The four connected cat rooms Figure 3 were dusted daily using a broom, but no disinfection took the place of either the floor or any other material in the cat rooms, including food and water bowls. The bowls were only rinsed with soap after daily use. Obvious stains on the floor e. The cat feces and urine were removed daily from the two litter trays and if necessary new cat litter, Aspen 6 wood shavings Le Comptoir Des Sciures, Meyzieu, France , was added.
Prior to use, the cat litter was autoclaved to prevent the import of pathogens. No additional cleaning or disinfection was performed in-between the two FCV challenges. In contrast to the cat rooms, the rest of the area within the inner barrier room for clinical examination and sample collection, corridors, etc. Afterwards the excessive water was again removed with a floor squeegee and the disinfection with Incidin TM Plus Ecolab, Monheim am Rhein, Germany , containing the active agent glucoprotamin, was performed to prevent introduction of any additional pathogens from outside of the facility; glucoprotamin has only a limited virucidal effect, mostly against enveloped viruses [ 33 ].
The Incidin TM Plus Ecolab was allowed to stay on the floors for at least 15 min before removing it using water and a floor squeegee. All waste that was generated within the inner barrier area was collected in biohazard bins Mauser , sealed and removed for autoclaving to prevent FCV contamination outside the cat facility.
None of the oropharyngeal cytobrush samples tested positive after day 71 following FCV exposure. FCV positive results were obtained from all items that were either in direct or indirect contact with the cats, but not in the food storage room that was behind the inner barrier Table 2.
Remarkably, also the filter protecting the ventilation that was not in direct contact with the cats and was changed daily tested positive at many time points, but only as long as some cats were shedding FCV. The highest frequency of positive objects was found early after infection. On days 1 to 13, 6 to 8 out of 8 tested items were FCV positive Table 2. This decreased to 2 to 4 out of 8 items on days 15 to 56 and finally to 1 to 2 out of 8 on days 63 to No samples were collected between day and day , since none of the cats had been shedding as of day At that time point, all tested items were FCV-negative.
The transfer area between two rooms, the ventilation filter and the two food bowls showed the highest frequency of FCV positivity; 13 to 18 time points out 20 tested after the experimental infection were positive for FCV Table 2.
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The lowest Ct-value Ct-values below All environmental items were additionally tested for the presence of replicating virus using CRFK cell culture. The supernatant from four samples tested weakly positive: The water samples collected on days 3 and 8 Ct-values This cat had been shedding FCV until day No samples from early infection were available.
On day 3, after the second FCV challenge, four of the ten cats were shedding replicating FCV as determined in cell culture. By day 22, all cats had stopped shedding FCV Table 3. This is the first comprehensive study to investigate FCV contamination of a research cat facility following experimental infection of the cats with two FCV field strains.
This included items that were in direct contact with the cats, i. However, FCV viral RNA was also detected at the ventilation filter, which was not in direct contact with FCV-shedding cat; this finding indicated that there was the aerosol spread of the virus in environmental dust and cat hair.
Although FCV viral RNA was detected on many items, we found no or only limited evidence of FCV with replication capacity in the environment, as tested by virus isolation in cell culture. During the entire time course of the study, no FCV was detected outside the inner barrier area. These results are important to understand the potential of FCV for environmental contamination and the effect of optimal hygienic measures. Consequently, environmental contamination was found on all tested items in the cat rooms that were in direct or indirect contact with the cats.
Subsequently, a decrease in environmental contamination was observed, with fewer items testing positive for FCV RNA over time. Moreover, sampling of the environment in different places was standardized, and samples were analyzed using RT-qPCR. This decrease in environmental contamination reflected the shedding pattern of the cats.senjouin-renkai.com/wp-content/tracker/whatsapp-blaue-haken-wieder-verschwunden.php
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Accordingly, the contamination of the environment after the second FCV infection was not as extensive as after the first FCV infection. During the first infection, only one cat was shedding FCV from day 43 until day Nonetheless, environmental contamination remained detectable up to day after the first FCV infection. Therefore, we hypothesize that the persistence of FCV outside the host could also be strain-dependent. It has been shown that some FCV strains were more resistant to disinfection with different biocides than others [ 11 ], and Lee and Gillespie [ 34 ] found differences in the resistance of two different FCV strains to changes in pH.
Therefore, further studies with different FCV strains from cats with different clinical signs, including virulent-systemic isolates, will be required to confirm these findings. We stopped environmental sampling at day until day after the first infection. We can, therefore, not estimate the maximal time span during which FCV might be expected to remain in the environment.
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The solid dry surfaces food bowls, floor in the transfer area and ventilation filter showed a significantly higher frequency of FCV positivity than the water and the litter trays. This confirms data from a recent study by Buckley et al. We assume that the relative humidity for FCV on this item was variable, depending on different water levels in the bowl.
Even though FCV is mainly shed via the oral route, there are reports of isolation of FCVs from feline urine [ 36 , 37 , 38 ]. Limited shedding in urine could account for the limited contamination of the litter tray. On the other hand, FCV shed by the cats could have been absorbed by the litter, which was not tested in this study. In a recent study, it was shown that the type of litter used could influence the environmental spread of FCoV via cat feces and litter boxes [ 39 ].
Moreover, the sampling method and the presence of substances, i. During the study, the idea arose to also test the cat hair of infected cats for the persistence of FCV. However, cat JJH3 had stopped shedding FCV after day 71, which could at least partially explain why no more hair samples tested FCV-positive, despite cats regularly licking their hair during grooming. Following the second FCV infection, we collected hair samples early during infection at day 9. Although FCV viral RNA was found in abundance in the environment, no replication competent virus was detected using virus isolation; only minimal RT-qPCR signals were found in four of the cell culture supernatants.
It has been reported that the number of viral genomes detected, and the presence of infectious viruses do not necessarily correlate [ 40 ]. The viral capsid could have been damaged by environmental influences resulting in replication incompetent virions that were nonetheless still detectable by molecular methods [ 40 , 41 ]. This could have also been the case in our study. However, it might also be that the viral loads in this study were too low to initiate efficient virus replication in cell culture; this does not exclude the possibility that the loads might have been sufficient to infect a cat directly.
Even so, our findings seem to contrast with current literature. Clay et al. However, the latter two studies on FCV stability in the environment used a different approach to that used here; first, the contamination of fomites occurred artificially and second, the FCV laboratory strain F9 was used. The laboratory strain FCV F9 has been used for many years for laboratory and vaccine studies, and therefore, has been propagated in cell culture numerous times.
Prolonged culturing of FCV can influence the composition of the virus quasispecies [ 34 ]. Radford et al.
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Additionally, virus neutralization tests showed that FCV isolates directly obtained from cats evolved antigenically over the course of an infection, whereas, isolates passaged in cell culture no longer showed changes in their neutralization pattern [ 35 ]. The FCV field strains tested in this study were derived from Swiss domestic pet cats presented to veterinarians with oral ulcerations, gingivitis, stomatitis, fever and depression.
The two field strains showed low sequence identity between each other and towards FCV F9, indicating that they are all separate FCV strains [ 1 ]. The two field FCV strains were passaged and expanded in cell culture only four to five times before inoculation of the SPF cats in the present study.
We suggest that artificial contamination is not comparable with natural contamination via shedding by FCV-infected cats in terms of viral loads and distribution of the contaminant. In particular, the distribution of the contaminant is a challenge for the sampling method in a natural setting. In contrast, in an artificial setting, it is known precisely where the pathogen was placed, and samples can be collected from that location.
We tested those places we expected to be contaminated, since each cat had to interact with those places or items on a daily basis. However, in the present study, only a small fraction of the entire possibly contaminated area could be sampled, which could explain the lack of recovery of replicating viruses. The ten cats in this study had a total of We assume that this is more surface space per cat than what isusually provided for cats in clinical environments and rescue shelters.
Furthermore, we assume that the sampling method might influence the number of viral particles recovered. Three different methods for the recovery of FCV were compared on wool and nylon carpets in a study by Buckley et al. On these surfaces, especially, macrofoam-tipped swabbing revealed very low recovery efficiency compared to the bottle extraction and the microbial vacuum method [ 35 ].
Although we also used swabbing in our study, we sampled only firm surfaces with cotton swabs.