Co-circulation of two SARS-CoV-2 variant strains within imported pet hamsters in Hong Kong

Abstract

During the investigation of a pet shop outbreak of severe acute respiratory coronavirus 2 (SARS-CoV-2) with probable hamster-to-human transmission, the environmental and hamster samples in epidemiologically linked pet shops were found positive for SARS-CoV-2 Delta variant AY.127 strains which are phylogenetically closely related to patients and reported European strains. This interspecies’ spill-over has triggered transmission in 58 patients epidemiologically linked to three pet shops. Incidentally, three dwarf hamsters imported from the Netherlands and centralized in a warehouse distributing animals to pet shops were positive for SARS-CoV-2 spike variant phylogenetically related to European B.1.258 strains from March 2020. This B.1.258 strain almost disappeared in July 2021. While no hamster-to-human transmission of B.1.258-like strain was found in this outbreak, molecular docking showed that its spike receptor-binding domain (RBD) has a similar binding energy to human ACE2 compared to that of Delta variant AY.127. Therefore, the potential of this B.1.258-related spike variant for interspecies jumping cannot be ignored. The co-circulation of B.1.258-related spike variants with Delta AY.127, which originated in Europe and was not previously found in Hong Kong, suggested that hamsters in our wholesale warehouse and retail pet shops more likely have acquired these viruses in the Netherlands or stopovers during delivery by aviation than locally. The risk of human-to-hamster reverse zoonosis by multiple SARS-CoV-2 variants leading to further adaptive spike mutations with subsequent transmission back to humans cannot be underestimated as an outbreak source of COVID-19. Testing imported pet animals susceptible to SARS-CoV-2 is warranted to prevent future outbreaks.

The novel hamster-adapted SARS-CoV-2 Delta variant may be selectively advantaged in humans

“…host-driven, to improve affinity for the receptor and/or to escape immune response. This correspond to what has been described on hamsters [2,3]. However, in this case these mutations appear to be also more favorable for the virus on humans.…”

“…The same applies in the case of the hamster-adapted Delta variant recently described in Hong Kong [2,3]. On January 18, 2022, the Hong Kong sanitary authorities ordered the culling of hamsters, closed pet-shops and sent pet-shop visitors into quarantine after hamsters sold at a local store were found infected with the Delta variant of SARS-CoV-2 [2,3]. This variant initially infected an employee and a customer and further human-to-human transmission was evidenced [2,3].…”

“…We have previously reported on the importance of the structural dynamic of SARS-CoV-2 variants for risk assessment [1]. The same applies in the case of the hamster-adapted Delta variant recently described in Hong Kong [2,3]. On January 18, 2022, the Hong Kong sanitary authorities ordered the culling of hamsters, closed pet-shops and sent pet-shop visitors into quarantine after hamsters sold at a local store were found infected with the Delta variant of SARS-CoV-2 [2,3].…”

“…On January 18, 2022, the Hong Kong sanitary authorities ordered the culling of hamsters, closed pet-shops and sent pet-shop visitors into quarantine after hamsters sold at a local store were found infected with the Delta variant of SARS-CoV-2 [2,3]. This variant initially infected an employee and a customer and further human-to-human transmission was evidenced [2,3]. This is reminiscent of what happened in Denmark with the SARS-CoV-2 outbreak in farmed minks which infected humans back [4,5].…”

Spreading of SARS-CoV-2 from hamsters to humans

“…Reported separately, a second strain was found in some animals in the warehouse, showing that the infection of the hamsters was not a one-off incident. 7 This zoonotic transmission of SARS-CoV-2 from hamsters is consistent with experimental observations of efficient hamster-tohamster transmission via different routes. 8 Zoonotic transmission of viruses from pet rodents to humans has been witnessed on many occasions.…”