Ehrlichia spp. in cervids from California.

Blood samples from six mule deer (Odocoileus hemionus hemionus), 15 black-tailed deer (O. hemionus columbianus), and 29 elk (Cervus elaphus nannodes) were assayed for human monocytic and human granulocytic ehrlichiosis (HGE) by polymerase chain reaction (PCR), DNA sequencing, and serology to determine whether or not cervids are involved in the maintenance of these potential human pathogens in California (USA). The deer were sampled in August to October 1992-95.

Isolation of reptilian calicivirus Crotalus type 1 from feral pinnipeds.

Ten virus isolates were obtained from three species of marine mammals sampled on San Miguel Island (California, USA) and 1,200 km north on Rogue Reef (Oregon, USA) during tagging operations in 1986-87. Seven of these 10 were derived from 30 sampled Steller sea lion (Eumetopias jubatus pups, while two of 10 were isolated from one of 19 sampled California sea lion (Zalophus californianus californianus pups, and the remaining isolate was derived from 30 sampled northern fur seal (Callorhinus ursinus) pups. All 10 isolates were identified as belonging to a single serotype, reptilian calicivirus Crotalus type 1 (RCV Cro-1), previously isolated from both healthy and diseased snakes and frogs in a California zoologic collection.

Detection of Ehrlichia risticii, the agent of Potomac horse fever, in freshwater stream snails (Pleuroceridae: Juga spp.) from northern California.

Ehrlichia DNA was identified by nested PCR in operculate snails (Pleuroceridae: Juga spp.) collected from stream water in a northern California pasture in which Potomac horse fever (PHF) is enzootic. Sequencing of PCR-amplified DNA from a suite of genes (the 16S rRNA, groESL heat shock operon, 51-kDa major antigen genes) indicated that the source organism closely resembled Ehrlichia risticii, the causative agent of PHF.

Experimental transmission of Ehrlichia equi to horses through naturally infected ticks (Ixodes pacificus) from Northern California.

We report the experimental transmission of Ehrlichia equi from naturally infected Ixodes pacificus ticks to horses. Three weeks after exposure to ticks, two of three horses developed clinical signs compatible with E. equi infection, while one horse remained asymptomatic.

Production and characterization of Ehrlichia risticii, the agent of Potomac horse fever, from snails (Pleuroceridae: Juga spp.) in aquarium culture and genetic comparison to equine strains.

We report on the production and characterization of Ehrlichia risticii, the agent of Potomac horse fever (PHF), from snails (Pleuroceridae: Juga spp.) maintained in aquarium culture and compare it genetically to equine strains. Snails were collected from stream waters on a pasture in Siskiyou County, Calif.

In vitro isolation and characterization of a calicivirus causing a vesicular disease of the hands and feet.

We report that a calicivirus of oceanic origin, San Miguel sea lion virus serotype 5 (SMSV-5), is a human pathogen. This biotype was isolated originally from blisters on the flippers of northern fur seals (Callorhinus ursinus) and replicates readily in primate and human cell lines. It infects a phylogenetically diverse array of hosts (poikilotherms to primates) and induces type-specific neutralizing antibodies in exposed humans.

Ehrlichia phagocytophila genogroup rickettsiae in ixodid ticks from California collected in 1995 and 1996.

A total of 1,246 ixodid ticks collected in 1995 and 1996 from seven California counties were examined for the presence of Ehrlichia phagocytophila genogroup rickettsiae by using a nested PCR technique. Of 1,112 adult Ixodes pacificus Cooley and Kohls ticks tested, nine pools, each containing five ticks, were positive (minimum percentage of ticks harboring detectable ehrlichiae, 0.8%).

An Ehrlichia strain from a llama (Lama glama) and Llama-associated ticks (Ixodes pacificus).

An ehrlichia was identified in the blood of a diseased llama (lama glama). Sequencing of its 16S rRNA gene showed the ehrlichia to be closely related to members of the Ehrlichia phagocytophila genogroup. The agent was also found in a pool of ticks (Ixodes pacificus) collected at the llama site.

Nested polymerase chain reaction for detection of Ehrlichia risticii genomic DNA in infected horses.

A nested polymerase chain reaction was developed for amplifying a 529-bp segment of the 16S ribosomal RNA gene of Ehrlichia risticii from equine buffy coat cells. Confirmation of identity of the amplified bands was accomplished by Southern hybridization and DNA sequencing. The study indicated a detection limit of > 10 copies of the target gene, and specificity for E.

Primary and secondary Toxoplasma gondii infection in normal and feline immunodeficiency virus-infected cats.

Normal and asymptomatic feline immunodeficiency virus (FIV)-infected adult cats were inoculated orally with Toxoplasma gondii tissue cysts to assess differences in clinical disease, T. gondii serologic test results, hematologic results, and oocyst shedding. There was no difference between FIV-naive and FIV-infected cats in terms of clinical illness and duration of oocyst shedding following primary exposure.

Nested polymerase chain reaction for detection of Ehrlichia equi genomic DNA in horses and ticks (Ixodes pacificus).

A nested polymerase chain reaction for detecting Ehrlichia equi in horses and ticks (Ixodes pacificus) was developed. A major second-round PCR product of 928 bp could be readily visualized in ethidium bromide-stained agarose minigels. An internal probe was used to verify the identity of the amplified product by non-radioactive (digoxigenin-based) Southern blotting; additional confirmation was provided by DNA sequence analysis.

Isolation of the equine granulocytic ehrlichiosis agent, Ehrlichia equi, in tick cell culture.

The equine granulocytic ehrlichiosis agent, Ehrlichia equi, is closely related or identical to the human granulocytic ehrlichiosis (HGE) agent. Both are suspected of being transmitted by ticks. We have successfully isolated E.

Equine granulocytic ehrlichiosis in Connecticut caused by an agent resembling the human granulocytotropic ehrlichia.

The first recognized cases of equine granulocytic ehrlichiosis in New England are described. The DNA sequence of the 16S rRNA gene of the causative ehrlichia was found to be identical to that of the human granulocytotropic ehrlichia, the agent of human granulocytic ehrlichiosis.

Ixodes pacificus (Acari: Ixodidae) as a vector of Ehrlichia equi (Rickettsiales: Ehrlichieae).

Ehrlichia equi, a rickettsia described from horses in California 30 yr ago, causes equine granulocytic ehrlichiosis throughout the Americas and possibly Europe. Here, we report experimental transmission of E. equi from infected to susceptible horses through bites of western blacklegged ticks, Ixodes pacificus (Cooley & Kohls).

Protection against Ehrlichia equi is conferred by prior infection with the human granulocytotropic Ehrlichia (HGE agent).

A Thoroughbred filly that developed clinical signs of equine granulocytic ehrlichiosis following inoculation with the human granulocytotropic ehrlichia was shown to be resistant to challenge with Ehrlichia equi, a closely related agent. This result further substantiates the close and potentially conspecific relationship between these two granulocytotropic ehrlichiae.

Transmission and passage in horses of the agent of human granulocytic ehrlichiosis.

The human granulocytotropic ehrlichia and Ehrlichia equi produce similar diseases in their respective host species (humans, horses). Currently, the phylogenetic and biologic relationships of these 2 uncultured pathogens remain unclear. Previous studies have revealed nucleotide sequence similarity approaching identity at the level of the 16S ribosomal RNA gene.

Double-nested polymerase chain reaction for detection of caprine arthritis-encephalitis virus proviral DNA in blood, milk, and tissues of infected goats.

A nested polymerase chain reaction (PCR) for detecting proviral DNA of caprine arthritis-encephalitis virus (CAEV) in biological samples was developed. Primers for both gag and pol sequences of the CAEV genome were included in a single tube for simultaneous amplification ('double' PCR), and the resulting bands were resolved visually in ethidium bromide-stained agarose gels. Internal gag and pol probes were used to verify the identity of the amplified products by non-radioactive Southern hybridization.

Effects of incidental infections and immune activation on disease progression in experimentally feline immunodeficiency virus-infected cats.

Specific pathogen-free cats were experimentally infected with feline immunodeficiency virus (FIV) and subsequently exposed to common infectious pathogens and immune stimuli over a 3-year period. Cats with preexisting FIV infection showed signs of disease after exposure to Haemobartonella felis, Toxoplasma gondii, feline herpesvirus-1, and feline calicivirus similar to signs in non-FIV-infected cats, although they were more severe. No adverse effects of immunization with inactivated rabies virus vaccine and a synthetic polyproline immunogen were observed in either FIV-infected or non-FIV-infected cats, whereas the application of a diphtheria-tetanus-pertussis vaccine caused transient fever and lymphadenopathy in both groups of animals.

Antiviral studies of feline infectious peritonitis virus in vitro.

Sixteen compounds were tested for their ability to inhibit the replication in vitro of feline infectious peritonitis virus (FIPV), a coronavirus that causes a lethal, immunologically mediated illness in domestic and exotic cats. Six of the compounds, when incubated with cells and titrations of the virus, were found to reduce the virus titres by 0.401 to 0.

Feline immunodeficiency virus infection of cats as a model to test the effect of certain in vitro selection pressures on the infectivity and virulence of resultant lentivirus variants.

Three groups of specific pathogen-free (SPF) domestic cats, each containing 5 animals, were infected with one of three closely related FIV variants and monitored for 36 weeks. A fourth group of 5 cats was sham-infected and served as uninfected controls. FIV variants included: (1) a fully virulent animal passaged FIV-Petaluma; (2) a Crandell feline kidney (CrFK) cell-adapted FIV-Petaluma (FIV-CrFK); and (3) a variant of FIV-CrFK (FIV-CrFKAZT) that had been selected in vitro for resistance to azidothymidine.

Interaction of acute feline herpesvirus-1 and chronic feline immunodeficiency virus infections in experimentally infected specific pathogen free cats.

Cats with or without chronic feline immunodeficiency virus (FIV) infection were exposed to feline herpesvirus, type 1 (FHV-1). FIV infected cats became sicker than non-FIV infected cats and required more supportive treatment. However, there were no differences in the length of their illness or in the levels and duration of FHV-1 shedding.

Detection of feline immunodeficiency virus (FIV) nucleic acids in FIV-seronegative cats.

A study was undertaken to determine the rate of viral transmission among naive specific-pathogen-free (SPF) cats living in close contact with feline immunodeficiency virus (FIV)-infected cats. Twenty SPF cats were housed in the same rooms with experimentally FIV-infected seropositive and virus culture-positive cats for 2 to 4 years and were monitored for the presence of FIV nucleic acids and antibodies. Only 1 of the 20 cats became seropositive and virus culture positive and developed signs of disease.

Progressive immune dysfunction in cats experimentally infected with feline immunodeficiency virus.

Within 6 months of infection with the Petaluma isolate of feline immunodeficiency virus, specific-pathogen-free domestic cats exhibited a decrease in the percentage and number of circulating CD4+ lymphocytes and in the CD4+/CD8+ T-cell ratio, along with a marginally significant depression of pokeweed mitogen-induced lymphocyte proliferation in vitro. There was no loss of responsiveness to concanavalin A during this stage, and the cats were capable of mounting a satisfactory antibody response to a T-dependent, synthetic polypeptide immunogen. The pokeweed mitogen response deficit became clearly demonstrable by 11 to 12 months postinfection.