Analysis of canine parvovirus (CPV) isolates with a panel of monoclonal antibodies showed that after 1986, most viruses isolated from dogs in many parts of the United States differed antigenically from the viruses isolated prior to that date. The new antigenic type (designated CPV type 2b) has largely replaced the previous antigenic type (CPV type 2a) among virus isolates from the United States. This represents the second occurrence of a new antigenic type of this DNA virus since its emergence in 1978, as the original CPV type (CPV type 2) had previously been replaced between 1979 and 1981 by the CPV type 2a strain. DNA sequence comparisons showed that CPV types 2b and 2a differed by as few as two nonsynonymous (amino acid-changing) nucleotide substitutions in the VP-1 and VP-2 capsid protein genes. One mutation, resulting in an Asn-Asp difference at residue 426 in the VP-2 sequence, was shown by comparison with a neutralization-escape mutant selected with a non-CPV type 2b-reactive monoclonal antibody to determine the antigenic change. The mutation selected by that monoclonal antibody, a His-Tyr difference in VP-2 amino acid 222, was immediately adjacent to residue 426 in the three-dimensional structure of the CPV capsid. The CPV type 2b isolates are phylogenetically closely related to the CPV type 2a isolates and are probably derived from a common ancestor. Phylogenetic analysis showed a progressive evolution away from the original CPV type. This pattern of viral evolution appears most similar to that seen in some influenza A viruses.

Rapid antigenic-type replacement and DNA sequence evolution of canine parvovirus

Nine isolates of Canine parvovirus (CPV) were obtained from Vietnamese dogs and cats. One canine isolate showed a unique antigenic property which indicates a novel antigenic variant of CPV-2b when examined with hemagglutination inhibition tests using our monoclonal antibodies, 21C3 and 19D7, which were recently developed. This isolate had an amino acid substitution of residue 426, Asp to Glu, and the same substitution has recently been found in CPV from Italian dogs. This study first showed that such substitution caused an antigenic difference demonstrable by monoclonal antibodies and that a similar evolution may have occurred in CPV in Vietnam.

A novel antigenic variant of Canine parvovirus from a Vietnamese dog.

Acute contagious respiratory disease (kennel cough) is commonly described in dogs worldwide. The disease appears to be multifactorial and a number of viral and bacterial pathogens have been reported as potential aetiological agents, including canine parainfluenza virus, canine adenovirus and Bordetella bronchiseptica, as well as mycoplasmas, Streptococcus equi subsp. zooepidemicus, canine herpesvirus and reovirus-1,-2 and -3. Enhancement of pathogenicity by multiple infections can result in more severe clinical forms. In addition, acute respiratory diseases associated with infection by influenza A virus, and group I and II coronaviruses, have been described recently in dogs. Host species shifts and tropism changes are likely responsible for the onset of these new pathogens. The importance of the viral agents in the kennel cough complex is discussed.

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Canine respiratory viruses.

Twenty-seven feline parvovirus (FPV) isolates were recovered from cats clinically diagnosed with feline panleukopenia (FPL) for assessing antigenic and genomic properties of FPL viruses (FPLV) recently prevalent among cats in Japan. All isolates, with the exception of one novel isolate, FPV-314, possessed homologous properties, and their subgroups in FPVs were identified as FPLV. The FPV-314 isolate, which was from a 1.5-year-old cat which manifested clinical signs of FPL and died on the 13th day after the first medical examination, was finally identified as canine parvovirus (CPV) because it lacked a specific antigenic epitope commonly detected in FPLV and mink enteritis virus and because the nucleotide sequence of the capsid protein gene was almost identical to those of CPV-2a and -2b antigenic type strains recently prevalent among dogs in Japan. The present result together with our previous findings (M. Mochizuki, R. Harasawa, and H. Nakatani. Vet. Microbiol. 38:1-10, 1993) indicates the possibility that CPV and FPLV undergo mutual interspecies transmission between dogs and cats, and it is postulated that they may cause disease in some adventitious hosts.

Isolation of canine parvovirus from a cat manifesting clinical signs of feline panleukopenia.

Antigenic and genomic variabilities among recently prevalent parvoviruses of canine and feline origin in Japan.

Four monoclonal antibodies (mAb) against a feline panleukopenia virus (FPLV) TU 1 strain, one of the host range variants of feline parvovirus (FPV), were produced and applied for antigenic analysis of FPLV, canine parvovirus (CPV) and mink enteritis virus (MEV). All mAbs were considered to be directed at epitopes on the virus capsid surface because they neutralized the infectivity and inhibited the hemagglutination (HA) of the homologous virus as well as other FPV strains. They were of the mouse IgG1 type. High antigenic homogeneity among FPLV strains was confirmed by HA-inhibition (HI) test with the mAbs and polyclonal immune sera against FPLV or CPV. But the TU 11 strain of FPLV was antigenically distinguished from the remaining 14 FPLV strains by both the HI test and the micro-neutralization test with one of the mAbs produced. MEV Abashiri strain was found to be antigenically indistinguishable from FPLV. Most of the CPV strains isolated after 1981 were considered to be antigenically different from earlier CPV isolates when some mAbs were applied in the serological tests, confirming the replacement of CPV by an antigenic variant in Japan. However, antigenically different CPVs were detected at the end of 1984 from unrelated epizootics occurred a month apart in the same area.

Comparison of feline parvovirus subspecific strains using monoclonal antibodies against a feline panleukopenia virus

流行性の呼吸器症状を呈して斃死した3力月齢の仔犬の肺炎部から, 初代犬腎培養細胞に細胞病原性を示す agent を分離した. この agent は, 生物学的および理化学的諸性状, negative 染色による電顕観察, パラインフルエンザ5型ウイルスSV5との交差中和試験の結果から, パラインフルエンザウイルス5型と同定された. この分離ウイルスを経鼻接種により, 2頭の仔犬に感染試験を行なったところ, 軽い呼吸器症状が発現し, 中和抗体の上昇がみられた. また, 1958年から1977年にわたって近畿, 東海地方で集めた175例の犬血清について本ウイルスに対するHI抗体を調査した結果, 1975年以前のものはすべて陰性であったが, 1976年と1977年のものでは抗体陽性例が認められた.

Isolation and characterization of parainfluenza 5 virus from a dog.

Isolation and properties of adenovirus from canine respiratory tract.

PURPOSE:To provide a live virus vaccine effective to the respiratory diseases caused by infection with canine parainfluenza viruses and having high safety, by usig attenuated virus obtained by the extended tissue subculture of viruses. CONSTITUTION:Viruses separated from a dog affected with respiratory diseases through the first-generation dog kidney (DK)culture cells, is subcultured for four generations in DK culture cells, and then subcultured in the established cells of the kidney of green monkey (Cerocopithecus aethiops sabaeus)(Vero cell) at 30+ or -5 deg.C. for >=30 generations. The resultant viruses are inoculated in Vero cells, and cultured at 30 deg.C. At the peak of the proliferation of the virus, the infected culture liquid is collected, mixed with the sterilized liquid consisting of a protecting agent (e.g. lactose) and purified water, and freeze-dried to obtain the titled live vaccine. It has remarkable effectiveness after three weeks from inoculation of the vaccine even by the aggresive test using the attenuated CPI virus. The vaccine gives no side effect in the test using a dog negative to antibody, and the high safety.

Live virus vaccine for canine parainfluenza

The present study shows the infectivity for chicken embryos of the SPL strain of tissue-culture-modified infectious laryngotracheitis (ILT) virus. The modified virus formed small pocks on the chorioallantoic membrane (CAM) and gave no adverse reaction after administration to chickens. For 1- and 6-day-old embryonated specific-pathogen-free (SPF) eggs, the SPL strain showed higher infectivity than virulent strain NS-175 or wild strains of ILT virus. A high percentage of embryos of day-old eggs inoculated with strains SPL via the yolk sac died within several days, and virus was recovered from yolk and embryos with high titer. In the embryos inoculated at 6 days of age, histopathological lesions characterized by syncytium formation with intranuclear inclusion bodies were observed mainly in the CAM, liver cells, epithelial cells of the oral cavity, and esophagus and rarely in epithelial cells of the uriniferous tubule, bronchus, trachea, choroid plexus, or feather follicles. In the 10-day-old embryonated SPF eggs inoculated via the chorioallantoic cavity, however, the SPL strain demonstrated low pathogenicity compared with strain NS-175 and the two wild strains.

Ajiki Masayuki

Papers

Comparison of feline parvovirus subspecific strains using monoclonal antibodies against a feline panleukopenia virus

Isolation and characterization of parainfluenza 5 virus from a dog.

Isolation and properties of adenovirus from canine respiratory tract.

Live virus vaccine for canine parainfluenza

Infectivity for chicken embryos of tissue-culture-modified infectious laryngotracheitis virus.