Viral loads of SARS-CoV-2 RNA determined by real-time PCR in animals in the study of experimental infection and transmission of SARS-CoV-2 Delta and Omicron variants among beagle dogs.  A) Viral loads in nasal swab samples from infected dogs.  B) Viral loads in nasal swab specimens from naive (transmission) dogs exposed to dogs infected with Delta or Omicron variants.  NC, normal control;  DI, delta variant infection;  OI, omicron variant infection;  DT, delta variant transmission;  OT, omicron variant transmission.

Experimental an infection and transmission of SARS-CoV-2 Delta and Omicron variants amongst Beagle canines

Writer Affiliations: Jeonbuk Nationwide College, Iksan, South Korea (KS. Lyoo, S.-G. Lee); Seoul Nationwide College, Seoul, South Korea (H. Lee, M. Yeom, D. Tune); Korean Company for Illness Management and Prevention, Cheongju, South Korea (J.-Y. Lee, Ok.-C. Kim, J.-S. Yang)

Since COVID-19 was first reported in China in late 2019 and quickly grew to become a worldwide pandemic, the zoonotic facets of SARS-CoV-2 have raised public well being issues (1). The primary reported case of SARS-CoV-2 an infection in a pet was in Hong Kong (2). Companion canines dwelling with COVID-19 sufferers shed low ranges of SARS-CoV-2 and present seroconversion with none medical indicators (2). Since then, a number of circumstances of SARS-CoV-2 transmission from people to canines have been reported in a number of nations (3). In experimental an infection research, canines inoculated with the wild pressure SARS-CoV-2 exhibited no medical indicators or seroconversion, misplaced low titres, or had undetectable viral RNA.4,5). As companion animals, canines generally share dwelling areas with people; subsequently, additional research are wanted to make clear the susceptibility of canines to SARS-CoV-2 an infection.

SARS-CoV-2 variants Delta, in late 2020, and Omicron, in 2021, have emerged and unfold quickly world wide. These variants had been characterised by extra environment friendly human-to-human transmission than the wild-type pressure.6). On this examine, we evaluated the susceptibility of beagle canines to SARS-CoV-2 Delta and Omicron variants and the transmissibility of SARS-CoV-2 variants from contaminated canines to naïve canines.

We obtained the Omicron (NCCP 43408, BA.1.) and Delta (NCCP 43390, B.1.617.2) SARS-CoV-2 variants from the Nationwide Tradition Assortment for Pathogens of South Korea. We double-passed viruses into Vero E6 cells and titrated virus shares on Vero E6 cells utilizing 50% tissue tradition infectious dose (TCID50) sensible. This examine was performed on the Animal Use Biosafety Degree 3 facility of the Korea Zoonosis Analysis Institute. The Institutional Animal Care and Use Committee has accepted animal experiments (Approval Quantity JBNU 2022033), and the Institutional Biosafety Committee of Jeonbuk Nationwide College has accepted experimental protocols requiring biosafety (Approval Quantity JBNU202202002).

We bought 9 male beagle canines, all 9 months previous, from Orient Bio Inc. ( We intranasally inoculated 2 canines with 106.0 TCID50/mL SARS-CoV-2 Delta variant and a pair of others with 106.0 TCID50/mL SARS-CoV-2 Omicron variant (contaminated canines). Twenty-four hours after an infection, we housed 2 virus-naïve canines (transmission canines) every with contaminated canines in separate massive animal isolators, 1 for Delta-infected canines and 1 for Omicron-infected canines (complete 4 canines in every isolator, 2 contaminated and a pair of naïve). We assigned 1 naïve canine as an uninfected unfavorable management and saved him separate from different canines. We recorded physique temperature and weight, and picked up blood, nasal swabs, and rectal swabs on day and a pair of, 4, 6, 8, and 10 days after an infection for contaminated canines or days after beginning cohousing for canines of transmission. All canines had been humanely killed 10 days after an infection or cohousing, after which we collected lung tissue for histopathological examination and measurement of viral load.

Utilizing an Exigo C200 computerized analyzer (Boule Medical AB,, we examined complete protein, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine kinase, creatinine, urea nitrogen, urea nitrogen / creatinine and glucose. All outcomes had been inside reference ranges besides creatine kinase which, 4 days after an infection or cohousing, was practically 8 occasions the higher restrict of regular vary (0200 U/L) in 1 contaminated canine (OI-1, 1,589 U/L) and 1 transmission canine (OT-1, 1,560 U/L) with Omicron variant (determine within the appendix). In the course of the examine, not one of the canines confirmed any medical indicators of sickness, together with weight reduction or fever.

Determine 1

Determine 1. Viral a great deal of SARS-CoV-2 RNA decided by real-time PCR in animals within the examine of experimental an infection and transmission of SARS-CoV-2 Delta and Omicron variants amongst beagle canines. A) Viral load…

To measure viral RNA a great deal of SARS-CoV-2 in lung tissue and swab samples, we used real-time quantitative PCR to detect the nucleocapsid gene of SARS-CoV-2 utilizing TaqMan Quick Virus 1-Step Grasp Combine (Thermo Fisher Scientific,, as described elsewhere (7,8). We cultured virus from all nasal swab samples utilizing a TCID50 check with Vero E6 cells. We didn’t detect viral RNA in lung tissue or rectal swab specimens. Nevertheless, nasal swab samples taken from all canines 2 days after an infection with the Delta or Omicron variants had been constructive for SARS-CoV-2 RNA; we additionally detected viral RNA in swab samples taken from Delta-infected canines 4 days after an infection (Determine 1, panel A). Within the SARS-CoV-2 transmission portion of the examine, we detected viral RNA in nasal swab samples taken 2 days after transmission from canines within the Delta and Omicron variant transmission teams; Viral RNA hundreds from the two canines within the Delta variant group (4.4 and 4.9 log10 genome/buffer copies) had been better than 2 within the Omicron variant group (1.2 and 1.3 log10 genome/buffer copies) (Determine 1, panel B). Viral shedding from contaminated canines and transmission was revealed by cultivation of the virus (Desk).

determine 2

Pathological changes in lungs of dogs in the study of experimental infection and transmission of SARS-CoV-2 variants Delta and Omicron among beagle dogs.  A) Lung tissue from a dog experimentally infected with the Delta variant shows strongly thickened alveolar septa from infiltrating lymphocytes, macrophages, degenerated neutrophils, and karyorrhetic cellular debris.  B) Lung tissue from a naive (transmission) dog hosted by a Delta-infected dog shows thickened alveolar septa from infiltration of numerous macrophages and lymphocytes, along with collagen accumulation.  C) Lung tissue from a dog experimentally infected with the Omicron variant shows severe interstitial pneumonitis and thickening of the alveolar septum due to infiltration of degenerated lymphocytes, macrophages, and neutrophils.  D) Lung tissue from a naive (transmission) dog housed with an Omicron-infected dog shows thickened alveolar septa from a few macrophages, lymphocytes, and degenerated neutrophils.  Original magnification 400.

Determine 2. Pathological modifications in lungs of canines within the examine of experimental an infection and transmission of SARS-CoV-2 Delta and Omicron variants amongst beagle canines. A) Lung tissue from experimentally contaminated canine…

In the course of the post-mortem on the finish of the experiment, we discovered no gross lesions in any organs, however each contaminated and transmission canines confirmed histopathological modifications within the lungs. The alveolar wall was regionally thickened by infiltration of lymphocytes and monocytes, together with macrophages, and by proliferation of the alveolar epithelium (Determine 2).

The continued emergence of variant SARS-CoV-2 strains poses a risk to public well being and challenges the efficacy of present vaccines. Delta and Omicron variants are extra transmissible and immune to neutralization than different strains in vaccinated folks (6). Though the SARS-CoV-2 pandemic has been pushed primarily by human-to-human transmission, zoonotic viral an infection from companion animals to people has been reported incessantly worldwide.3). To look at this dynamic, experimental an infection research had been performed utilizing totally different animal species, together with canines (3,5).

For this examine, we intranasally contaminated 9-month-old beagle canines with SARS-CoV-2 Delta and Omicron variants; our outcomes display that the canines had been vulnerable to an infection and will transmit each strains to different canines by means of direct contact. Regardless of the absence of medical indicators, microscopic lesions had been noticed within the lungs of each contaminated and transmitting canines. Amongst blood chemistry parameters, creatine kinase ranges had been markedly elevated in Omicron-infected canines. Creatine kinase is a marker of muscle injury, and excessive ranges, comparable to these discovered amongst Omicron-infected canines, are related to worse outcomes in respiratory sufferers contaminated with influenza viruses or SARS-CoV-2 (9,10). Nevertheless, we couldn’t rule out the chance that creatine kinase might be elevated by muscle damage induced in an uncontrolled state of affairs comparable to a canine battle as a substitute of SARS-CoV-2 an infection. Due to this fact, additional research to elucidate the position of blood chemistry parameters, comparable to creatine kinase, in animal fashions could be worthwhile.

The upper infectivity of the SARS-CoV-2 variants in comparison with the wild-type viral pressure led us to carry out this experimental examine of an infection and transmission in canines. Human-shedding variants of SARS-CoV-2 might successfully infect and flow into amongst companion animals, comparable to canines or cats.11,12). It has been hypothesized that these companion animals might later zoonotically infect people. This state of affairs raises issues about potential spillover between people and companion animals, which can require ongoing surveillance to trace SARS-CoV-2 variants in companion animals. Sooner or later, profitable vaccination methods for companion animals might be efficient as a public well being intervention to guard animals from an infection and forestall zoonotic transmission from contaminated animals.

Dr. Lyoo is Deputy Director of Analysis at Jeonbuk Nationwide College. His analysis pursuits embody the pathogenesis of animal viruses and vaccine improvement.


Leave a Reply

Your email address will not be published. Required fields are marked *