SARS-CoV-2 Exposure in Norway Rats (Rattus norvegicus) from New York City.

Area of Science:

• Veterinary Virology
• Zoonotic Diseases
• Urban Ecology

Background:

• Millions of Norway rats inhabit New York City, posing a potential risk for SARS-CoV-2 transmission between humans and rats.
• Understanding the susceptibility of urban wildlife to SARS-CoV-2 is crucial for public health surveillance.

Purpose of the Study:

• To evaluate SARS-CoV-2 exposure in NYC Norway rats.
• To assess the susceptibility of rats to SARS-CoV-2 variants (Alpha, Delta, Omicron).
• To investigate the potential for reverse zoonotic transmission.

Main Methods:

• Serological testing (IgG/IgM) on 79 wild Norway rats captured in NYC.
• RT-qPCR and partial genome sequencing of SARS-CoV-2 from positive rat samples.
• Infection challenge study using Sprague Dawley rats with Alpha, Delta, and Omicron variants.

Main Results:

• 16.5% of wild rats tested positive for SARS-CoV-2 antibodies.
• Partial SARS-CoV-2 genomes recovered from qRT-PCR positive rats, linked to early pandemic lineage B.
• Rats are susceptible to Alpha, Delta, and Omicron variants, with high viral replication in respiratory tracts.
• The Delta variant exhibited the highest infectivity in experimental infections.

Conclusions:

• Wild Norway rats in NYC have been exposed to SARS-CoV-2.
• Rats are susceptible to infection with multiple SARS-CoV-2 variants, including Alpha, Delta, and Omicron.
• Findings underscore the need for monitoring SARS-CoV-2 in urban rat populations due to potential reverse zoonotic transmission risk to humans.