Ocular manifestations of systemic diseases.

The diseases included in this article constitute a wide range of maladies that affect the horse. Certainly, the diseases that are known today to produce ocular lesions are just a few of what will be discovered if attending veterinarians always examine the eyes of patients with systemic diseases.     

Ocular manifestations of hyperlipoproteinaemia

The ocular manifestations of hyperlipoproteinaemia include visible lipaemia of ocular blood vessels, corneal opacities, lipaemic aqueous and gross infiltration of the globe itself which is easiest to observe in the peripheral cornea and uveal tract. Both primary and secondary hyperlipoproteinaemia may produce ocular signs and the ocular appearance can be characteristic of the underlying lipoprotein disorder.     

Identification of feline herpesvirus type 1-hemagglutinin

The crude hemagglutinin of feline herpesvirus type 1 (FHV-1), solubilized from infected fcwf-4 cells by detergents, was partially purified by three kinds of chromatographic methods. Lectin-affinity chromatography showed the hemagglutination (HA) activity in fractions, which was bound to Concanavalin A-sepharose and then eluted by alpha-methyl D-mannoside, suggesting that the hemagglutinin might include a glycoprotein. Ion-exchange and gel-exclusion chromatographies were also capable of purifying the detergent-soluble crude hemagglutinin. When peak HA fractions, which were obtained from each of the three procedures, were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the gel-exclusion chromatography was the most effective method. Electrophoreic analysis also showed only one band of 59,000 (59K) molecular weight protein, which was commonly observed in the three partially purified hemagglutinins with silver staining. In addition, the 59K protein band was clearly recognized in immunoblot analysis of the infected cell lysates using infected cat serum. These observations suggest that the FHV-1 detergent-soluble hemagglutinin from infected fcwf-4 cells may be closely related to a 59K immunogenic glycoprotein.     

Isolation of feline calicivirus and feline herpesvirus from domestic cats 1980 to 1989

Isolation rates of feline herpesvirus (FHV) and feline calicivirus (FCV) from oropharyngeal swabs, taken from 6866 cats in 1980 to 1989 were studied retrospectively. FCV was isolated from 1364 (19.9 per cent) and FHV from 285 (4.2 per cent). The ratio of FCV:FHV isolations varied from 1.3:1 to 15:1 in individual years with an overall ratio of 4.8:1. Isolation of both viruses was fairly uniform for each year and there was no breed or sex disposition to either virus. Of 872 cats shedding FCV and 213 cats shedding FHV, of known age, 447 (51.3 per cent) with FCV and 140 (65.7 per cent) with FHV were under one year old, compared to only 35.3 per cent of the whole population sampled. For the years 1985 to 1989, more information was obtained about the cases. Of 4626 cats tested, 1180 (25.5 per cent) had acute upper respiratory tract disease (URTD) of which 348 (29.5 per cent) were shedding FCV and 162 (13.7 per cent) FHV. A further 597 had chronic URTD and of these, 102 (17.1 per cent) were shedding FCV and 18 (3 per cent) FHV. In 120 cases of suspected vaccine reaction/breakdown, FCV was isolated from 34 (28.3 per cent) and FHV from only two (1.7 per cent). FHV was not isolated from any of 412 cases presenting with chronic gingivitis/stomatitis alone; 181 (43.9 per cent) were shedding FCV and when cats with other signs in addition to chronic gingivitis were included, this proportion increased to 70.4 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intracellular localization and epitope mapping of feline herpesvirus type 1 glycoproteins.

Monoclonal antibodies (MoAbs) were used to characterize feline herpesvirus type 1 (FHV-1) glycoproteins (gp). Intracellular localization and transport of these proteins as revealed by a sequential indirect immunofluorescence assay (IFA) on fixed infected cells showed slight differences between FHV-1 gp143/108 and gp113. Antibodies against gp143/108 first showed membrane fluorescence at 4 hrs post-infection (PI) followed by a pronounced perinuclear and cytoplasmic staining from 8 hrs PI onwards. Those reacting with gp113 showed the same pattern but fluorescence did not appear until 8 hrs PI. In contrast, MoAbs against gp60 first showed para- and perinuclear staining at 12 hrs PI which became intranuclear at 16 hrs PI, followed by intracytoplasmic staining at 20 hrs PI. Sequential IFA of unfixed infected cells revealed that the three glycoproteins were expressed on the cell surface membrane as well. Topographical mapping of the functional epitopes of gp113 by ELISA additivity test indicated the presence of 2 antigenic domains--a neutralizing domain consisting of 3 overlapping epitopes and a non-neutralizing domain. On the other hand, gp143/108 contained only one antigenic site consisting of 5 similar or overlapping epitopes, one of which seemed to be a conserved region recognized by all MoAbs reacting to this protein.     

Structure-function analysis of the feline herpesvirus virulence factors gE and gI.

The biosynthesis and function of the gE-gI complex of feline herpesvirus (FHV) was studied by heterologous expression of the cloned genes in the vaccinia virus-based vTF7-3 expression system and by analysis of FHV recombinants. This work has led to the identification of domains in gI involved in complex formation with gE, and to a model for the disulfide-bonded structure of gI. The effects of mutations in gI on gE-gI-dependent cell-to-cell transmission are discussed.     

Homologous and heterologous antibody responses of mice immunized with purified feline herpesvirus type 1 and canine herpesvirus glycoproteins.

The three glycoproteins each of feline herpesvirus type 1 (FHV-1) and canine herpesvirus (CHV) were purified by affinity chromatography using glycoprotein-specific monoclonal antibodies and used individually or in combination in immunizing mice to determine their relative immunogenicity. All the glycoproteins induced detectable virus neutralizing antibodies to the homologous virus but FHV-1 gp143/108 and its cross-reacting counterpart, CHV gp145/112, elicited the highest titers not only to the homologous virus but to the heterologous virus as well. The production of ELISA antibodies after glycoprotein immunization was variable, while hemagglutination-inhibiting antibodies were produced by only 1 out of 10 FHV-1 gp60-inoculated mice. In general, the antibody titers induced by CHV glycoproteins were lower than those by FHV-1 glycoproteins. These results indicate that these glycoproteins may be useful as subunit vaccines against FHV-1 and CHV infections.     

Isolation of feline herpesvirus 1 from a young kitten

Five kittens exposed neonatally to older cats exhibiting fever with nasal and ocular discharge became ill and died within 10 days of the onset of illness. One kitten which died at 16 days old was examined post mortem and feline herpesvirus 1 was isolated from the brain, liver, lung and spleen.     

A field trial to assess the effect of vaccination against feline herpesvirus, feline calicivirus and feline panleucopenia virus in 6-week-old kittens.

A trivalent (feline panleucopenia, feline herpesvirus, feline calicivirus), modified live, commercially available cat vaccine was used at either 6, 9 and 12 weeks of age (early schedule) or 9 and 12 weeks of age (conventional schedule), and the serological response to vaccination was assessed. The level of maternally derived antibody present at 6 weeks of age was also established. The use of early vaccination at 6 weeks of age induced an antibody response to each virus by 9 weeks of age in a significant proportion of kittens compared with unvaccinated littermates. There was no difference between the conventionally and early-vaccinated groups in terms of antibody response to any antigen by 12 and 15 weeks of age.     

A study of feline upper respiratory tract disease with reference to prevalence and risk factors for infection with feline calicivirus and feline herpesvirus.

A cross-sectional survey of a convenience sample of cats was carried out to determine the prevalence of and risk factors for respiratory tract disease, feline calicivirus (FCV) infection and feline herpesvirus (FHV) infection. Seven hundred and forty cats were studied; samples for isolation of FCV and FHV were obtained from 622 (84%). Data on individual cat and household variables were obtained by questionnaire for each cat and analysed using univariable and logistic regression analysis. Thirty-eight percent (282/740) of cats surveyed had respiratory tract disease. Eighteen of 24 predictor variables were found to be significantly (P<0.05) associated with the presence of respiratory tract disease in a cat on univariable analysis. Following logistic regression, several factors retained significance including isolation of FCV and FHV, younger cats (4-11 months of age) and multiple cat households. A negative association was found with breeding catteries and other types of household in comparison with rescue catteries. Overall, feline calicivirus was isolated from 162/622 (26%) of cats sampled; 33% of the cats with respiratory tract disease were FCV positive compared to 21% of healthy cats. Variables significantly associated with FCV isolation on logistic regression were the presence of respiratory tract disease and contact with dogs with and without respiratory tract disease. Feline herpesvirus was isolated from 30/622 (5%) of all cats sampled; 11% of cats with respiratory tract disease were FHV positive compared to 1% of healthy cats. Variables significantly associated with FHV isolation on univariable analysis included age, gender, and the presence of respiratory tract disease. Vaccination showed a negative association. Logistic regression analysis of the data for FHV was limited by the sample size and the low prevalence of FHV.