals.

Abstract

Although the finding of severe acute respiratory syndrome coronavirus (SARS-CoV) in caged palm civets from live animal markets in China has provided evidence for interspecies transmission in the genesis of the SARS epidemic, subsequent studies suggested that the civet may have served only as an amplification host for SARS-CoV. In a surveillance study for CoV in noncaged animals from the wild areas of the Hong Kong Special Administration Region, we identified a CoV closely related to SARS-CoV (bat-SARS-CoV) from 23 (39%) of 59 anal swabs of wild Chinese horseshoe bats ( Rhinolophus sinicus ) by using RT-PCR. Sequencing and analysis of three bat-SARS-CoV genomes from samples collected at different dates showed that bat-SARS-CoV is closely related to SARS-CoV from humans and civets. Phylogenetic analysis showed that bat-SARS-CoV formed a distinct cluster with SARS-CoV as group 2b CoV, distantly related to known group 2 CoV. Most differences between the bat-SARS-CoV and SARS-CoV genomes were observed in the spike genes, ORF 3 and ORF 8, which are the regions where most variations also were observed between human and civet SARS-CoV genomes. In addition, the presence of a 29-bp insertion in ORF 8 of bat-SARS-CoV genome, not in most human SARS-CoV genomes, suggests that it has a common ancestor with civet SARS-CoV. Antibody against recombinant bat-SARS-CoV nucleocapsid protein was detected in 84% of Chinese horseshoe bats by using an enzyme immunoassay. Neutralizing antibody to human SARS-CoV also was detected in bats with lower viral loads. Precautions should be exercised in the handling of these animals.