Recent epidemiological status of feline upper respiratory infections in Japan

Occurrence of Chlamydiaceae and Chlamydia felis pmp9 Typing in Conjunctival and Rectal Samples of Swiss Stray and Pet Cats

Chlamydia (C.) felis primarily replicates in feline conjunctival epithelial cells and is an important cause of conjunctivitis in cats. Data on C. felis infection rates in stray cats in Switzerland has been missing so far. We performed a qPCR-based Chlamydiaceae-screening on 565 conjunctival and 387 rectal samples from 309 stray and 86 pet cats followed by Chlamydia species identification and C. felis typing using the gene pmp9, which encodes a polymorphic membrane protein. Overall, 19.1% of the stray and 11.6% of the pet cats were Chlamydiaceae-positive with significantly higher rates in cats displaying signs of conjunctivitis (37.1%) compared to healthy animals (6.9%). Rectal shedding of Chlamydiaceae occurred in 25.0% of infected cats and was mostly associated with concurrent ocular positivity (87.5%). In 92.2% of positive conjunctival and rectal samples, the Chlamydia species was identified as C. felis and in 2.6% as C. abortus. The C. felis pmp9 gene was very conserved in the sampled population with only one single-nucleotide polymorphism (SNP) in one conjunctival sample. In conclusion, C. felis strains are circulating in Swiss cats, are associated with conjunctivitis, have a low pmp9 genetic variability, and are rectally shed in about 16% of positive cases.

Development of a novel reverse transcription PCR and its application to field sample testing for feline calicivirus prevalence in healthy stray cats in Korea

Background

Feline calicivirus (FCV) is a major and highly infectious pathogen in cats worldwide. However, there have been limited studies about the status of FCV infections in Korea.

Objectives

To investigate the current status of FCV infections in stray cats in Korea.

Methods

A novel reverse transcription polymerase chain reaction (RT-PCR) assay was developed based on the conserved nucleotide sequences of reported FCV strains. Field swab samples were collected from 122 cats (2 hospital admitted cats and 120 stray cats) in 2016 and 2017. All the samples were tested by virus isolation and 2 different RT-PCRs, including the novel RT-PCR, for the detection of FCV.

Results

The novel RT-PCR assay showed no cross-reactivity to the nucleic acids of the other feline pathogens tested, and the limit of detection was calculated as 10⁰ TCID₅₀/mL based on an in vitro assessment. The novel RT-PCR assay detected 5 positive samples from the 122 field samples, which showed perfect agreement with the results of the virus isolation method. In contrast, another RT-PCR assay used in a previous study in Korea detected no positive samples. The prevalence of FCV infection in stray cats was 2.5% (3/120) based on the results of virus isolation and the novel RT-PCR assays.

Conclusions

The current study is the first report of the detection and prevalence of FCV in stray cats in Korea. The novel RT-PCR assay developed in this study showed high sensitivity and specificity, which indicates a useful diagnostic assay to identify FCV infection in cats.

Intranasal immunization with inactivated feline calicivirus particles confers robust protection against homologous virus and suppression against heterologous virus in cats

The protective efficacy of intranasal (IN) administration of inactivated feline calicivirus (FCV) vaccine against homologous or heterologous FCV infection was investigated. Groups of cats immunized with the experimental inactivated, non-adjuvanted FCV vaccine via either the IN or subcutaneous (SC) route were exposed to homologous or highly heterologous FCV. Both the IN and SC immunization protocols established robust protection against homologous FCV infection. Although neither immunization regimen conferred protection against the heterologous strain, clinical scores and virus titres of oral swabs were lower in cats in the IN group compared to those in the SC group, accompanying a faster neutralizing antibody response against the heterologous virus in cats in the IN group. The IN group secreted more IgA specific to FCV proteins in oral washes (lavage fluids from the oral cavity) than the SC group. IN immunization with an inactivated whole FCV particle, which protects cats from homologous virus exposure and shortens the period of heterologous virus shedding, may serve as a better platform for anti-FCV vaccine.

Prevalence of feline herpesvirus-1, feline calicivirus, Chlamydophila felis and Mycoplasma felis DNA and associated risk factors in cats in Spain with upper respiratory tract disease, conjunctivitis and/or gingivostomatitis

Objectives Our objective was to perform the first multicentric study in Spain to evaluate the prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), Chlamydophila felis and Mycoplasma felis in cats with upper respiratory tract disease (URTD), conjunctivitis and/or gingivostomatitis (GS) compared with control cats; and to evaluate risk factors for these clinical conditions. Methods Conjunctival and oropharyngeal swabs were collected and a questionnaire regarding signalment, lifestyle, vaccination history and clinical signs was obtained for each cat. Swabs were tested for each pathogen by real-time PCR. Results The study population consisted of 358 cats, including 98 control cats. Among the 260 diseased cats, 127 cats presented with URTD, 149 cats had conjunctivitis, 154 cats were suffering GS; many cats presented more than one clinical condition. The prevalence observed of FHV-1, FCV, C felis and M felis was, respectively, 28.3%, 48.0%, 20.5% and 46.5% in cats with URTD; 24.2%, 43.6%, 19.5% and 38.3% in cats with conjunctivitis; and 15.6%, 58.4%, 9.1% and 37.7% in cats with GS. Prevalences in the control group were 6.1%, 15.3%, 2.0% and 20.4%, respectively. Coinfections were common among all groups of cats. Risk factors were identified for all groups. FHV-1, FCV and C felis were associated with URTD and conjunctivitis. FCV was strongly associated with GS. M felis was present in a high percentage of the population in all groups, but its role in these clinical conditions remains uncertain. Vaccination was protective for URTD and GS but not for conjunctivitis. Conclusions and relevance This epidemiological study describes, for the first time, prevalence for FHV-1, FCV, C felis and M felis in Spain. In general, the prevalences found are similar to those reported in other countries. Factors associated with disease expression were also identified, which are relevant for practitioners.

Feline calicivirus: a neglected cause of feline ocular surface infections?

OBJECTIVE

To investigate the prevalence of feline calicivirus (FCV) infection in relation to ocular surface lesions in cats with upper respiratory tract diseases (URTD).

ANIMALS STUDIED

Ninety-nine cats with ocular surface infection and symptoms or recent history of URTD were examined at various rescue shelters and hospitals.

PROCEDURE

A complete general and ophthalmic examination was performed including Schirmer tear test, slit-lamp biomicroscopy, fluorescein and lissamine green staining. Clinical and ocular symptoms were scored and recorded. Conjunctival samples were collected using a cytobrush, and nucleic acid extraction using RT-PCR was carried out to analyze for the presence of various infectious agents.

RESULTS

RT-PCR detected either FCV, feline herpes virus type 1 (FHV-1), Chlamydophila felis or Mycoplasma spp. in 63/99 samples. 30/63 samples were positive for FCV, 23/63 for C. felis, 21/63 for Mycoplasma spp., and 16/63 for FHV-1. Out of the 30 FCV-positive samples, 11 were positive only for FCV and in 19 samples FCV was seen in combination with other agents. FCV infection was highest in animals examined at the rescue centers and in the age group of 0-2 months. Erosive conjunctivitis was an important ocular finding. Oral ulcers were detected in all FCV-infected cats.

CONCLUSION

Results indicate that FCV is highly prevalent in cats with URTD either as a sole infectious agent or in combination with other pathogens and therefore is a potential cause for ocular surface lesions during the URTD.

Chlamydophila felis in cats--are the stray cats dangerous source of infection?

Chlamydophila felis is a causative agent of acute or chronic conjunctivitis, and pneumonia in cats. Natural transmission mostly occurs consequently to close contact with other infected cats, their aerosol and fomites. We have examined 93 cats with symptoms of acute or chronic conjunctivitis, from Košice region in Slovakia, during the period of 2 years. Conjunctival samples were obtained from 55 domestic cats (59.14%) and 38 stray cats (40.86%). Of the total number of 93 examined animals, 42 cats were positive, which represents 45.16% overall positivity. Out of the 42 positive cats, 25 cats were stray and 17 positive cats were classified as domestic, which means that of 38 stray cats, 25 were positive (which represented 65.78% positivity) and of 55 domestic cats, 17 were positive (positivity was 30.90%). Our results showed that cats, especially stray cats, could be a dangerous source of chlamydiosis for humans.

Retrospective study to characterize post-obstructive diuresis in cats with urethral obstruction

Urethral obstruction is a common medical emergency in cats. Frequency of post-obstruction diuresis in cats following resolution of urethral obstruction is unknown. The objective of this study was to document frequency and associated clinical features of post-obstruction diuresis in cats. The records of 32 cats undergoing 33 admissions to the Colorado State University Veterinary Hospital for urethral obstruction were reviewed. Signalment, admission blood values, fluid therapy, and urine output were recorded. Diuresis was defined as urine output greater than 2ml/kg/h. Post-obstructive diuresis occurred in 46% (13/28) of cats within the first 6h of treatment. Occurrence of post-obstructive diuresis was statistically more likely in cats with venous pH<7.35 on admission. Urine production following resolution of urethral obstruction should be monitored so that fluid therapy can be adjusted to the individual patient, as many cats will have a higher fluid requirement secondary to post-obstruction diuresis.

Efficacy of a new inactivated Chlamydophila felis vaccine in experimentally-infected cats

A new inactivated and adjuvanted Chlamydophila felis vaccine was developed and its efficacy in cats was compared with that of commercially available inactivated and live vaccines. Two commercial vaccines conferred insufficient immunity on inoculated cats, as evaluated by antibody production and a challenge experiment, whereas cats administered the newly generated vaccine produced high-titre antibodies and acquired sufficient immunity. The cats immunised with the new vaccine revealed no or only mild clinical signs, and no chlamydiae were recovered from their tissue samples after exposure to a virulent C felis. However, they shed chlamydiae in their nasal and conjunctival secretions after challenge, as did those immunised with the commercial vaccines and the non-vaccinated controls. The newly developed vaccine caused no adverse reaction in the inoculated cats. These findings suggest that the new vaccine prepared here may be promising for practical use in controlling C felis infection in cats.

Immunological and genetic characterization of feline caliciviruses used in the development of a new trivalent inactivated vaccine in Japan

Although vaccination against feline calicivirus (FCV) infection is widespread in Japan, FCV-associated diseases are still a significant problem in cats. Thus, we developed a new trivalent inactivated vaccine, Kyoto Biken Feline-CPR, consisting of three FCV strains; one was the production strain of our previous vaccine, and the others were screened from 60 field isolates obtained between 1998 and 2000 based on cross-neutralization tests. In this report, the three FCV strains used for development of the new vaccine were antigenically and genetically characterized. The three strains were antigenically quite different, as revealed by cross-neutralization tests. Alignment of deduced amino acid sequences of capsid regions A to E revealed that there were marked differences between the strains in both the N- and C ends of region E. Antisera against the three vaccine strains, our new vaccine and 2 commercial vaccines were then evaluated for neutralization with 58 field isolates collected between 2003 and 2006. Rat antisera against the three vaccine strains and a mixture of the 3 strains neutralized 49, 37, 42 and 55 isolates, respectively. Cat antiserum against the new vaccine neutralized 50 (86.2%) isolates, whereas the numbers neutralized by cat antisera against 2 commercial vaccines were 37 (63.8%) and 25 (43.1%). In conclusion, the immunological and genetic properties of the 3 vaccine strains investigated varied widely, and the Kyoto Biken Feline-CPR vaccine may have more potential to meet the antigenic diversity of FCVs spreading throughout Japan.

Prevalence of feline herpesvirus 1, feline calicivirus and Chlamydophila felis in clinically normal cats at a Korean animal shelter

The prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), and Chlamydophila (C.) felis was studied in cats of an animal shelter in Korea. Total 78 cats without ocular and upper respiratory tract disease were examined. Specimens were obtained from ocular conjunctiva and oropharynx. Using multiplex polymerase chain reaction (PCR) and reverse transcription PCR, three pathogens were simultaneously detected. In examined 78 cats, 49 (63%) cats were positive for FHV-1. However, all specimens were negative for C. felis and FCV. In conclusion, many cats recovered from FHV-1 infection remain subclinical carriers in shelter environment.

Sensitivity of FCV to recombinant feline interferon (rFeIFN)

Feline calicivirus cause feline respiratory diseases, and inactivated and attenuated vaccines are available for its prevention. Moreover, the presence of vaccine breakdown strains (VBS) is problematic. In Japan, feline recombinant interferon (rFeIFN) has been used for its treatment. However the method of compare with each strains has not established. To examine the relationship between the breakdown vaccine strain and rFeIFN sensitivity, the sensitivity of 47 field isolates to rFeIFN was determined. The Log PDD(50) values were normally distributed within the range 1.1-3.7, with a mean value of 2.3 +/- 0.64. Since 68.3% of the PDD values fell in the range of the mean +/- standard deviation, the values in the range 1.7-2.9, the lower values, and the higher values were defined as representing moderate, low, and high sensitivity, respectively. Among the 15 vaccine breakdown strains, strain Fukuoka9 showed a low sensitivity, but strains ML89, T58, and N74 were highly sensitive, showing no association with vaccine breakdown. The amino acid sequence changes specific to the low rFeIFN-sensitive Fukuoka-9 strain were found, suggesting that these sites are involved in rFeIFN sensitivity.

FCV-VBS isolated from cats with typical symptoms caused VSD in experimental cats

Commercially available vaccines have been used widely to prevent feline calicivirus infection (FCI). However, with their widespread use, field strains, which are weakly cross-reactive with the live-virus vaccine strain F9, have posed the problem of vaccine breakdown. Recently the existence of FCV--associated virulent systemic disease (VSD) has been published. But their molecular diversity, antigenic mutations and physicochemical property have not been sufficiently clarified. Thus, we experimentally gave the vaccine breakdown strain (VBS) H10 to cats that had been inoculated with an F9 live vaccine. After the administration of strain H10, vaccinated cats (1 through 4) had no respiratory symptoms, whereas the non-vaccinated cat 5 showed clinical symptoms such as a fever of over 40 degrees C, loss of vitality, decreased appetite, diarrhea, and nasal discharge after receiving strain H10, and died. Lethal FCV is rare, and may be a virulent systemic disease (VSD)--inducing strain. This is the initial report on VSD in Japan. It has been reported that symptoms of VSD were similar in vaccinated and nonvaccinated cats on experimental infection. However, no VSD-like symptoms developed, and the incidence of the disease varied depending on the presence or absence of vaccination, suggesting that there are two mechanisms of vaccine breakdown: one is associated with the vaccine immunity level, and the other is not. The characteristics of the VBS revealed were: (1) the duration of virus excretion was short when the originally carried antibody titer before virus challenge was high, (2) the excreted viral molecular species varied daily, not being limited to a specific species with time, and (3) the acquired physicochemical properties did not persist, and altered daily. FCV-VBS alters the molecular species and physicochemical properties daily due to the reduction of host immunity, which may lead to VSD.

Feline calicivirus

Feline calicivirus (FCV) is an important and highly prevalent pathogen of cats. It belongs to the family Caliciviridae which includes other significant pathogens of man and animals. As an RNA virus, high polymerase error rates convey upon FCV a high genome plasticity, and allow the virus to respond rapidly to environmental selection pressures. This makes the virus very adaptable and has important implications for clinical disease and its control. Being genetically diverse, FCV is associated with a range of clinical syndromes from inapparent infections to relatively mild oral and upper respiratory tract disease with or without acute lameness. More recently, highly virulent forms of the virus have emerged associated with a systemic infection that is frequently fatal. A proportion of FCV infected cats that recover from acute disease, remain persistently infected. In such cats, virus evolution is believed to help the virus to evade the host immune response. Such long-term carriers may only represent a minority of the feline population but are likely to be crucial to the epidemiology of the virus. Vaccination against FCV has been available for many years and has effectively reduced the incidence of clinical disease. However, the vaccines do not prevent infection and vaccinated cats can still become persistently infected. In addition, FCV strain variability means that not all strains are protected against equally. Much progress has been made in understanding the biology and pathogenesis of this important feline virus. Challenges for the future will necessarily focus on how to control the variability of this virus particularly in relation to emerging virulent strains and vaccination.

Genogrouping of Vaccine Breakdown Strains (VBS) of Feline Calicivirus in Japan

Although prevention of feline calcivirus (FCV) infection by vaccination has been attempted, and isolation of FCV, development of the disease, and a few fatal cases in vaccinated cats have been reported. Fifteen FCV strains isolated from cats that had been vaccinated with commercially available FCV vaccines (F9, FCV-255, and FC-7) were genogrouped. Molecular analysis of viral genomes involved the construction of a phylogenetic tree of capsid genes using the NJ method. Cat anti-F9 serum and rabbit anti-FCV-255 serum were used for virus neutralization tests. Molecular phylogenetic analysis of the amino acid sequences of 15 virus isolates and those of the previously published and GenBank-deposited 9 global and 14 Japanese strains showed that 8 (53%) of the 15 virus isolates as well as the vaccine strains F9 and FCV-255 belonged to genogroup I (G(A)I), and 7 (47%) belonged to genogroup II (G(A)II). Of the 8 G(A)I strains, 2 were isolated from cats that had been vaccinated with an F9 strain live vaccine, 5 from cats vaccinated with an FCV-255-derived vaccine, and 1 from a cat vaccinated with an FC-7-derived vaccine. Of the 7 GAll strains, 5 were isolated from cats that had been vaccinated with the F9 strain live vaccine, 1 from a cat vaccinated with the FCV-255-derived vaccine, and 1 from a cat vaccinated with the FC-7-derived vaccine. These results indicate that more vaccine breakdown strains isolated from the cats vaccinated with the F9 strain-derived vaccine belong to G(A)II than to G(A)I, whereas more vaccine breakdown strains isolated from the cats vaccinated with the FCV-255 strain-derived vaccine belong to G(A)I than to G(A)II, and that when the FC-7 strain-derived vaccine is used, the vaccine breakdown strains belong almost equally to G(A)I and G(A)II. Thus, the genogroups of virus isolates varied with the vaccine strain used (p < 0.05). On the other hand, the neutralizing titres of feline anti-F9 serum and rabbit anti-FCV-255 serum against the 15 isolates were very low, showing no relationships between neutralizing antibody titres and genogroups. The DNA sequence identities between the virus isolates and the vaccine strains were low, at 70.6-82.9%, and no strains were found to have sequences derived from the vaccine strains. Alignment of amino acid sequences showed that the G(A)I or G(A)II virus isolates from the F9-vaccinated cats differed at position 428 of the 5' hypervariable region (HVR) of capsid region of the F9 strain, whereas those from the FCV-255-vaccinated cats differed at positions 438, 453, and 460 of the 5'HVR of capsid region E of the F9 strain. We speculate that these differences influence genogrouping. The amino acid changes within the F9 linear epitopes common to G(A)I and G(A)II were noted at positions 450, 451, 457 of 5'HVR of the capsid region E in the isolates from F9-derived vaccine-treated cats, and 449, 450, and 451 of 5'HVR of capsid region E in the isolates from FCV-255-derived vaccine-treated cats, suggesting that these amino acid changes are involved in escapes. These results suggest that alternate vaccination with the F9 and FCV-255 strains or the use of a polyvalent vaccine containing GAll strains serves to inhibit development.

The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel Report

Vaccination is a medical procedure, and the decision to vaccinate should be based on a risk-based assessment for each cat and each vaccine.

Detection of Feline calicivirus (FCV) from Vaccinated Cats and Phylogenetic Analysis of its Capsid Genes

We analysed genogroups of four feline calcivirus (FCV) isolates (FCV-S, H10, Ao198-1 and ML89) obtained from cats that experienced FCV infection after having been vaccinated against FCV. New PCR primer sets (8F/8R, Ao-S/Ao-A, cp-S/cp-A) were also designed, since the conventional Seal primer failed to amplify the target sequences in two samples. The genogroups of the four isolates as well as eight global and 17 domestic strains were determined by phylogenetic analysis of their amino acid sequences. One out of the four strains (25%) isolated in this study, H10, was grouped into genogroup I, along with the vaccine strains F9 and FCV-255. The other three isolates (75%) belonged to genogroup II. Thus, there were more isolates in genogroup II than in genogroup I. However, the antibody values of the four isolates against cat anti-F9 antisera were significantly decreased. There may be no relationship between the neutralizing antibody titre and genogroup. Amino acid sequence alignment of the four isolates showed that only a single amino acid in region C, which is involved in neutralization epitopes, was different in ML89 strain from that of F9. The other three strains, H10, Ao198-1 and FCV-B, shared the same amino acid sequence with F9. Alignment of amino acids for linear epitopes in the F9 strain, which are located at regions D and E, showed variations in 5' hypervariable region (HVR) of E, whereas D and conE had only synonymous substitutions i.e. no change in the amino acid sequence. This mutation in 5' HVR of region E suggested a vaccine breakdown, as the region is known to be essential for antigenicity. The genogroup II FCV is likely to be the cause of the FCV infection in this study, while the vaccine strains belong to genogroup I. Thus, the existing vaccine may need reevaluation for its effectiveness.

Isolation of feline herpesvirus-1 and feline calicivirus from healthy cats in Swedish breeding catteries

Feline calicivirus (FCV) could be isolated from four cats (2.6%) and feline herpesvirus-1 (FHV) from none of 152 clinically healthy cats from 22 Swedish breeding catteries. These cats had all previously shown signs of respiratory tract disease or conjunctivitis, although several years ago. The results suggest that carriers of FCV and FHV were uncommon in Swedish breeding catteries studied. Prevalence rates in other European countries and North America are usually higher, especially of FCV. The lower prevalence rates in our study might be explained by test group selection, differences in factors such as management, environment, or genetic constitution of the cats, or by sample handling. It was concluded that the presence of an FCV shedder in the cattery does not mean that all cats in the group are infected, but special measures are recommended to avoid infection of susceptible cats.

A novel genetic marker to differentiate feline herpesvirus type 1 field isolates

Five recent field isolates of feline herpesvirus type 1 (FHV-1) were compared by digestion with a restriction endonuclease, SalI or MluI. The SalI digestion showed a potentially useful difference in one isolate 00-035 that had an approximately 3.0 kbp fragment instead of a 2.6 kbp fragment in the other strains. After cloning the 3.0 and 2.6 kbp fragments, the nucleotide sequences were analyzed. The result showed that the 3.0 kbp fragment of 00-035 included a complete open reading frame of the herpes simplex virus 1 (HSV-1) homologue of the UL17 gene and a 5'-part of UL16 gene and that only one nucleotide substitution was found in the 5'-region of UL17 gene where the SalI site of the 2.6 kbp fragment locates. Based on these nucleotide sequences, two PCR primers were designed to amplify the region around the SalI site in the UL17 gene and the PCR was carried out using 78 field isolates from various parts of Japan. The SalI digestion of the PCR products revealed an interesting profile in that the genotype without the SalI site in UL17 gene was dominant in Tottori and Yamagata prefectures (69% and 75%, respectively) but minor in the other regions of Japan (0-10%). These results suggest that the SalI digestion method described in the present study can be used as a genetic marker to differentiate some FHV-1 field isolates and this is the first report that showed different distributions of FHV-1 genotypes using the novel genetic marker.

Detection of novel chlamydiae in cats with ocular disease

OBJECTIVE

To detect and characterize the full range of chlamydial infections in cats with ocular disease by use of polymerase chain reaction (PCR) assays, cytologic examination, immunohistochemical analysis, and evaluation of clinical information including status for feline herpesvirus-1 (FeHV-1).

SAMPLE POPULATION

DNA extracted from 226 conjunctival samples obtained from cats with clinically diagnosed keratitis or conjunctivitis and 30 conjunctival samples from healthy cats.

PROCEDURE

PCR assays for the 16S rRNA gene specific for the order Chlamydiales and a new Chlamydophila felis (formerly Chlamydia psittaci) species-specific 23S rRNA gene were performed. Seventy-four conjunctival samples were prepared with Romanowsky-type stain, grouped on the basis of inflammatory pattern, and screened for chlamydial inclusions by use of immunohistochemical analysis. Clinical information and FeHV-1 status were recorded.

RESULTS

26 (12%) specimens had positive results for the only known feline chlamydial pathogen, C felis. Surprisingly, an additional 88 (39%) were positive for non-C felis chlamydial DNA. Identification of non-C felis chlamydial DNA by direct sequencing revealed 16S rRNA gene sequences that were 99% homologous to the sequence for Neochlamydia hartmannellae, an amebic endosymbiont. Chlamydial prevalence was significantly higher in cats with ocular disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Application of a broad-range detection method resulted in identification of a new agent associated with ocular disease in cats. Finding chlamydia-like agents such as N hartmannellae in coinfections with their obligate amebic host, Hartmannella vermiformis, raises questions about the potential role of these microorganisms in causation or exacerbation of ocular disease in cats.

Radiographic signs in cats with nasal disease

Radiographic signs in 64 cats that had radiography as part of the diagnostic work-up for suspected nasal disease were reviewed in a blinded fashion. Final diagnoses in these cats were rhinitis in 27, primary nasal neoplasia in 21 and non-nasal disease in 16. The signs with highest predictive value for nasal neoplasia were displacement of midline structures (73%), unilateral generalised soft tissue opacity (70%), unilateral generalised loss of turbinate detail (69%) and evidence of bone invasion (64%). The only radiographic finding that occurred more frequently in cats with rhinitis was a nasal cavity within normal limits, and the predictive value of this sign was only 38%. Radiographic signs in cats with nasal neoplasia are similar to those reported in dogs, whereas the radiographic signs in cats with rhinitis are variable and non-specific, and may be absent.

Experimental infection of recent field isolates of feline herpesvirus type 1

Two field isolates of feline herpesvirus type 1 (FHV-1) designated as 00-015 and 00-035, were obtained from cats diagnosed as feline viral rhinotracheitis (FVR) in Japan. To analyze the character of recent FHV-1, these two isolates and our laboratory strain C7301 were inoculated experimentally to specific-pathogen-free cats. Although all cats showed typical FVR symptoms, more severe clinical symptoms were observed on cats infected with the isolates 00-015 and 00-035 compared with those of C7301-infected cats. Severe ocular lesions including conjunctivitis were found in the cats infected with the isolates, indicating that the recent FHV-1 has a potential to induce severe FVR symptoms including ocular lesions.

Chlamydial infection of cats and human health

Chlamydia psittaci var. felis is considered as a primary and important agent in the etiology of infectious diseases of the upper respiratory tract and eyes in cats, having zoonotic potential. We investigated 13 cats aged between 2 months and 7 years, in which conjunctivitis, rhinitis, laryngotracheitis, bronchopneumonia and lymph adenopathy was clinically diagnosed. To detect the antigen of C. psittaci the Clearview Chlamydia Direct Test was used for the first time. The presence of C psittaci in 10 of 13 investigated cats and in 8 nasal mucosa smears from 10 investigated cats were confirmed in conjunctiva. Using bacteriological examination different species of the genus Staphylococcus in conjunctiva from all 13 investigated animals were also confirmed. Serological investigation using complement fixation test was negative in all animals.

Experimental infection of cats with Chlamydophila felis

Cats experimentally infected with a British isolate of Chlamydophila felis (C. felis), B166 strain, by droplet into the eye and nose developed conjunctivitis, mild rhinitis and fever. The chlamydophila were first isolated from conjunctiva, nictitating membrane and then from lung, tonsil, liver, spleen, kidney, nasal and vaginal swabs and blood. These results indicate that C. felis B166 strain first infected and replicated in the conjunctiva and nictitating membrane in cats with symptoms which were mostly limited to conjunctivitis, and then pervaded the whole body by bacteremia.

An etiological investigation of domestic cats with conjunctivitis and upper respiratory tract disease in Japan

Chlamydophila felis (C. felis), feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV) were detected in 39 (59.1%), 11 (16.7%) and 14 (21.2%) cats respectively, from 66 domestic cats presented with conjunctivitis and upper respiratory tract disease (URTD) in 9 prefectures of Japan. Dual and multiple infections were found in 7 (10.6%) cats with both C. felis and FHV-1, 10 (15.2%) cats with both C. felis and FCV, and 1 (1.5%) cat with all three agents. C. felis was isolated from 11 (28.2%) of 39 PCR positive cats. Antigenic difference was found in a 96 kDa protein of our isolates and Fe/145 strain isolated in USA. In conclusion, C. felis is the most common agent of feline conjunctivitis and URTD, and the coinfection with C. felis, FHV-1 and FCV are also common in cats in Japan.

Isolation of chlamydia psittaci from domestic cats with oculonasal discharge in Japan

Eight strains of Chlamydia psittaci were isolated in Japan from the nasal and conjunctival swabs of six household cats using the L929 cell line of mouse fibroblast origin. The isolates were identified as C. psittaci on the basis of the formation of characteristic inclusion bodies in the cell culture detected by Giemsa stain and immunofluorescence. Comparison of nucleotide sequences of the ompA gene amplified from the three isolates with the published sequence of feline FEPN strain of C. psittaci showed almost 100% homology.