key: cord-0924636-iq22h3yg authors: Wendling, Natalie M.; Carpenter, Ann; Liew, Amanda; Ghai, Ria R.; Gallardo‐Romero, Nadia; Stoddard, Robyn A.; Tao, Ying; Zhang, Jing; Retchless, Adam C.; Ahmad, Ausaf; Bunkley, Paige; Godino, Claire; Mauldin, Matthew R.; Varela, Kate; Ritter, Jana M.; Hennebelle, Janemarie; Feldpausch, Amanda; Gabel, Julie; Kainulainen, Markus H.; Herzegh, Owen; Tong, Suxiang; Spengler, Jessica R.; Barton Behravesh, Casey title: Transmission of SARS‐CoV‐2 Delta variant (B.1.617.2) from a fully vaccinated human to a canine in Georgia, July 2021 date: 2022-04-14 journal: Zoonoses Public Health DOI: 10.1111/zph.12944 sha: d7028a7dda6e65442cb5b85de9b6126bf80a6d76 doc_id: 924636 cord_uid: iq22h3yg SARS‐CoV‐2 infection has been described in a wide range of species, including domestic animals such as dogs and cats. Illness in dogs is usually self‐limiting, and further diagnostics may not be pursued if clinical signs resolve or they respond to empirical treatment. As new variants emerge, the clinical presentation and role in transmission may vary in animals. This report highlights different clinical presentations and immunological responses in two SARS‐CoV‐2 Delta‐variant‐positive dogs with similar exposure to the same fully vaccinated human with a SARS‐CoV‐2 infection and emphasizes the need for active surveillance and additional One Health research on SARS‐CoV‐2 variant infections in companion animals and other species. Four swab specimens were collected from each dog at two time points (n = 16), using sterile plastic-handled, polyester-tipped applicators. Specimens were placed in 0.5 ml of viral transport media (VTM) prepared by CDC's Division of Scientific Resources according to the Standard Operating Procedure #DSR-052-05 (CDC, 2020). Following RNA extraction, all swab specimens were tested using the CDC Influenza SARS-CoV-2 (Flu SC2) Multiplex Assay (Shu et al., 2021) , a real-time reverse transcription PCR (rRT-PCR) targeting the matrix 1 (M1) gene and non-structural 2 (NS2) gene for human influenza A and B, respectively, and the nucleocapsid (N) gene for specific detection of SARS-CoV-2. Blood specimens (n = 6) were collected in 5 ml vacutainer serum separator tubes from the cephalic vein of both dogs at three time points. Serological response against SARS-CoV-2 was determined using a species-independent assay detecting antibody binding to the receptor-binding domain (RBD) of the viral spike (S) protein (Kainulainen et al., 2021) . A 2-year-old, 31.4 kg (69 lb) neutered male bulldog mix (Dog 1) residing in Georgia, USA, developed a dry, non-productive cough and lethargy on 16 July 2021. On physical exam at onset of clinical signs, Dog 1 was quiet, alert and responsive. An intermittent mild to moderate dry, non-productive cough was noted but tracheal palpation elicited no cough. No other significant findings or history of illness or comorbidities were noted. Dog 1 was prescribed prednisone (1 mg/kg PO, tapered over 10 days) and doxycycline (5 mg/kg PO BID) at onset of clinical signs, continued to exhibit intermittent dry, non-productive cough for 5 days, then recovered uneventfully. A cohoused 11-year-old, 15.6 kg (34.4 lb) neutered male French bulldog (Dog 2) was bright, alert and responsive; he appeared normal with respect to his age and known history of severe, chronic atopic dermatitis, and remained clinically normal. Three days before clinical onset in Dog 1, the owner reported having mild COVID-19 symptoms (Figure 1 After confirming SARS-CoV-2 infection in the owner and following consultation with state public and animal health officials, both dogs were tested for SARS-CoV-2 through investigations by the CDC in To investigate the viral relatedness between human and canine SARS-CoV-2 positive specimens, sequences from four specimens Calvet et al., 2021; van der Leij et al., 2021) . Here, Dog 2 was positive for SARS-CoV-2 by rRT-PCR, but antibodies were not detected. Possible explanations include a long-term history of oral oclacitinib maleate administration, mutations in the RBD altering assay sensitivity for Delta or a true absence of antibodies despite infection. Evidence of immunocompetence in Dog 2 and detection of a moderate serological response in Dog 1 suggests that immunosuppression or assay limitations are less likely and that this case may represent undetectable SARS-CoV-2 antibody titres, as reported in asymptomatic SARS-CoV-2 infections in people (Chan et al., 2020; Marchi et al., 2021) . Delta variant is associated with increased transmission rates in humans (CDC, 2021b; Li et al., 2022) ; the estimated average reproduction number (R0), or the expected number of secondary cases from one primary case in a susceptible population, is 5.1, significantly higher than early pandemic strains (estimated R0 2.79; Liu & Rocklöv, 2021) . Whether the genomic changes facilitating transmission in humans also result in increased spread within other species is unknown but as SARS-CoV-2 variants emerge in human populations, these variants are expected to be identified in animals Yaglom et al., 2021) . Klimova for assistance with editing the manuscript. The authors declare that there were no conflicts of interest. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the CDC. Complete or near-complete genome sequences of SARS-CoV-2 obtained in this investigation are available at GenBank (accession nos. OK174325, OK174326 and MZ741014). TA B L E 1 Summary of SARS-CoV-2 sequence analysis from owner and two household dogs positive for SARS-CoV-2 Delta variant (B. Abbreviations: −, indicates a deletion; --, sequence data not obtained in region indicated; Ct, cycle threshold;NA, not applicable; NR, not reported. Experimental insfection of domestic dogs and cats with SARS-CoV-2: Pathogenesis, transmission, and response to reexposure in cats Investigation of SARS-CoV-2 infection in dogs and cats of humans diagnosed with COVID-19 in Rio de Janeiro, Brazil Delta variant: what we know about the science. 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