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Abstract

Objective

To characterize 2 strains of Haemobartonella felis by use of molecular techniques.

Animals

35 specific-pathogen-free cats, 6 months to 4 years old.

Procedure

Intraperitoneal or IV inoculation with blood containing H felis small form (Hfsm, 18 cats) or H felis large form (Hflg, 11 cats); 6 cats were uninfected controls. Hfsm was evaluated for capability to cross-protect against the more virulent Hflg. Morphology of both strains was compared by light microscopy of Wright-Giemsa-stained blood smears, and the 16S rRNA genes were sequenced.

Results

Infection with Hflg induced signs of depression, fever, and severe macrocytic normochromic anemia with nucleated erythrocytes. More than 95% of erythrocytes were parasitized. Inoculation with Hfsm and uninfected control blood induced mild or no clinical signs and no hematologic abnormalities. Anti-Hfelis lgG was first detected on postinoculation day (PID) 21, and increased to maximal titer of 400 by PID 28. Reactivated infection was observed in 8 of 29 cats (4 Hfsm and 4 Hflg), with 5% parasitized erythrocytes during the later attack. On PID 8, Hflg-inoculated cats had positive results of polymerase chain reaction analysis (PCR) that persisted until cats were treated with doxycycline or oxytetracycline; Hfsm-inoculated cats had positive PCR results that persisted for duration of observation (3 months).

Conclusions

Genetically and morphologically distinct strains of H felis infect cats in the field. The level of genetic difference suggested that these strains may be different species or genera.

Clinical Relevance

PCR is a critical diagnostic aid to detect occult Haemobartonella spp infection, as well as response to treatment and clearance of the organism. (Am J Vet Res 1998;59:1581-1588)

Free access
in American Journal of Veterinary Research

Summary

The clinicopathologic manifestations of bovid herpesvirus-4 (bhv-4; FCAHV strain)-induced infection of the lower portion of the urinary tract were characterized in 12 adult neutered male and 6 female specific-pathogen-free cats, and were compared with those in 12 neutered male control cats. Six neutered male and 6 female cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with bhv-4. Six neutered male control cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with uninfected tissue culture control inoculum. Six additional neutered male control cats were exposed only to uninfected tissue culture control inoculum. All cats were observed for 90 days following inoculation. Dysuria and gross hematuria were observed in only 1 bhv-4-exposed cat. Radiographic abnormalities of the lower portion of the urinary tract were not observed. Microscopic hematuria, crystalluria, and lipiduria were identified with similar frequency in bhv-4-exposed and control cats. Results of urine culturing for bacteria, mycoplasma, ureaplasma, and viruses were negative. Viruses were not isolated from blood leukocytes collected from exposed or control cats. Three to 6 weeks after inoculation, high concentrations of bhv-4 serum antibodies were detected in all exposed cats by an indirect fluorescent antibody test.

Light microscopic examination of the urinary tract revealed multifocal lymphoid cystitis in 2 bhv-4-exposed cats. Except for suppurative bronchitis in 1 bhv-4-exposed cat given glucocorticoids, morphologic differences in urinary and extraurinary tissues were not observed. In urinary bladder tissue collected 90 days after inoculation, bhv-4 was reisolated from urinary bladder explants of all but 1 exposed cat. Virus was also isolated from a kidney explant of 1 exposed male cat, and spleen cell cocultures of 1 exposed female cat given glucocorticoids.

Bovid herpesvirus-4 (FCAHV strain) caused persistent urinary tract infections in male and female specific-pathogen-free cats. Detection of occult bhv-4 infection required isolation of virus from tissues by explantation, or demonstration of specific bhv-4 antibodies by immunofluorescent techniques. Administration of glucocorticoids prior to inoculation did not enhance morbidity associated with bhv-4 urinary tract infection. Further investigations are needed to determine the pathogenic role of bhv-4 in noninduced feline lower urinary tract disease.

Free access
in American Journal of Veterinary Research