Researchers investigated the stability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among bodily fluids observed in animals in a recent study published in the journal Viruses.
SARS-CoV-2 has consistently changed genetically, overcame species barriers, and increased its host range since its discovery in 2019. Furthermore, new research has discovered interspecies transmission, such as infection of domestic pets and viral circulation among wildlife. However, because previous investigations focused mostly on human biological fluids, understanding SARS-CoV-2 stability within animal biological fluids and their role in viral transmission is restricted.
Concerning the research
Kansas State University researchers investigated SARS-CoV-2 stability in biological fluids taken from three animal species, namely sheep, cats, and white-tailed deer, in the current study. (WTD).
Salivary, fecal, and urine samples were taken from sheep, cats, and WTDs. Four days after SARS-CoV-2 injection, cytopathological effects were examined, followed by viral titer measurement. SARS-CoV-2 variants of concern (VOCs) were tested for stability in WTD fecal suspensions using SARS-CoV-2 Alpha, Delta, and Omicron VOCs grown in Vero-transmembrane serine protease 2 (TMPRSS2) cells. Each viral stock was also sequenced. The WA-1 strain was grown in Vero-TMPRSS2 cells to produce virus inocula under similar conditions. The researchers calculated the SARS-CoV-2 viral decay rate by assessing whether the related specimens were virus positive for at least two time points.
The researchers discovered that after incubating SARS-CoV-2 in cat biological fluids, they found low infectious virus levels ranging from 100.767 to 101.633 TCID50 isolated for up to one day post-contamination (dpc) within pooled cat saliva samples, regardless of environmental conditions. At one-hour post-contamination (hpc), pooled cat feces specimens indicated viral titers ranging from 100.767 to 102.412 TCID50, but active virus could not be found at 7 hpc.
SARS-CoV-2 persisted for up to one day in the pooled cat 10% fecal suspension in winter and indoor conditions, with half-life values of 9.16 hours and 5.99 hours, respectively. The team, on the other hand, discovered longer virus survival in cat urine samples. In addition, in pooled alone with two individual cat urine specimens, SARS-CoV-2 demonstrated stability for up to three to seven days in fall or spring settings. Notably, for all three tests of cat urine specimens, the half-life values observed for winter conditions were much less than those observed for fall or spring settings.
The stability of SARS-CoV-2 in pooled cat saliva (A), pooled cat feces (B), pooled cat 10% fecal suspension (C), pooled sheep saliva (D), pooled white-tailed deer saliva (E), and pooled white-tailed deer feces (F) was investigated. (F). Each biological fluid was spiked with 5 104 TCID50 of SARS-CoV-2 and incubated inside (gray), in the summer (red), in the spring/fall (green), and in the winter (blue). The virus was recovered and titrated on Vero E6 cells at each time point. When the infectious virus was present at two separate time points, the simple linear regression was computed. The virus titer is depicted as the mean and standard deviation of log-transformed TCID50 titers (colored circle), whereas negatives in triplicate are represented by empty colored circles. The colored lines and their shaded areas reflect the simple linear regression’s best-fit line and 95% confidence range. 0.04 and 0.29 days on the x-axis correspond to 1 and 7 hours, respectively. The virus’s stability was observed at two-time intervals due to an insufficient volume of pooled sheep saliva (D). Because the slope of simple linear regression was not statistically different from zero in pooled cat saliva under spring/fall and winter settings (A) and pooled white-tailed deer feces under summer conditions (F), the best-fit line was not shown.
After incubating the virus in sheep biological fluids, a viral titer of 102.301 TCID50 was recovered at 1 hpc in pooled sheep saliva samples in an indoor environment, whereas no virus was discovered under summer conditions. Furthermore, SARS-CoV-2 exhibited stability for up to 1 dpc within pooled sheep saliva samples, with half-life values of 9.04 hours and 7.34 hours, respectively, in spring/fall and winter settings. Despite this, no infectious virus was found from pooled sheep fecal samples or 10% fecal suspensions at any of the time points investigated.
SARS-CoV-2 survived for 1 dpc in WTD pooled saliva samples after virus incubation, demonstrating half-life values of 1.23 hours for the indoor environment, 1.08 hours for the summer environment, and 4.52 hours for the winter environment. SARS-CoV-2 exhibited excellent stability in pooled WTD fecal samples for up to 6 dpc, with a half-life of 6.28 hours in indoor conditions, six hours in fall/spring environments, and 24.44 hours in winter environments. This conclusion was clearly in contrast to the findings for fecal samples from sheep, cats, and people.
SARS-CoV-2 was likewise stable in WTD pooled urinary samples for up to 21 dpc, with a seasonal stability tendency. However, a urine sample collected from the bladder of one WTD during necroscopy revealed that SARS-CoV-2 was only stable for up to 7 hpc in summer and indoor environments and 1 dpc in winter and fall/spring environments. This demonstrated that viral decay rates differed in urine samples taken from the same patient using different procedures.
The outcomes of the investigation revealed that SARS-CoV-2 may survive in the salivary samples of sheep, cats, and WTDs for up to one day following inoculation. The virus could be isolated in WTD fecal samples for up to six days and in WTD fecal suspensions for up to 15 days. The virus, however, was rather unstable in sheep and automobile fecal samples and suspensions. While the specific significance of biological excretions and secretions in the viral transmission is unknown, the researchers believe their findings provide new insight into their role in SARS-CoV-2 transmission.