《1993 Coronavirus Infection in Cats》由会员分享，可在线阅读，更多相关《1993 Coronavirus Infection in Cats（16页珍藏版）》请在金锄头文库上搜索。
1、FELINE INFECTIOUS DISEASES 0195-5616193 $o.oo + .2u CORONA VIRUS INFECTION IN CATS Johnny D. Hoskins, DVM, PhD Coronavirus infections are significant in the worlds cat population.1 2 As many as 80% to 90% of cats are affected within individual catteries and multicat households. 2 Cats are susceptibl
2、e to infection with several different strains of feline corona virus. 2 3 Depending on the involved strain, clinical signs may range from asymptomatic infection _to gastrointestinal disease of varying severity to widespread fibrinous serositis and disseminated vasculitis, commonly known as feline in
3、fectious peritonitis (FIP).2 CORONA VIRUSES Coronaviruses are spherical, enveloped viruses that average 100 nm in diameter, possessing a single-stranded nonsegmented RNA genome of positive polarity. The virus particle is composed of structural proteins: nucleocapsid protein and spike glycoproteins.1
4、9 35 The nucleocapsid protein occurs in the core of the virus and is composed of only polypeptides. The spike glycoproteins are associated with the envelope of the virus.35 The spike glycoproteins occur as petal-shaped projections, or peplomers, that extend outward from the envelope of the virus;13
5、these proteins are associated with attachment of the coronavirus to receptor sites on susceptible cells. Peplomers also may be major inducers of protective immunity in an infected host. After ingestion or inhalation of a coronavirus, younger members of the host species tend to develop signs of infec
6、tion, whereas the asymptomatic carrier state is more common in adult animals. Replication of coronaviruses occurs at the cytoplasmic membranes, as the virus buds into vacuoles within cell cytoplasm. 36 Corona virus remains cell-associated throughout the course of infection and is released after the
7、cell is destroyed. Replication of virus is rapid; cycle is complete in less than 24 hours.36 From the Department of Veterinary Clinical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana VETERINARY CLINICS OF NORTH AMERICA: SMALL ANIMAL PRACTICE VOLUME 23 NUMB
8、ER 1 JANUARY 1993 1 2 HOSKINS In many species of animals, coronaviruses have a relatively restricted organ tropism. They infect the respiratory or gastrointestinal system, or both.41 FIP coronavirus, feline enteric coronavirus, canine coronavirus (CCV), transmissible gastroenteritis virus (TGEV) of
9、swine, and human respiratory tract coronavirus comprise an antigenic cluster of closely related viruses within the family Coronaviridae.34 The major structural proteins of these coronaviruses are antigenically similar to the extent that most investigators consider these coro- naviruses as host-range
10、 variants rather than individual corona virus species. 5 Strains of feline coronavirus that infect cats have been divided into those that cause FIP and those that induce subclinical to severe enteritis (Table 1). 30 Strains of FIP coronavirus differ from those of feline enteric coronavirus in that F
11、IP coronavirus is able to escape from the gastrointestinal tract and spread to replication sites in other organs. Strains of FIP coronavirus and feline enteric coronavirus probably represent pathogenic variants of a single coronavirus type. Alternatively, strains of FIP coronavirus may arise as muta
12、nts of feline enteric coronavirus strains.33 Current knowledge of the cell culture-adapted strains of feline coronavirus is based on their morphologic, structural, and antigenic relationship to TGEV and CCV; the nature of the disease caused in the host; growth characteristics in cell culture systems
13、; and the degree of relatedness to CCV in virus neutralization tests.30 FIP Coronavirus The most virulent strains of FIP coronavirus, such as FIPV-79-1146 and FIPV-DF2, cause fatal FIP disease in most cats inoculated oronasally, whereas strains of intermediate virulence, such as FIPV-UCDl, cause FIP
14、 disease in cats undergoing extended exposure. Strains of low virulence, such as FIPV-UCD2 and FIPV-UCD3, can become established as asymptomatic infections; fatal FIP disease occurs only if the immunologic responsiveness of the host later becomes compromised. 33 Most cases of FIP disease result from
15、 infection with strains similar to FIPV- TN406 and not with those strains of FIP coronavirus that are closely related to CCV.33 Most asymptomatic cats with positive coronavirus-antibody titers have been previously infected by strains of feline enteric coronavirus or FIP corona- virus, which usually
16、do not cause fatal disease by natural routes of infection. Asymptomatic cats, however, may later succumb if exposed to a more virulent strain of FIP coronavirus. Coronavirus antibody-positive cats that resist later challenge probably seroconvert as a result of a systemic infection with a virulent strain of FIP corona virus. 25 Table 1. IDENTIFIED STRAINS OF FELINE CORONA VIRUS Strains that induce FIP disease FIPV-79-1146 FIPV-UCD1 FIPV-UCD2 FIPV-UCD3 FIPV-UCD4 FIPV-TN406 (Black)
