To evaluate the effect of UV germicidal irradiation of the air on the incidence of upper respiratory tract infections (URIs) in kittens in a nursery.
4- to 8-week-old kittens admitted to a kitten nursery in 2016 and 2018.
2 UV germicidal irradiation systems (1 within the heating, ventilation, and air conditioning system and 1 attached to the ceiling) were installed in a kitten nursery. Data were collected on the number of kittens in which a URI was diagnosed by means of a physical examination. The incidence of URIs was compared between 2016, when no UV systems were used, and 2018, when the UV systems were used.
The overall incidence of URIs in 2016 was 12.4 cases/100 kitten admissions and in 2018 was 1.6 cases/100 kitten admissions, a significant decrease of 87.1% between the years.
CONCLUSIONS AND CLINICAL RELEVANCE
A significant reduction in the incidence of URIs in kittens in a nursery was noted when the UV germicidal irradiation systems were used. Therefore, airborne transmission of feline respiratory pathogens may be more important than has been previously recognized. Ultraviolet germicidal irradiation systems that disinfect the air may be an effective adjunct to standard infection prevention and control protocols in reducing the risk of the transmission of respiratory pathogens among kittens in nurseries and shelters. However, additional studies are needed to confirm the findings reported here.
Objective—To evaluate the ability of small interfering RNAs (siRNAs) to inhibit in vitro viral replication and gene expression of feline coronavirus (FCoV).
Sample—Cell cultures of Crandell-Rees feline kidney cells.
Procedures—5 synthetic siRNAs that each targeted a different region of the FCoV genome were tested individually and in various combinations for their antiviral effects against 2 strains of FCoV (feline infectious peritonitis virus WSU 79-1146 and feline enteric coronavirus WSU 79-1683) in cell cultures. Tested combinations targeted the FCoV leader and 3′ untranslated region, FCoV leader region and nucleocapsid gene, and FCoV leader region, 3′ untranslated region, and nucleocapsid gene. For each test condition, assessments included relative quantification of the inhibition of intracellular viral genomic RNA synthesis by means of real-time, reverse-transcription PCR analysis; flow cytometric evaluation of the reduction of viral protein expression in infected cells; and assessment of virus replication inhibition via titration of extracellular virus with a TCID50 infectivity assay.
Results—The 5 siRNAs had variable inhibitory effects on FCoV when used singly. Combinations of siRNAs that targeted different regions of the viral genome resulted in more effective viral inhibition than did individual siRNAs that targeted a single gene. The tested siRNA combinations resulted in approximately 95% reduction in viral replication (based on virus titration results), compared with findings in negative control, nontargeting siRNA–treated, FCoV-infected cells.
Conclusions and Clinical Relevance—In vitro replication of FCoV was specifically inhibited by siRNAs that targeted coding and noncoding regions of the viral genome, suggesting a potential therapeutic application of RNA interference in treatment of feline infectious peritonitis.
Objective—To determine whether expression of feline coronavirus (FCoV) 7b protein, as indicated by the presence of specific serum antibodies, consistently correlated with occurrence of feline infectious peritonitis (FIP) in cats.
Sample Population—95 serum samples submitted for various diagnostic assays and 20 samples from specific-pathogen–free cats tested as negative control samples.
Procedures—The 7b gene from a virulent strain of FCoV was cloned into a protein expression vector. The resultant recombinant protein was produced and used in antibody detection assays via western blot analysis of serum samples. Results were compared with those of an immunofluorescence assay (IFA) for FCoV-specific antibody and correlated with health status.
Results—Healthy IFA-seronegative cats were seronegative for antibodies against the 7b protein. Some healthy cats with detectable FCoV-specific antibodies as determined via IFA were seronegative for antibodies against the 7b protein. Serum from cats with FIP had antibodies against the 7b protein, including cats with negative results via conventional IFA. However, some healthy cats, as well as cats with conditions other than FIP that were seropositive to FCoV via IFA, were also seropositive for the 7b protein.
Conclusions and Clinical Relevance—Expression of the 7b protein, as indicated by detection of antibodies against the protein, was found in most FCoV-infected cats. Seropositivity for this protein was not specific for the FCoV virulent biotype or a diagnosis of FIP.
To determine whether exposure to UV germicidal irradiation (UVGI) reduces concentrations of viable aerosolized microorganisms (attenuated strains of common veterinary pathogens) in a simulated heating, ventilation, and air conditioning (HVAC) system.
42 air samples seeded with bacteriophage MS2 or attenuated strains of Bordetella bronchiseptica, feline calicivirus, feline herpesvirus-1, canine parvovirus, or canine distemper virus (6/microorganism) or with no microorganisms added (6).
A simulated HVAC unit was built that included a nebulizer to aerosolize microorganisms suspended in phosphate-buffered water, a fan to produce airflow, 2 UVGI bulb systems, and an impinger for air sampling. Ten-minute trials (3 with UVGI, 3 without UVGI, and 1 negative control) were conducted for each microorganism. Impingers collected microorganisms into phosphate-buffered water for subsequent quantification with culture-based assays. Results for samples yielding no target microorganisms were recorded as the assay's lower limit of detection. Statistical analysis was not performed.
The UVGI treatment resulted in subjectively lower concentrations of viable MS2, B bronchiseptica, and canine distemper virus (arithmetic mean ± SD log10 microorganism reduction, 2.57 ± 0.47, ≥ 3.45 ± 0.24, and ≥ 1.50 ± 0.25, respectively) collected from air. Feline herpesvirus-1 was detected in only 1 sample without and no samples with UVGI treatment. Feline calicivirus and canine parvovirus were not detectable in any collected samples.
CONCLUSIONS AND CLINICAL RELEVANCE
Results for some surrogates of veterinary pathogens suggested a potential benefit to supplementing manual disinfection practices with UVGI-based air cleaning systems in animal care environments. Further research is needed to investigate the utility of UVGI in operating HVAC systems.
Objective—To analyze the 7a7b genes of the feline coronavirus (FCoV) of cheetahs, which are believed to play a role in virulence of this virus.
Sample Population—Biologic samples collected during a 4-year period from 5 cheetahs at the same institution and at 1 time point from 4 cheetahs at different institutions.
Procedures—Samples were first screened for FCoV via a reverse transcription-PCR procedure involving primers that encompassed the 3′-untranslated region. Samples that yielded positive assay results were analyzed by use of primers that targeted the 7a7b open reading frames. The nucleotide sequences of the 7a7b amplification products were determined and analyzed.
Results—In most isolates, substantial deletional mutations in the 7a gene were detected that would result in aberrant or no expression of the 7a product because of altered reading frames. Although the 7b gene was also found to contain mutations, these were primarily point mutations resulting in minor amino acid changes. The coronavirus associated with 1 cheetah with feline infectious peritonitis had intact 7a and 7b genes.
Conclusions and Clinical Relevance—The data suggest that mutations arise readily in the 7a region and may remain stable in FCoV of cheetahs. In contrast, an intact 7b gene may be necessary for in vivo virus infection and replication. Persistent infection with FCoV in a cheetah population results in continued virus circulation and may lead to a quasispecies of virus variants.
Objective—To measure antibody titers against
bovine coronavirus (BCV), determine frequency of
BCV in nasal swab specimens, and compare calves
treated for bovine respiratory tract disease (BRD)
between those given an intranasally administered
vaccine and control calves.
Design—Randomized clinical trial.
Animals—414 heifer calves.
Procedure—Intranasal BCV antigen concentration
and antibody titer against BCV were measured on
entry to a feedlot. Calves were randomly assigned to
receive 3.0 mL of a modified-live virus vaccine against
bovine enteric coronavirus and rotavirus or 3.0 mL of
saline (0.9% NaCl) solution. Calves were confined to
1 of 2 pens, depending on vaccination status, for a
minimum of 17 days of observation (range, 17 to 99).
Selection of calves for treatment of BRD and scoring
for severity of disease were done by veterinarians
unaware of treatment status.
Results—Intranasal BCV (125/407 [31%]) and serum
antibody titers ≥ 20 against BCV (246/396 [62%])
were identified in calves entering the feedlot.
Vaccination was associated with significant decrease
in risk of treatment for BRD; intranasal BCV on entry
to the feedlot was associated with increased risk of
treatment. Univariate analysis revealed that control
calves with intranasal BRD on entry to the feedlot and
those with antibody titer < 20 were significantly more
likely to be treated for BRD.
Conclusions and Clinical Relevance—These data
provide further evidence of an association between
BCV and respiratory tract disease in feedlot calves.
An intranasally administered vaccine appeared to
reduce risk of treatment for BRD. (J Am Vet Med