Background: The role of Toll-like receptors (TLRs) in a feline infectious peritonitis virus (FIPV) infection is not completely understood. Objectives: This study examined the expression of TLR3, TLR7, TLR9, tumor necrosis factoralpha (TNF-α), interferon (IFN)-β, and interleukin (IL)-10 upon an FIPV infection in CrandellReese feline kidney (CRFK) cells and feline monocytes. Methods: CRFK cells and monocytes from feline coronavirus (FCoV)-seronegative cats and FCoV-seropositive cats were infected with type II FIPV-79-1146. At four, 12, and 24 hours postinfection (hpi), the expression of TLR3, TLR7, TLR9, TNF-α, IFN-β, and IL-10, and the viral load were measured using reverse transcription quantitative polymerase chain reaction. Viral protein production was confirmed using immunofluorescence. Results FIPV-infected CRFK showed the upregulation of TLR9, TNF-α, and IFN-βexpression between 4 and 24 hpi. Uninfected monocytes from FCoV-seropositive cats showed lower TLR3 and TLR9 expression but higher TLR7 expression compared to uninfected monocytes from FCoV-seronegative cats. FIPV-infected monocytes from FCoV-seropositive cats downregulated TLR7 and TNF-α expression between 4 and 24 hpi, and 4 and 12 hpi, respectively. IFN-β was upregulated early in FIPV-infected monocytes from FCoV-seropositive cats, with a significant difference observed at 12 hpi compared to FCoV-seronegative cats.The viral load in the CRFK and FIPV-infected monocytes in both cohorts of cats was similar over time.ConclusionTLR7 may be the key TLR involved in evading the innate response against inhibiting TNF-α production. Distinct TLR expression profiles between FCoVseronegative and FCoV-seropositive cats were observed. The associated TLR that plays a role in the induction of IFN-β needs to be explored further.

Background: Poor disease management and irregular vector control could predispose sheltered animals to disease such as feline Bartonella infection, a vector-borne zoonotic disease primarily caused by Bartonella henselae. Objectives: This study investigated the status of Bartonella infection in cats from eight (n = 8) shelters by molecular and serological approaches, profiling the CD4:CD8 ratio and the risk factors associated with Bartonella infection in shelter cats. Methods: Bartonella deoxyribonucleic acid (DNA) was detected through polymerase chain reaction (PCR) targeting 16S-23S rRNA internal transcribed spacer gene, followed by DNA sequencing. Bartonella IgM and IgG antibody titre, CD4 and CD8 profiles were detected using indirect immunofluorescence assay and flow cytometric analysis, respectively. Results: B. henselae was detected through PCR and sequencing in 1.0% (1/101) oral swab and 2.0% (1/50) cat fleas, while another 3/50 cat fleas carried B. clarridgeiae. Only 18/101 cats were seronegative against B. henselae, whereas 30.7% (31/101) cats were positive for both IgM and IgG, 8% (18/101) cats had IgM, and 33.7% (34/101) cats had IgG antibody only. None of the eight shelters sampled had Bartonella antibody-free cats. Although abnormal CD4:CD8 ratio was observed in 48/83 seropositive cats, flea infestation was the only significant risk factor observed in this study. Conclusions The present study provides the first comparison on the Bartonella spp. antigen, antibody status and CD4:CD8 ratio among shelter cats. The high B. henselae seropositivity among shelter cats presumably due to significant flea infestation triggers an alarm of whether the infection could go undetectable and its potential transmission to humans.