SARS-CoV-2 Kappa Variant Shows Pathogenicity in a Syrian Hamster Model

Area of Science:

• Virology
• Pathogen research
• Infectious disease

Background:

• The SARS-CoV-2 B.1.617 lineage, including the Kappa variant (B.1.617.1), emerged during a significant surge in infections in India.
• Understanding the pathogenic potential of emerging SARS-CoV-2 variants is crucial for public health.
• Syrian golden hamsters are a relevant animal model for studying SARS-CoV-2 pathogenesis.

Purpose of the Study:

• To investigate and compare the pathogenic potential of the SARS-CoV-2 Kappa variant (B.1.617.1) against the B.1 (D614G) lineage in a hamster model.
• To assess clinical signs, viral load, and immune responses induced by each variant.

Main Methods:

• Two groups of Syrian golden hamsters were intranasally inoculated with either the B.1 or Kappa variant of SARS-CoV-2.
• Animals were monitored for clinical signs and body weight changes.
• Viral RNA load was quantified in respiratory and lung tissues using RT-qPCR.
• Histopathological analysis of lung tissues was performed.
• Neutralizing antibody titers were measured.

Main Results:

• Kappa variant-infected hamsters exhibited greater body weight loss compared to those infected with the B.1 variant.
• High viral RNA loads were detected in the nasal turbinate and lungs for both variants.
• The Kappa variant led to significantly higher subgenomic RNA (sgRNA) loads in nasal swabs, trachea, and lungs at specific time points.
• Kappa variant infection resulted in more severe lung lesions (gross and microscopic) than B.1 infection.
• While B.1-infected hamsters developed comparable neutralizing antibody responses against both variants, Kappa-infected hamsters showed lower titers against the B.1 isolate.

Conclusions:

• The SARS-CoV-2 Kappa variant demonstrates increased pathogenicity in Syrian golden hamsters, characterized by pronounced weight loss, high viral loads in the respiratory tract and lungs, and severe lung lesions.
• Both the Kappa and B.1 variants elicited neutralizing antibody responses in infected hamsters, though the cross-neutralization profile differed.
• This study highlights the distinct pathogenic characteristics of the Kappa variant in a relevant animal model.