Clinical relationship of FCoV/FIPV infections

Transcription

1 Clinical relationship of FCoV/FIPV infections Assoc. Professor Parnchitt Nilkumhang KVAC 2015 One Health Workforces : Best Practices in Thailand Venue: Centara and Convention Center Hotel,Khonkaen, July 24 th 2015

2 FIP is difficult to diagnose and treated. FIP diagnosis and treatment are frustrated to well communication?

3 Diagnosis of FIP :A frustation Clinical Examination and environmental consideration Laboratory supports Imaging findings Cytology, Serology and molecular diagnosis Histopathological confirmation

4 What is the PROBLEM of FIP diagnosis Sick cats presented with no effusion (pleural /peritoneal cavity) dry FIP Normal/healthy shedder cats

5 Physical and Environmental findings Multifactoral risk Owner Multi-cat household Cat Age,blood line Pure breeds > DSH Immune response Virus Mutation Uncertain period (exposed to clinically sick) Environment Stress Physical findings Depend on when the cats are presented Early Mid Late

6 How does AGE of sick cat help the diagnosis? Inc period 2-14 days (exp l) FCoV in feces found as early as 2 days after exposure (main site is colon) Clinical FIP found as early as 2 wk old to 18 months and elderly > 12 yr From pyogranulomatous inflammation to clinical signs may be many months

7 How does AGE of sick cat help the diagnosis? Pattern of virus nature Pathogenesis of virulent/non virulent virus Exposure time to clinical sickness Factors of immune response Concurrent diseases Inc period 2-14 days (exp l) FCoV in feces found as early as 2 days after exposure (main site is colon) Clinical FIP found as early as 2 wk old to 18 months and elderly > 12 yr From pyogranulomatous inflammation to clinical signs may be many months

8 เรามาถ งจ ดน ได อย างไร

9 Objective: Knowing FCoVs

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11 Clinical relationship of FCoVs,FECV and FIPV

12 Feline coronavirus classification flowchart. A. Kipar, and M. L. Meli Vet Pathol 2014;51: Copyright by American College of Veterinary Pathologists

13 Feline coronavirus classification flowchart. A. Kipar, and M. L. Meli Vet Pathol 2014;51: Copyright by American College of Veterinary Pathologists

14 CCoV, FCoV, TGEV All group 1 Coronavirus are antigenically related FCoV is divided into 2 serotypes FCoV 1 FCoV 2 FCoV 2 is antigenically similar to CCoV ( FCoV 2 is a recombinant of FCoV and CCoV) BUT most field-strains are FCoV 1

15 Genetic relationships between the different feline and canine coronaviruses genotypes (FCoV, CCoV and TGEV). From

16 FCoVs who are they? FCoV I 2 serotypes FCoV II

17 FCoVs who are they? FCoV I 2 serotypes FECV FCoV II 2 biotypes/ pathotypes Enteric biotype Virulent biotype FIPV FECV,FIPV -serological/morphological undistinguishable

18 Prevalence of Feline Coronaviruses (FCoV) Housed cats % of cats infected with FCoV Multi cat household/ colonies % of cats infected with FCoV In high prevalent area, occurrence of FIP ~ 10%

19 How FECV turn into FIPV Two theories Internal mutation Circulating virulent / avirulent viruses FIPV and FECV strains can be serotpye I or II

20 Mutation: when FECV turns into FIPV Internal mutation theory Genetic changes from FECV to FIPV in individual infected cat Various types of mutation within 3c gene 20% of kittens infected with FECV will produce an FIP mutant.

21 Molecular Studies for diagnosis of FIP Conflicting results FCoV 1 (FIPV I) virulent? FCoV II (FIPV II) non-virulent?

22 Pathogenesis of FIP: controversial?? Immune-mediated vasculitis Immune complex Type 3 hypersensitivity disease Ag + Ab +compliments +C3 Pathological morphology Activation of monocytes/ macrophages Monocyte-mediated viremia Granulomatous phleblitis /periphlebitis VEGF mediators increase vascular permeability

23 Endothelial cells show strongly MHCII antigen positive. Activated macrophages A. Kipar et al. Vet Pathol 2005;42: Copyright by American College of Veterinary Pathologists

24 Morphologic Features and Development of Granulomatous vasculitis in FIP : Kipar et al(2005)

25 Emigration of FCoV infected monocytes to vascular /perivascular granulomatous infiltrates with destruction of vascular basal laminar Leptomeningeal veins. Agglomerate of TNF-α-positive monocytes attached to venous endothelium. Avidin-biotin-peroxidase complex method. Papanicolaou's hematoxylin counterstain. Bar = 10 μm A. Kipar et al. Vet Pathol 2005;42: Copyright by American College of Veterinary Pathologists

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27 Objective: Knowing FCoVs FCoVs in clinical diagnosis

28 Serology and Molecular diagnosis Indirect: FCoV antibody test Blood Feces Effusion fluid CSF Direct (viral load): FCoV RT-PCR At present, NO nucleoprotein sequences unique to pathogenic FCoV (ie, not also present in nonpathogenic FCoV) have been identified

29 FCoV FECV FCoV : where are they? Asymptomatic or mild diarrhea Small intestinal enterocytes Healthy shedders After clearance from sm intestine, FCoVs spread to infect colon and intermittently shedded off Colon -rectum

30 If kittens infected before immune system fully mature, levels of FECV replication will be very high.

31 Reinfection may be from FCoV same strains or different strains

32 Pyogranulomatous inflammation FIPV infected monocytes /perivascular macrophages overproduce neutrophil survival factors: Tumor necrosis factoralpha (TNF alpha) Matrix metalloproyeinase-9 GM-CSF G-CSF Neutrophil survival Development of granuloma lesions

33 Interpretation of FCoV antibody test Viral shedding ~ 2 days (FCoV in epithelial cells) Signs of FIP As early as 2 wk old to 18 months From pyogranulomatous inflammation to clinical signs may be months From NC Pederson et al (2008): Feline enteric coronavirus infection

34 When is in-house FCoV antibody test required? Which test? To rule out FIP in sick cats effusive FIP non- effusive FIP ( esp cats with GI signs) To screen the FCoV excretors Cats in contact with known FCoV shedder Cats in the household New kitten or new cat bringing into the multi-cat household Before receiving immunosuppressive treatment or stressful procedures

35 When is in-house FCoV antibody test required? Which test? To screen a breeding queen To monitor FIP treatment q 8-12 wks To screen blood donor cat To screen prior to FeLV vaccination

36 Blood / fluid Interpretation of FCoV antibody test I. false negative in sick FIP cat II. High titer (> 1,1600) in normal cat (esp cat from multi-household) is not indicated FIP III. High titer in fluid, high PPV IV. Generally not recommended in sick cat

37 FCoV antibody in CSF Use of anti-coronavirus antibody testing of cerebrospinal fluid for diagnosis of feline infectious peritonitis involving the central nervous system in cats. J Am Vet Med Assoc. January 2007;230(2): Irene C Boettcher 1 ; Tanja Steinberg; Kaspar Matiasek; Craig E Greene; Katrin Hartmann; Andrea Fischer CSF IgG was detected only in strongly seropositive cats suggested that CSF anti-coronavirus IgG was derived from blood. Measurement of anti-coronavirus IgG in CSF was of equivocal clinical use.

38 Test test test

39 FCoV RT-PCR test ( blood/effusion fluid/feces) Blood FCoV RT-PCR FECV Monocyte-associated viremia? Not differentiate FIPV from pathotype FCoV Effusion fluid FCoV RT-PCR Generally recommended for fluid Positive result,high PPV But 30% of effusions from cats with FIP may be negative by RT- PCR Fecal FCoV RT-PC Recommend for house-cat management BUT single positive or negative tests are meaningless as cats may shed intermittently or may be recently infected. Why false negative 1. FIPV is cell-associated and likely confined to cells of perivascular granuloma (leaking out of pure plasma) 2. Inhibition of RT-PCR by interfering substances in fluid Therefore negative result doesn t exclude FIP

40 Is FIP a contagious disease (cat-to-cat transmission)?

41 Is FIP a contagious disease (cat-to-cat transmission)? Cats with FIP do not excrete pathogenic FIPV!!! FECV in enterocytes

42 Is FIP contagious? Cats with FIP do not appear to be very contagious to cats coming in contact with. Every FIPV isolated from a group outbreak of FIP does NOT genetically identical in its 3c gene mutation. However FIPV is found in the feces of most cats with FIP

43 Mutation: when FECV turns into FIPV Internal mutation theory Genetic changes from FECV to FIPV Various types of mutation within OPFs 3 and 7 20% of kittens infected with FECV will produce an FIP mutant. Horizontal (cat-to cat) Transmission of FIPV mutants cats with FIP are shedding the same FIPV in their feces

44 FIP transmission J Gen Virol Feb;91(Pt 2): doi: /vir Epub 2009 Nov 4. Feline infectious peritonitis: insights into feline coronavirus pathobiogenesis and epidemiology based on genetic analysis of the viral 3c gene. Chang HW 1, de Groot RJ, Egberink HF, Rottier PJ..Most cats with FIP had no detectable intestinal feline coronaviruses (FCoVs) and had seemingly cleared the primary FECV infection. In those with detectable intestinal FCoV, the virus always had an intact 3c and seemed to have been acquired by FECV superinfection. Apparently, 3c-inactivated viruses replicate not at all--or only poorly--in the gut, explaining the rare incidence of FIP outbreaks.

45 FIP transmission Vet Res Jul 17;44:57. doi: / An outbreak of feline infectious peritonitis in a Taiwanese shelter: epidemiologic and molecular evidence for horizontal transmission of a novel type II feline coronavirus Wang YT 1, Su BL, Hsieh LE, Chueh LL. Abstract Sequence analysis revealed that the type II FIPV detected from fecal samples, body effusions and granulomatous tissue homogenates from the cats that succumbed to FIP all harbored an identical recombination site in their S gene. Two of the cats that succumbed to FIP were found to harbor an identical nonsense mutation in the 3c gene. Fecal shedding of this type II virus in the effusive form of FIP can be detected up to six days before death. Taken together, our data demonstrate that horizontal transmission of FIPV is possible and that FIP cats can pose a potential risk to other cats living in the same environment.

46 FCoV field strain in FIP cat Genomic RNA sequence of feline coronavirus strain FCoV C1Je Charlotte Dye, BVM&S, PhD, CertSAM, MRCVS Stuart G. Siddell, BSc(Hons), PhD This paper reports the first genomic RNA sequence of a field strain feline coronavirus (FCoV). Viral RNAs isolated at post mortem from the jejunum and liver of a cat with feline infectious peritonitis (FIP) derived 100% nucleotide identity.

47 Feline Coronavirus serotypes I and II were reported in natural infection Feline coronavirus serotypes 1 and 2: seroprevalence and association with disease in Switzerland. Clin Diagn Lab Immunol. October 2005;12(10): Maya Kummrow 1 ; Marina L Meli; Michael Haessig; Enikoe Goenczi; Amy Poland; Niels C Pedersen; Regina Hofmann-Lehmann; Hans Lutz Comparison of serologic techniques for the detection of antibodies against feline coronaviruses. J Vet Diagn Invest. January 2008;20(1): Annamaria Pratelli 1 Prevalence of Korean cats with natural feline coronavirus infections. Virol J. January 2011;8(0):455. Dong-Jun An 1 ; Hye-Young Jeoung; Wooseog Jeong; Jee Yong Park; Myoung-Heon Lee; Bong Kyun Park. 1 National Veterinary Research and Quarantine Service, Anyang, Kyunggi-do, Korea. Mores

48 Take home message Knowing ME,knowing YOU

49 My team, my world Thank you