Title: Feline coronavirus

{{Short description|Species of virus}}
{{Virusbox
| parent = Tegacovirus
| species = Alphacoronavirus suis
| virus = Feline coronavirus
| display_parents = 3
| subdivision_ranks = Strains
| subdivision_ref = &lt;ref&gt;{{cite web |title=ICTV 9th Report (2011) ''Coronaviridae'' |url=https://ictv.global/report_9th/RNApos/Nidovirales/Coronaviridae |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=10 January 2019 |language=en }}&lt;/ref&gt;
| subdivision =
* [[Feline coronavirus C1Je]]
* [[Feline coronavirus type I]]
* [[Feline coronavirus type II]]
* [[Feline infectious peritonitis virus WSU 79-1146]]
}}

'''Feline coronavirus''' ('''FCoV''') is a [[Positive-sense single-stranded RNA virus|positive-stranded RNA virus]] that infects [[cat]]s worldwide.&lt;ref name=&quot;taharaguchi&quot;&gt;{{cite journal |doi=10.1292/jvms.11-0577 |pmid=22673084 |title=Prevalence of Feline Coronavirus Antibodies in Japanese Domestic Cats during the Past Decade |year=2012 |last1=Taharaguchi |first1=Satoshi |last2=Soma |first2=Takehisa |last3=Hara |first3=Motonobu |journal=Journal of Veterinary Medical Science|volume=74 |issue=10 |pages=1355–8 |doi-access=free }}&lt;/ref&gt; It is a [[coronavirus]] of the species ''Alphacoronavirus suis'', which includes [[canine coronavirus]] (CCoV) and [[transmissible gastroenteritis coronavirus|porcine transmissible gastroenteritis coronavirus]] (TGEV). FCoV has two different forms: feline enteric coronavirus (FECV), which infects the [[intestines]], and feline infectious peritonitis virus (FIPV), which causes the disease [[feline infectious peritonitis]] (FIP).

Feline coronavirus is typically shed in faeces by healthy cats, and transmitted by the fecal-oral route to other cats.&lt;ref&gt;{{cite journal |doi=10.1016/j.cvsm.2004.10.011 |title=Feline infectious peritonitis |year=2005 |last1=Hartmann |first1=Katrin |journal=Veterinary Clinics of North America: Small Animal Practice |volume=35 |issue=1 |pages=39–79 |pmid=15627627|pmc=7114919 }}&lt;/ref&gt;  In environments with multiple cats, the transmission rate is much higher compared to single-cat environments.&lt;ref name=&quot;taharaguchi&quot; /&gt; The virus is insignificant until mutations cause it to be transformed from FECV to FIPV.&lt;ref name=&quot;taharaguchi&quot; /&gt; FIPV causes [[feline infectious peritonitis]], for which treatment is generally [[symptomatic treatment|symptomatic]] and [[palliative care|palliative]] only. The drug [[GS-441524]] shows promise as an antiviral treatment for FIP, but at the moment it still requires further research.&lt;ref name=&quot;pedersen&quot;&gt;{{cite journal |doi=10.1177/1098612X19825701|pmid=30755068|pmc=6435921|title=Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis. |year=2019 |last1=Pedersen |first1=NC|last2=Perron|first2=M|last3=Bannasch|first3=M|journal=Journal of Feline Medicine and Surgery|volume=21|issue=4|pages=271–281}}&lt;/ref&gt; The drug [[GC376]] is also being studied and developed.

==Prevalence==
Feline coronavirus is found in cat populations around the world. The only known exceptions are on the [[Falkland Islands]] and the [[Galapagos]], where studies found no occurrences of FCoV antibodies in cats tested.&lt;ref&gt;{{Cite journal|doi = 10.1177/1098612X11429644|title = Quarantine protects Falkland Islands (Malvinas) cats from feline coronavirus infection|year = 2012|last1 = Addie|first1 = Diane D.|last2 = McDonald|first2 = Mike|last3 = Audhuy|first3 = Stéphane|last4 = Burr|first4 = Paul|last5 = Hollins|first5 = Jonathan|last6 = Kovacic|first6 = Rémi|last7 = Lutz|first7 = Hans|last8 = Luxton|first8 = Zoe|last9 = Mazar|first9 = Shlomit|last10 = Meli|first10 = Marina L.|journal = Journal of Feline Medicine and Surgery|volume = 14|issue = 2|pages = 171–176|pmid = 22314098|s2cid = 4989860|doi-access = free|pmc = 10822488}}&lt;/ref&gt;&lt;ref&gt;{{Cite journal|doi = 10.1111/j.1939-1676.2007.0034.x|title = Infectious Diseases of Dogs and Cats on Isabela Island, Galapagos|year = 2008|last1 = Levy|first1 = J.K.|last2 = Crawford|first2 = P.C.|last3 = Lappin|first3 = M.R.|last4 = Dubovi|first4 = E.J.|last5 = Levy|first5 = M.G.|last6 = Alleman|first6 = R.|last7 = Tucker|first7 = S.J.|last8 = Clifford|first8 = E.L.|journal = Journal of Veterinary Internal Medicine|volume = 22|issue = 1|pages = 60–65|pmid = 18289290|pmc = 7166416|s2cid = 23423426|doi-access = free}}&lt;/ref&gt;

== Virology ==
[[File:Kedi koronavirüs testi.jpg|thumb|A test kit for the cats]]
=== Feline enteric coronavirus (FECV) ===
Feline enteric coronavirus is responsible for an infection of the mature gastrointestinal [[epithelial cells]]&lt;ref name=&quot;Rottier&quot;&gt;{{cite journal |doi=10.1128/JVI.79.22.14122-14130.2005 |title=Acquisition of Macrophage Tropism during the Pathogenesis of Feline Infectious Peritonitis is Determined by Mutations in the Feline Coronavirus Spike Protein |year=2005 |last1=Rottier |first1=Peter J. M. |last2=Nakamura |first2=Kazuya |last3=Schellen |first3=Pepijn |last4=Volders |first4=Haukeline |last5=Haijema |first5=Bert Jan |journal=Journal of Virology |volume=79 |issue=22 |pages=14122–30 |pmid=16254347 |pmc=1280227}}&lt;/ref&gt; (see also [[enterocyte]]s, [[brush border]], [[microvilli]], [[Intestinal villus|villi]]). This intestinal infection has few outward signs, and is usually chronic. The virus is excreted in the feces of the [[Asymptomatic carrier|healthy carrier]], and can be detected by [[polymerase chain reaction]] (PCR) of feces or by PCR testing of rectal samples.&lt;ref name=&quot;Rottier&quot; /&gt;

Cats living in groups can infect each other with different strains of the virus during visits to a communal litter tray. Some cats are resistant to the virus and can avoid infection or even becoming carriers, while others may become FECV carriers.&lt;ref name=&quot;Rottier&quot; /&gt;

===Feline infectious peritonitis virus (FIPV) and Feline infectious peritonitis===
{{main|Feline infectious peritonitis}}
The virus becomes feline infectious peritonitis virus (FIPV) when random errors occur in the virus infecting an [[enterocyte]], causing the virus to mutate from FECV to FIPV.&lt;ref name=&quot;Rottier&quot; /&gt;

In their pre-domestication natural state, cats are solitary animals and do not share space (hunting areas, rest areas, [[defecation site]]s, etc.). Domestic cats living in a group therefore have a much higher [[Epidemiology|epidemiological]] risk of mutation. After this mutation, the FCoV acquires a [[Tropism#Viruses |tropism]] for [[macrophages]], while losing intestinal tropism.&lt;ref name=&quot;Rottier&quot; /&gt;

In a large group of cats, ''n'', the epidemiological risk of mutation (E) is higher and expressed theoretically as: {{math|E {{=}} ''n''&lt;sup&gt;2&lt;/sup&gt; −''n''}}. A house hosting 2 cats therefore has risk of mutation E = 2. When 4 kittens (6 cats in total) are born into this house, the risk increases from 2 to 30 {{nowrap|(6&lt;sup&gt;2&lt;/sup&gt;−6)}}. Overcrowding increases the risk of mutation and conversion from FECV to FIPV, which constitutes a major risk factor for the development of feline infectious peritonitis (FIP) cases. FIP has been shown to develop in cats whose immunity is low; such as younger kittens, old cats, immunosuppression due to viral—FIV ([[feline immunodeficiency virus]]) and/or FeLV ([[feline leukemia virus]]) and stress, including the stress of separation and adoption.&lt;ref name=&quot;Rottier&quot; /&gt;

Infection of [[macrophage]]s by FIPV is responsible for development of a fatal granulomatous [[vasculitis]], or FIP (see [[granuloma]]).&lt;ref name=&quot;Rottier&quot;/&gt;  Development of FIP depends on two factors: virus mutation ''and'' low immunity where virus mutation depends on the rate of mutation of FECV to FIPV and the immune status depends on the age, the genetic pool and the stress level. High immune status will be more effective at slowing down the virus.&lt;ref name=&quot;Rottier&quot; /&gt;

== Molecular biology ==
[[File:609465.fig.001.jpg|thumb|Genetic relationships between the different feline coronaviruses (FCov) and canine coronaviruses (CCoV) genotypes. Recombination at arrows.&lt;ref&gt;{{Cite journal|last=Le Poder|first=Sophie|date=2011-07-31|title=Feline and Canine Coronaviruses: Common Genetic and Pathobiological Features|journal=Advances in Virology|volume=2011|article-number=609465|doi=10.1155/2011/609465|pmid=22312347|pmc=3265309|language=en|doi-access=free}}&lt;/ref&gt; ]]
Two forms of feline coronavirus are found in nature: enteric (FECV) and FIP (FIPV). There are also two different [[serotypes]] found with different antigens that produce unique antibodies. FCoV serotype I (also called type I) is the most frequent. Type I, that can be defined as 'FECV that could mutate to FIPV type I', is responsible for 80% of the infections. Typically, serotype I FCoV cultures are difficult to perform, with few resulting studies. FCoV serotype II (also called type II) is less frequent and is described as 'FECV type II that can mutate to FIPV type II.' FCoV type II is a recombinant virus type I with spike genes (S protein) replacement from FCoV by the [[canine coronavirus]] (CCoV) spikes.&lt;ref&gt;{{cite journal |last1=Herrewegh |first1=Arnold A. P. M. |last2=Smeenk |first2=Ingrid |last3=Horzinek |first3=Marian C. |last4=Rottier |first4=Peter J. M. |last5=De Groot |first5=Raoul J. |title=Feline Coronavirus Type II Strains 79-1683 and 79-1146 Originate from a Double Recombination between Feline Coronavirus Type I and Canine Coronavirus |journal=Journal of Virology |volume=72 |issue=5 |pages=4508–14 |date=May 1998 |pmid=9557750 |pmc=109693 |doi=10.1128/JVI.72.5.4508-4514.1998 }}&lt;/ref&gt;

More recent research points to a common ancestor between FCoV and CCoV. This ancestor gradually evolved into FCoV I. An S protein from a yet-unknown virus was passed into the ancestor and gave rise to CCoV, whose S protein was again recombined into FCoV I to form FCoV II. CCoV gradually evolved into TGEV.&lt;ref&gt;{{cite journal |last1=Jaimes |first1=Javier A. |last2=Millet |first2=Jean K. |last3=Stout |first3=Alison E. |last4=André |first4=Nicole M. |last5=Whittaker |first5=Gary R. |title=A Tale of Two Viruses: The Distinct Spike Glycoproteins of Feline Coronaviruses |journal=Viruses |date=10 January 2020 |volume=12 |issue=1 |page=83 |doi=10.3390/v12010083|pmid=31936749 |pmc=7019228 |doi-access=free }}&lt;/ref&gt;

=== FCoV type II ===

==== Virus fusion ====
Coronaviruses are covered with several types of &quot;S proteins&quot; (or E2) forming a crown of protein spikes on the surface of the virus. Coronaviruses take their name from the observation of this crown by electron microscopy. These spikes of Cov (group 1 and serotype II) are responsible for the infection power of the virus by binding the virus particle to a membrane receptor of the host cell—the Feline Amino [[peptidase]] N (fAPN).&lt;ref&gt;{{cite book |doi=10.1007/978-1-4615-5331-1_9 |pmid=9782266 |chapter=Feline Aminopeptidase N is a Receptor for All Group I Coronaviruses |title=The Effects of Noise on Aquatic Life |series=Advances in Experimental Medicine and Biology |year=1998 |last1=Tresnan |first1=Dina B. |last2=Holmes |first2=Kathryn V. |isbn=978-1-4419-7310-8 |volume=730 |pages=69–75 |editor1-first=Luis |editor1-last=Enjuanes |editor2-first=Stuart G. |editor2-last=Siddell |editor3-first=Willy |editor3-last=Spaan}}&lt;/ref&gt;&lt;ref&gt;{{cite journal |last1=Tresnan |first1=Dina B. |last2=Levis |first2=Robin |last3=Holmes |first3=Kathryn V. |title=Feline aminopeptidase N serves as a receptor for feline, canine, porcine, and human coronaviruses in serogroup I |journal=Journal of Virology |volume=70 |issue=12 |pages=8669–74 |date=December 1996 |pmid=8970993 |pmc=190961 |doi=10.1128/JVI.70.12.8669-8674.1996 }}&lt;/ref&gt;&lt;ref&gt;{{cite book |doi=10.1007/978-1-4899-1828-4_20 |pmid=9192004 |chapter=Virus-Receptor Interactions in the Enteric Tract |title=Mechanisms in the Pathogenesis of Enteric Diseases |series=Advances in Experimental Medicine and Biology |year=1997 |last1=Holmes |first1=K. V. |last2=Tresnan |first2=D. B. |last3=Zelus |first3=B. D. |isbn=978-1-4899-1830-7 |volume=412 |pages=125–33 |editor1-first=Prem S. |editor1-last=Paul |editor2-first=David H. |editor2-last=Francis |editor3-first=David A. |editor3-last=Benfield}}&lt;/ref&gt;

==== The viral receptor: aminopeptidase N (APN) ====
fAPN (feline), h[[Alanine aminopeptidase|APN]] (human) and pAPN (porcine) differ in some areas of N-[[glycosylation]]. All strains of the coronavirus study group 1 (feline, porcine and human) can bind to the feline aminopeptidase N fapn but the human coronavirus can bind to the human APN (HAPN) but not to the porcine type receptor (pAPN) and the pig coronavirus can bind to the porcine APN (pAPN) but not the human type receptor (hAPN). At the cellular level the glycosylation level of enterocytes APN is important for the binding of virus to the receptor.&lt;ref&gt;{{cite journal |doi=10.1128/JVI.75.20.9741-9752.2001 |title=Molecular Determinants of Species Specificity in the Coronavirus Receptor Aminopeptidase N (CD13): Influence of N-Linked Glycosylation |year=2001 |last1=Wentworth |first1=D. E. |last2=Holmes |first2=K. V. |journal=Journal of Virology |volume=75 |issue=20 |pages=9741–52 |pmid=11559807 |pmc=114546}}&lt;/ref&gt;&lt;ref name=&quot;Schwegmann-Wessels C, Herrler G 2008 319–29&quot;&gt;{{cite book |doi=10.1007/978-1-59745-181-9_22 |pmid=19057868 |chapter=Identification of Sugar Residues Involved in the Binding of TGEV to Porcine Brush Border Membranes |title=SARS- and Other Coronaviruses |journal=&lt;!--Bypass Citation bot --&gt; |series=Methods in Molecular Biology |year=2008 |last1=Schwegmann-Wessels |first1=Christel |last2=Herrler |first2=Georg |isbn=978-1-58829-867-6 |volume=454 |pages=[https://archive.org/details/sarsothercoronav00dave/page/319 319–29] |pmc=7122611 |editor1-first=Dave |editor1-last=Cavanagh |chapter-url-access=registration |chapter-url=https://archive.org/details/sarsothercoronav00dave/page/319 }}&lt;/ref&gt;

==== Viral spikes ====
The FECV spikes have a high affinity for [[enterocytes]] fAPN, while the mutant FIPV spikes have a high affinity for the [[macrophages]] fAPN. During the [[viral replication]] cycle, spikes proteins mature in the host cell [[Golgi complex]] with a high [[mannose]] [[glycosylation]]. This spike manno-glycosylation stage is vital for the acquisition of coronavirus virility.&lt;ref name=&quot;Rottier&quot; /&gt;&lt;ref&gt;{{cite journal |doi=10.1128/JVI.01094-08 |title=Utilization of DC-SIGN for Entry of Feline Coronaviruses into Host Cells |year=2008 |last1=Regan |first1=A. D. |last2=Whittaker |first2=G. R. |journal=Journal of Virology |volume=82 |issue=23 |pages=11992–6 |pmid=18799586 |pmc=2583691}}&lt;/ref&gt;

=== Molecular model of FCoV type I ===

==== The receptor ====
In 2007, it was well established that serotype I did not work with the FCoV fAPN receptor. The FCoV type I receptor still is unknown.&lt;ref&gt;{{cite journal |doi=10.1099/vir.0.82666-0 |title=Type I feline coronavirus spike glycoprotein fails to recognize aminopeptidase N as a functional receptor on feline cell lines |year=2007 |last1=Dye |first1=C. |last2=Temperton |first2=N. |last3=Siddell |first3=S. G. |journal=Journal of General Virology |volume=88 |issue=6 |pages=1753–60 |pmid=17485536 |pmc=2584236}}&lt;/ref&gt;

==== CoV receptors ====
The human CoV [[SARS]] binds to the [[angiotensin-converting enzyme]] ACE II. The ACE II is also called '''L-SIGN''' (liver/lymph node-specific intracellular adhesion molecules-3 grabbing non-integrin). Coronaviruses bind to macrophages via the '''D'''endritic '''C'''ell-'''S'''pecific '''I'''ntercellular adhesion molecule-3-'''G'''rabbing '''N'''on-integrin (DC-SIGN) which is a trans-membrane protein encoded in humans by the ''CD209'' gene.&lt;ref name=&quot;pmid1518869&quot;&gt;{{cite journal |doi=10.1073/pnas.89.17.8356 |title=Sequence and expression of a membrane-associated C-type lectin that exhibits CD4-independent binding of human immunodeficiency virus envelope glycoprotein gp120 |year=1992 |last1=Curtis |first1=Benson M. |last2=Scharnowske |first2=Sonya |last3=Watson |first3=Andrew J. |journal=Proceedings of the National Academy of Sciences |volume=89 |issue=17 |pages=8356–60 |jstor=2361356 |bibcode=1992PNAS...89.8356C |pmid=1518869 |pmc=49917|doi-access=free }}&lt;/ref&gt; ACE and DC-SIGN are two trans-membrane retrovirus receptors (mannose receptors) which can bind &quot;the plant lectins [[mannose receptor|C-type mannose binding domain]]&quot;.&lt;ref&gt;{{cite book |doi=10.1007/978-1-59745-393-6_4 |pmid=17502670 |chapter=The C Type Lectins DC-SIGN and L-SIGN |title=Glycovirology Protocols |journal=&lt;!--Bypass Citation bot --&gt; |series=Methods in Molecular Biology |year=2007 |last1=Lozach |first1=Pierre-Yves |last2=Burleigh |first2=Laura |last3=Staropoli |first3=Isabelle |last4=Amara |first4=Ali |isbn=978-1-58829-590-3 |volume=379 |pages=51–68|pmc=7122727 }}&lt;/ref&gt;

Aminopeptidase N has the same ability to interact with plant lectins C-type mannose-binding and also serves as a receptor for a retrovirus. Angiotensin-converting enzyme ACE, aminopeptidase A and aminopeptidase N have cascading actions in the renin-angiotensin-aldosterone system, which suggests a common [[phylogenetic]] origin between these molecules. Some advanced studies have shown a high homology between the Aminopeptidase N and the Angiotensin-converting enzyme.&lt;ref&gt;{{cite book |id={{INIST|163816}} |last1=Armelle |first1=Armelle |last2=Ascher |first2=P. |last3=Roques |first3=B.-P. |year=1993 |title=Analyse structurale du site actif de trois métallopeptidases à zinc: Endopeptidase Neutre-24. II, Aminopeptidase N et Enzyme de Conversion de l'Angiotensine |trans-title=Structural analysis of the active site of three Zinc-metallopeptidases: Neutral Endopeptidase-24.11, Aminopeptidase N and Angiotensin Converting Enzyme |language=fr |type=PhD Thesis |location=Paris |publisher=Université de Paris |oclc=490188569 |page=160}}&lt;/ref&gt;

=== Interactions between the viruses and sialic acid ===
Extensive data also shows that processes using sialic acid are directly involved in the interaction with the receptor's lectins.&lt;ref&gt;{{cite journal |doi=10.1007/s00018-005-5589-y |title=Sialic acid-specific lectins: Occurrence, specificity and function |year=2006 |last1=Lehmann |first1=F. |last2=Tiralongo |first2=E. |last3=Tiralongo |first3=J. |journal=Cellular and Molecular Life Sciences |volume=63 |issue=12 |pages=1331–54 |pmid=16596337|pmc=7079783 }}&lt;/ref&gt; It has also been demonstrated that swine enteric coronavirus (group 1) fusion to the enterocyte is accomplished via binding to the APN in the presence of the sialic acid.&lt;ref name=&quot;Schwegmann-Wessels C, Herrler G 2008 319–29&quot;/&gt;&lt;ref&gt;{{cite journal |doi=10.1128/JVI.76.12.6037-6043.2002 |title=Binding of Transmissible Gastroenteritis Coronavirus to Cell Surface Sialoglycoproteins |year=2002 |last1=Schwegmann-Wessels |first1=C. |last2=Zimmer |first2=G. |last3=Laude |first3=H. |last4=Enjuanes |first4=L. |last5=Herrler |first5=G. |journal=Journal of Virology |volume=76 |issue=12 |pages=6037–43 |pmid=12021336 |pmc=136196}}&lt;/ref&gt;&lt;ref&gt;{{cite journal |doi=10.1128/JVI.77.21.11846-11848.2003 |title=Binding of Transmissible Gastroenteritis Coronavirus to Brush Border Membrane Sialoglycoproteins |year=2003 |last1=Schwegmann-Wessels |first1=C. |last2=Zimmer |first2=G. |last3=Schröder |first3=B. |last4=Breves |first4=G. |last5=Herrler |first5=G. |journal=Journal of Virology |volume=77 |issue=21 |pages=11846–8 |pmid=14557669 |pmc=229351}}&lt;/ref&gt; Feline coronavirus infections are therefore sialic acid dependent.&lt;ref&gt;{{cite journal |doi=10.1016/j.jfms.2008.04.004 |title=Association between faecal shedding of feline coronavirus and serum α1-acid glycoprotein sialylation |year=2008 |last1=Paltrinieri |first1=Saverio |last2=Gelain |first2=Maria E. |last3=Ceciliani |first3=Fabrizio |last4=Ribera |first4=Alba M. |last5=Battilani |first5=Mara |journal=Journal of Feline Medicine &amp; Surgery |volume=10 |issue=5 |pages=514–8 |pmid=18701332|pmc=7129531 |doi-access=free }}&lt;/ref&gt;&lt;ref&gt;{{cite journal |doi=10.1016/j.jfms.2007.01.002 |title=Serum α1-acid glycoprotein (AGP) concentration in non-symptomatic cats with feline coronavirus (FCoV) infection |year=2007 |last1=Paltrinieri |first1=S |last2=Metzger |first2=C |last3=Battilani |first3=M |last4=Pocacqua |first4=V |last5=Gelain |first5=M |last6=Giordano |first6=A |journal=Journal of Feline Medicine &amp; Surgery |volume=9 |issue=4 |pages=271–7 |pmid=17344083|pmc=7129318 |doi-access=free }}&lt;/ref&gt;

The [[Porcine epidemic diarrhea virus]] (PEDV) S protein is 45% identical to FCoV type I spike. An EM structure of it shows sialic acid binding sites. The PEDV receptor is also unknown.&lt;ref&gt;{{cite journal |last1=Wrapp |first1=Daniel |last2=McLellan |first2=Jason S. |last3=Gallagher |first3=Tom |title=The 3.1-Angstrom Cryo-electron Microscopy Structure of the Porcine Epidemic Diarrhea Virus Spike Protein in the Prefusion Conformation |journal=Journal of Virology |date=13 November 2019 |volume=93 |issue=23 |doi=10.1128/JVI.00923-19|pmid=31534041 |pmc=6854500 }}&lt;/ref&gt;
&lt;!--
===Inhibition of the fusion: some studies (in vitro)===
To inhibit the fusion of the virus to the cell, several solutions are possible:
# modify glycosylation level of the viral spikes,
# Change the level of glycosylation of fAPN,
# Compete with the spikes, with molecules that will bind to fapn (occupation of the binding site),
# Inhibit the binding depends on the sialic acid mucus.
* Experimentally the binding of FIPV (spike) in macrophages (fapn) is strongly inhibited by [[mannan]](s)''( [[mannose]] complex sugar&amp;nbsp;— see also, [[glycan]], manno-oligosaccharide, MOS [[oligosaccharide]])'': that compete with the fapn. With mannose, the inhibition is less than with Mannan-oligosaccharides.
* Some Molecules can inhibit glycosylation of spikes (monensin, tunicamycin ...) reduce or cancel the virus infesting power (action in the Golgi. The same is true for mannanases and mannosidase enzymes that cut mannose out of the spikes.
* The competition with spikes by other molecules having an affinity for fapn'' '(common sugar recognition process)''' cancel or reduce the power of infesting CoV:

'''- Mannan binding [[Lectin]]:'''
** '''''plant Lectin'''''&lt;ref&gt;{{cite journal |pmc=7114093 |  doi=10.1016/j.antiviral.2007.03.003 |title=Plant lectins are potent inhibitors of coronaviruses by interfering with two targets in the viral replication cycle |year=2007 |last1=Keyaerts |first1=Els |last2=Vijgen |first2=Leen |last3=Pannecouque |first3=Christophe |last4=Van Damme |first4=Els |last5=Peumans |first5=Willy |last6=Egberink |first6=Herman |last7=Balzarini |first7=Jan |last8=Van Ranst |first8=Marc |journal=Antiviral Research |volume=75 |issue=3 |pages=179–87 |pmid=17428553}}&lt;/ref&gt;

# [[Allium]] agglutinins
# [[Urtica dioica]] agglutinins
# Pradamycine A .../...
** '''''humoral lectin'''''
# [[Ficoline]]
# [[Collectine]] .../...

'''-Manno-[[Oligosaccharides]] (MOS) :''' source: yeast

'''- [[sialic acid]] :'''

Experimental sialic acid inhibition can decrease the avian and human coronavirus infectivity.&lt;ref&gt;{{cite journal |pmc=7110564|  doi=10.1016/j.micinf.2007.12.009 |title=Infection of the tracheal epithelium by infectious bronchitis virus is sialic acid dependent |year=2008 |last1=Winter |first1=Christine |last2=Herrler |first2=Georg |last3=Neumann |first3=Ulrich |journal=Microbes and Infection |volume=10 |issue=4 |pages=367–73 |pmid=18396435}}&lt;/ref&gt;
--&gt;
&lt;!-- Is this really a necessary component of this page? --&gt;

== Effects of breast milk on kittens ==
=== Colostrum ===
Other molecules from [[colostrum]] and cat milk, could also bear this coverage: [[lactoferrin]], [[lactoperoxidase]], [[lysozyme]], rich [[proline]] polypeptide — PRP and alpha-[[lactalbumine]]. Lactoferrin has many properties that make it a very good candidate for this anti-coronavirus activity:
# For FCoV group II, it binds to APN.&lt;ref&gt;{{cite journal |vauthors=Ziere GJ, Kruijt JK, Bijsterbosch MK, Berkel TJ |title=Recognition of lactoferrin and aminopeptidase M-modified lactoferrin by the liver: involvement of the remnant receptor |journal=Zeitschrift für Gastroenterologie |volume=34 |issue=3 |pages=118–21 |date=June 1996 |pmid=8767485}}&lt;/ref&gt;
# For SARS CoV, it binds to ACEs&lt;ref&gt;{{cite journal |doi=10.1021/jf060482j |title=Lactoferricin-Related Peptides with Inhibitory Effects on ACE-Dependent Vasoconstriction |year=2006 |last1=Centeno |first1=José M. |last2=Burguete |first2=María C. |last3=Castelló-Ruiz |first3=María |last4=Enrique |first4=María |last5=Vallés |first5=Salvador |last6=Salom |first6=Juan B. |last7=Torregrosa |first7=Germán |last8=Marcos |first8=José F. |last9=Alborch |first9=Enrique |last10=Manzanares |first10=Paloma |journal=Journal of Agricultural and Food Chemistry |volume=54 |issue=15 |pages=5323–9 |pmid=16848512}}&lt;/ref&gt;
# It also binds to [[DC-SIGN]] of macrophages,&lt;ref&gt;{{cite journal |doi=10.1128/JVI.79.5.3009-3015.2005 |title=Lactoferrin Prevents Dendritic Cell-Mediated Human Immunodeficiency Virus Type 1 Transmission by Blocking the DC-SIGN--gp120 Interaction |year=2005 |last1=Groot |first1=F. |last2=Geijtenbeek |first2=T. B. H. |last3=Sanders |first3=R. W. |last4=Baldwin |first4=C. E. |last5=Sanchez-Hernandez |first5=M. |last6=Floris |first6=R. |last7=Van Kooyk |first7=Y. |last8=De Jong |first8=E. C. |last9=Berkhout |first9=B. |journal=Journal of Virology |volume=79 |issue=5 |pages=3009–15 |pmid=15709021 |pmc=548463 }}&lt;/ref&gt;
# The lactoferrin anti-viral activity is sialic-acid–dependent.

The structures of the [[polypeptide chain]] and carbohydrate moieties of [[bovine lactoferrin]] (bLF) are well established. bLF consists of a 689-[[amino acid]] polypeptide chain to which complex and high-[[mannose]]-type [[glycan]]s are linked.&lt;ref&gt;{{cite journal |doi=10.1111/j.1432-1033.1991.tb15801.x |title=Molecular cloning and sequence analysis of bovine lactotransferrin |year=1991 |last1=Pierce |first1=Annick |last2=Colavizza |first2=Didier |last3=Benaissa |first3=Monique |last4=Maes |first4=Pierrette |last5=Tartar |first5=Andre |last6=Montreuil |first6=Jean |last7=Spik |first7=Genevieve |journal=European Journal of Biochemistry |volume=196 |pages=177–84 |pmid=2001696 |issue=1|doi-access=free }}&lt;/ref&gt;

=== Other components ===
The [[colostrum]] and breast milk also contain:

# Many [[oligosaccharide]]s ([[glycan]]) which are known for their anti-viral properties which is thought to be primarily due to their inhibition of pathogen binding to host cell ligands.&lt;ref&gt;{{cite journal |doi=10.1146/annurev.nutr.25.050304.092553 |title=Human Milk Glycans Protect Infants Against Enteric Pathogens |year=2005 |last1=Newburg |first1=David S. |last2=Ruiz-Palacios |first2=Guillermo M. |last3=Morrow |first3=Ardythe L. |journal=Annual Review of Nutrition |volume=25 |pages=37–58 |pmid=16011458}}&lt;/ref&gt;
# Many maternal immune cells.
# Many [[cytokines]] ([[interferon]], etc.), whose role by oro-mucosal route seems very important.&lt;ref&gt;{{cite journal |vauthors=Dec M, Puchalski A |title=Use of oromucosally administered interferon-alpha in the prevention and treatment of animal diseases |journal=Polish Journal of Veterinary Sciences |volume=11 |issue=2 |pages=175–86 |year=2008 |pmid=18683548}}&lt;/ref&gt;&lt;ref&gt;{{cite journal |last=Tovey |first=Michael G. |title=Special Oromucosal Cytokine Therapy : Mechanism(s) of Action |journal= The Korean Journal of Hepatology |volume=8 |issue=2 |pages=125–31 |date=June 2002 |pmid=12499797 |url=http://www.e-cmh.org/journal/view.php?year=2002&amp;vol=8&amp;no=2&amp;spage=125}}&lt;/ref&gt;&lt;ref&gt;{{cite journal |doi=10.1089/10799900152547830 |title=Oromucosal Interferon Therapy: Relationship Between Antiviral Activity and Viral Load |year=2001 |last1=Schellekens |first1=Huub |last2=Geelen |first2=Gerard |last3=Meritet |first3=Jean-François |last4=Maury |first4=Chantal |last5=Tovey |first5=Michael G. |journal=Journal of Interferon &amp; Cytokine Research |volume=21 |issue=8 |pages=575–81 |pmid=11559435}}&lt;/ref&gt;
# Sialic acid: during lactation, neutralizing oligo-saccharides binding sialic acid decreases when it binds increasingly to glycoproteins.&lt;ref&gt;{{cite journal |doi=10.3168/jds.S0022-0302(01)74558-4 |title=Distribution of Bovine Milk Sialoglycoconjugates During Lactation |year=2001 |last1=Martín |first1=M.-J. |last2=Martín-Sosa |first2=S. |last3=García-Pardo |first3=L.-A. |last4=Hueso |first4=P. |journal=Journal of Dairy Science |volume=84 |issue=5 |pages=995–1000 |pmid=11384055|doi-access=free }}&lt;/ref&gt; (The APN is a glycoprotein.) The anti-viral effect of lactoferrin is increased by the removal of sialic acid.&lt;ref&gt;{{cite journal |doi=10.1016/S0304-4165(01)00178-7 |title=Involvement of bovine lactoferrin metal saturation, sialic acid and protein fragments in the inhibition of rotavirus infection |year=2001 |last1=Superti |first1=Fabiana |last2=Siciliano |first2=Rosa |last3=Rega |first3=Barbara |last4=Giansanti |first4=Francesco |last5=Valenti |first5=Piera |last6=Antonini |first6=Giovanni |journal=Biochimica et Biophysica Acta (BBA) - General Subjects |volume=1528 |issue=2–3 |pages=107–15 |pmid=11687297|hdl=11573/83235 |hdl-access=free }}&lt;/ref&gt;
# Mannan-binding lectins.&lt;ref&gt;{{cite journal |doi=10.1002/jcla.10055 |title=Changes in the mannan binding lectin (MBL) concentration in human milk during lactation |year=2002 |last1=Trégoat |first1=Virginie |last2=Montagne |first2=Paul |last3=Béné |first3=Marie-Christine |last4=Faure |first4=Gilbert |journal=Journal of Clinical Laboratory Analysis |volume=16 |issue=6 |pages=304–7 |pmid=12424804|pmc=6807810 }}&lt;/ref&gt;

=== Other protective factors ===
Other assumptions may help to explain this resistance to FCoV infections by kittens. In the first weeks of life, APN could be immature because highly manno-glycosylated.&lt;ref&gt;{{cite journal |doi=10.1016/0016-5085(95)90561-8 |title=Localization and biosynthesis of aminopeptidase N in pig fetal small intestine |year=1995 |last1=Danielsen |first1=E.Michael |last2=Hansen |first2=Gert H. |last3=Niels-Christiansen |first3=Lise-Lotte |journal=Gastroenterology |volume=109 |issue=4 |pages=1039–50 |pmid=7557068}}&lt;/ref&gt; The spikes of CoV could then not be bound. Factors in breastmilk may inhibit the synthesis of fANP by enterocytes, as already described with fructose or sucrose.&lt;ref&gt;{{cite journal |doi=10.1021/bi00123a008 |title=Folding of intestinal brush border enzymes. Evidence that high-mannose glycosylation is an essential early event |year=1992 |last1=Danielsen |first1=E. Michael |journal=Biochemistry |volume=31 |issue=8 |pages=2266–72 |pmid=1347233}}&lt;/ref&gt;&lt;ref&gt;{{cite journal |last1=Danielsen |first1=E. Michael |last2=Hansen |first2=Gert H. |last3=Wetterberg |first3=Lise-Lotte |title=Morphological and functional changes in the enterocyte induced by fructose |journal=The Biochemical Journal |volume=280 |issue=2 |pages=483–9 |date=December 1991 |pmid=1684104 |pmc=1130574 |doi=10.1042/bj2800483 }}&lt;/ref&gt;&lt;ref&gt;{{cite journal |last=Danielsen |first=E. Michael |title=Post-translational suppression of expression of intestinal brush border enzymes by fructose |journal=The Journal of Biological Chemistry |volume=264 |issue=23 |pages=13726–9 |date=August 1989 |doi=10.1016/S0021-9258(18)80059-X |pmid=2569463 |url=http://www.jbc.org/cgi/pmidlookup?view=long&amp;pmid=2569463|doi-access=free }}&lt;/ref&gt;

== See also ==
* [[Alphacoronavirus_1|Alphacoronavirus 1]] 

==References==
{{Reflist|colwidth=30em}}

==External links==
* [http://www.dr-addie.com Dr ADDIE website focused research about FIP]
* [https://web.archive.org/web/20090515172705/http://www.microbiologybytes.com/virology/Coronaviruses.html Coronavirus Site général]
* [http://virologie.free.fr/documents/virologie/34-Coronaviridae/coronaviridae.htm Coronavirus site général]
* [http://www.virology.net/Big_Virology/BVRNAcorona.html Coronavirus Pictures] {{Webarchive|url=https://web.archive.org/web/20210211030719/http://www.virology.net/Big_Virology/BVRNAcorona.html |date=2021-02-11 }}

{{Coronaviridae}}
{{Domestic cat}}
{{Taxonbar|from=Q454829}}

[[Category:Animal viral diseases]]
[[Category:Cat diseases]]
[[Category:Alphacoronaviruses]]
[[Category:Infraspecific virus taxa]]