《2011 Detection and genetic characterization of canine parvoviruses and coronaviruses in southern Ireland》由会员分享，可在线阅读，更多相关《2011 Detection and genetic characterization of canine parvoviruses and coronaviruses in southern Ireland（9页珍藏版）》请在金锄头文库上搜索。
1、BRIEF REPORT Detection and genetic characterization of canine parvoviruses and coronaviruses in southern Ireland Susan McElligottP. J. CollinsRoy D. Sleator Vito MartellaNicola DecaroCanio Buonavoglia Helen OShea Received: 27 May 2010/Accepted: 8 November 2010/Published online: 24 November 2010 ? Sp
2、ringer-Verlag 2010 AbstractCanine parvovirus (CPV) and canine corona- virus (CCoV) are considered the main pathogens respon- sible for acute gastroenteritis in dogs. From a collection of 250 samples, seven CPV strains and three CCoV strains were identifi ed in symptomatic Irish dogs. Samples were sc
3、reened for the viruses using polymerase chain reaction (PCR) and typed via DNA sequence analysis. Three CPV strains were characterized as CPV-2a, while four others were characterized as CPV-2b. To date, CPV-2c remains unreported in Ireland. Two CCoV strains were character- ized as CCoV-II and one as
4、 CCoV-I. In the case of one sample, PH4/09/Ire, a mixed infection with CPV and CCoV was detected. Canine parvovirus type 2 (CPV) and canine coronavirus (CCoV) are considered the main pathogens responsible for acute gastroenteritis in dogs 1. CPV was fi rst identifi ed in the late 1970s as a major ca
5、use of haemorrhagic gastro- enteritis and myocarditis in puppies 2. CPV has a small single-stranded DNA genome of 5.2 kilobases (kb). Symptoms of CPV infection vary from mild to haemor- rhagic enteritis , fever, vomiting and death in severe cases. Coronaviruses are single-stranded, positive-sense RN
6、A viruses with a large genome of 27-31 kb in length. Enteric canine coronavirus typically causes mild enteritis in dogs, with more severe clinical signs observed in young animals 3. The single-stranded genome of CPV makes the virus more susceptible to modifi cations, and error-prone repli- cation ca
7、n lead to signifi cant DNA sequence variation and greater potential for evolution of these viruses, when measured over defi ned periods, or during growth of CPV through serial passage in cell culture 4. It is presumed that CPV originated from feline panleukopenia virus via genetic mutations and evol
8、ution 2. Shortly after its emergence, CPV-2 was entirely replaced by a new type, designated CPV-2a, which possessed the ability to infect both cats and dogs 5. In the mid-eighties, another type, designated as CPV-2b, began to emerge. CPV-2b is dis- tinguished from CPV-2a by a single amino acid (aa)
9、sub- stitution, asparagine (Asn) to aspartic acid (Asp), at position 426 of the major antigenic site of the VP2 capsid protein 6. In 2000, a novel CPV type, called CPV-2c, was detected in Italy, and this is now progressively replacing other CPV types 7. CPV-2c has since been detected throughout part
10、s of Europe, including Spain 8, Germany 9, Portugal 10, the United Kingdom 11, as well as Korea 12, the United States 13, South America 14 and Vietnam 15. CPV-2c is distinguishable from CPV-2a or 2b by substitution of glutamic acid (Glu) in place of Asn or Asp, respectively, at the 426thaa residue o
11、f the VP2 protein. Therefore, due to the positioning of these aa substitutions in an antigenic site, it is possible to differentiate between types by employing monoclonal antibodies 15. Alternatively, the nucleotide sequencerequiredtosubstituteGluataaposition 426 created a novel MboII restriction si
12、te (GAAGA), which is unique to CPV-2c, and therefore, CPV-2c can be S. McElligott ? P. J. Collins ? R. D. Sleator ? H. OShea ( however, a recently characterized strain detected in Italy (CB/05) resulted in a fatal disease as a consequence of systemic spread of the virus 24. Deaths have also been cau
13、sed by the synergistic effect produced when a mixed infection occurs with other canine enteric viruses. Mixed infections have been reported between CCoV and CPV-2, canine distemper virus and canine adenovirus type I 8, 26, 27. Mixed infections have also been reported between CPV-2 and calicivirus 28
14、, 29. Dual infection results in illnesses that are usually more severe than either virus can produce alone 28. Synergistic mechanisms are common with other gastroenteritis viruses such as rotavirus. Studies have demonstrated this effect with calves co-infected with group A rotavirus and group C rota
15、virus, or with group A rotavirus and Escherichia coli 30, 31. The original CPV-2 strain is still employed in many commercial vaccines. However, this strain was entirely replaced by its variant types (CCoV-I and II) shortly after its emergence. There is concern that these current vaccines may fail to
16、 protect pups against the CPV-2 variants 32, 33. A plan to use current strains in vaccine formu- lations has led to a CPV-2b-based vaccine being licensed in Europe 34. Currently, all canine vaccines used to protect against CCoVs are based on CCoV-II. However, it has been shown that the level of cross-reactivity between CCoV-I and II is limited 35. Recombinant CCoVs have been reported that were derived from CCoV-II and trans- missible gastroenteritis virus of swine (TGEV), related in the N termin
