Relationship between rate of infection and markers of inflammation/ immunity in Holy Birman cats with feline coronavirus S. Paltrinieri *, G. Rossi, A. Giordano Department of Veterinary Sciences and Public Health, University of Milan, Via Celoria 10, 20133, Milan, Italy A R T I C L E I N F O Article history: Received 17 March 2014 Accepted 26 August 2014 Keywords: Feline coronavirus (FCoV) Holy Birman cat Feline infectious peritonitis (FIP) α1-acid glycoprotein (AGP) CD4/CD8 ratio Th1 cytokines A B S T R A C T The aim of this study was to assess whether Holy Birman cats (HB) have a peculiar immune profile and a higher rate of infection by feline coronaviruses (FCoV). Leucocyte and lymphocyte subsets, antibody titers, α1-acid glycoprotein (AGP), globulin fractions, IL-4, IL-12 and IFN-γ in blood and fecal FCoV ex- cretion were determined in HB (n = 75) and in cats from other breeds (n = 94). Significantly higher CD4/ CD8 ratio, IFN-γ concentration and IL12/IL4 ratio and significantly lower IL-4 concentration and proportion of shedders were found in HB than in other breeds. No other differences were found. In conclusion, this study did not provide evidence of peculiar immune profiles in HB, except for a prevalent Th1 profile, that may explain why in our caseload the rate of shedders was lower in HB than in other breeds. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Feline infectious peritonitis (FIP) is a lethal disease caused by the feline coronavirus (FCoV). FCoVs are widely diffused in feline popu- lations, in which they usually infect enterocytes and replicate only at the intestinal level. The FCoV genome is highly unstable and rep- lication errors frequently occur. As a consequence, every cat sheds a population of heterogenous “quasispecies” (Gunn-Moore et al., 1999), characterized by a high adaptability (Domingo et al., 1996): various studies have shown that FCoV genetic heterogeneity cor- relates with the spread of the infection in the population and with the severity of clinical forms (Battilani et al., 2003; Kiss et al., 2000). The latter occur when the enteric biotype (feline enteric coronavirus or FECV) mutates into strains able to replicate within monocytes, thus inducing FIP (Vennema et al., 1998). However, the pathogen- esis of the disease in the presence of mutations is not completely understood. Currently, two theories about the role of mutated FCoVs exists: the “internal mutation theory” and the “circulating virulent/ avirulent theory” (Barker et al., 2013). According to this latter theory, both virulent and avirulent biotypes may circulate in a cattery and the disease occurs when mutated viruses infect susceptible cats (Brown et al., 2009). In addition, Dewerchin et al. (2005) showed that the ability of the host monocyte determined the amount of virus replication, no matter whether the virus was virulent or avirulent. The development of FIP in FCoV-infected cats depends also on the immune responses of the cat: a weak cell mediated (Th1) immu- nity, eventually associated with a strong humoral (Th2) immunity characterized by an overproduction of antibodies that induce a type III hypersensitivity reaction, leads to the appearance of clinical forms, while a strong cell-mediated immunity seems to be involved in re- sistance to FIP (Pedersen, 1987). As further support of the protective role of immunity, FIP occurs frequently in young and old cats, that have a less efficient immune system (Pedersen, 2009). Moreover, the comparison of results from FCoV-infected, clinically healthy cats and from cats with FIP showed some differences regarding indica- tors of innate or cell-mediated immunity, such as lymphocyte subsets, that decrease in blood and lymph nodes in FIP cats but not in FCoV-positive cats (Kipar et al., 1999, 2001; Paltrinieri et al., 2003), α1-acid glycoprotein (AGP), that increases and is hyposialylated in FIP cats (Ceciliani et al., 2004; Duthie et al., 1997), possibly de- pressing neutrophil functions (Rossi et al., 2013) and transiently increases and is hypersialylated in FCoV-positive cats (Giordano et al., 2004; Paltrinieri et al., 2007), and proinflammatory cytokines or interferon-γ (IFN-γ) whose expression and serum concentration de- creases in FIP cats and increases in FCoV-positive cats (Gelain et al., 2006; Giordano and Paltrinieri, 2009; Gunn-Moore et al., 1998; Kiss et al., 2004). Moreover, following incubation with protein N peptides derived from the sequence of FCoVs from healthy cats or from cats with FIP, feline blood cells respectively increase or decrease the production of IFN-γ (Rossi et al., 2011). From this description it is clear that the immune response plays a role in FCoV–host interaction. Genetic factors can influence the efficiency of immune responses, and a genetic predisposition to * Corresponding author. Department of Veterinary Sciences and Public Health, University of Milan, Via Celoria 10, 20133 Milan, Italy. Tel.: +02 50318103; fax: +03 50318095. E-mail address: