Biomedical subjects

M E Olson

Publications and source records attributed to M E Olson.

At least 19 recordsLinked to original sources

PubMed2006

Skin wound healing in the first generation (F1) offspring of Yorkshire and red Duroc pigs: evidence for genetic inheritance of wound phenotype.

Fibroproliferative scars in humans often demonstrate familial inheritance patterns, and genetics may contribute to healing and scarring. Genetic factors may also influence the scarring phenotype in a porcine model. Healing of full thickness excisional skin wounds in Yorkshire pigs closely resembles normal healing in humans, while identical wounds in red Duroc pigs form hypercontracted, hyperpigmented scars. The present study has evaluated the healing process in the first generation cross (F1) of red Duroc and Yorkshire pigs. Gross and histologic analysis revealed that the F1 animals exhibit an intermediate healing phenotype, with some features of each parent breed. F1 full thickness wounds were significantly hypercontracted and fibrotic, but apigmented. Analysis of mRNA expression patterns for a panel of relevant molecules (N=32) in the F1 animals revealed some similarities to each parent breed, as well as unique patterns for other molecules. Furthermore, a depth dependency to the healing response was observed at the gross, histologic, and molecular levels, with deep dermal wounds healing similar to Yorkshire wounds. These findings suggest that the genetic contribution to scar phenotype in this animal model is complex. However, the results indicate that further understanding in this model may provide insights into risk factors for hypertrophic scarring in human burn patients.

Animals↗

PubMed2006

Adherence of Staphylococcus epidermidis to biomaterials is augmented by PIA.

Staphylococcus epidermidis is the most common cause of orthopaedic prosthetic device infections. Polysaccharide intercellular adhesin (PIA) is important in the pathogenesis of intravascular catheter-associated infection, and has an essential role in cellular aggregation and biofilm formation. However, the role of PIA in orthopaedic infections is less well understood. We used genetically defined strains of S. epidermidis in an in vitro adherence assay to assess the importance of PIA in the adherence to various orthopaedic biomaterials. On all biomaterials tested (zirconia, ultra-high molecular weight polyethylene, polymethylmethacrylate, cobalt chromium, titanium, stainless steel, and silastic), PIA-positive S. epidermidis 1457 exhibited greater levels of adherence thanS. epidermidis 1457 M10, an isogenic icaA Tn917 mutant. PIA appears to play a critical role in the adherence of S. epidermidis to orthopaedic biomaterials, and may serve as an important virulence determinant in orthopaedic prosthetic device infections.

Bacterial Adhesion↗

PubMed2006

Temporal prevalence of antimicrobial resistance in Campylobacter spp. from beef cattle in Alberta feedlots.

Antimicrobial resistance (AMR) was temporally assessed in campylobacters isolated from beef cattle (7,738 fecal samples from 2,622 animals) in four commercial feedlots in Alberta. All calves were administered chlortetracycline and oxytetracycline in feed, and a majority of the animals (93%) were injected with long-acting oxytetracycline upon arrival at the feedlot. Fecal samples from individual animals were collected upon arrival (i.e., entry sample), 69 days (standard deviation [SD] = 3 days) after arrival (i.e., interim sample), and 189 days (SD = 33 days) after arrival (i.e., exit sample) at the feedlot. In total, 1,586 Campylobacter isolates consisting of Campylobacter coli (n = 154), Campylobacter fetus (n = 994), Campylobacter jejuni (n = 431), Campylobacter hyointestinalis (n = 4), and Campylobacter lanienae (n = 3) were recovered and characterized. The administration of antimicrobials did not decrease carriage rates of campylobacters, and minimal resistance (< or =4%) to azithromycin, ciprofloxacin, enrofloxacin, gentamicin, and meropenem was observed. In contrast, substantive increases in the prevalence of isolates resistant to tetracycline and doxycycline (56 to 89%) for C. coli, C. fetus, and C. jejuni, as well as in the number of animals (7 to 42%) from which resistant isolates were recovered, were observed during the feedlot period. Increased resistance to erythromycin (total isolates and carriages rates) was also observed in isolates of C. coli over the three isolation times. The majority of C. fetus isolates recovered were resistant to nalidixic acid, but this was independent of when they were isolated. A relatively limited number of multidrug-resistant isolates were recovered and consisted primarily of C. coli resistant to tetracyclines and erythromycin (10% of isolates). Over the course of the feedlot period, considerable increases in antimicrobial resistance were observed in C. coli, C. fetus, and C. jejuni, but with the exception of erythromycin resistance in C. coli, the administration of antimicrobial agents to beef cattle was found to have a minimal impact on resistance to macrolides and fluoroquinolones, the two classes of antimicrobials used to treat campylobacteriosis in humans. However, the widespread use of antimicrobial agents in beef production and the possible horizontal transfer of mobile genetic elements with antimicrobial resistance determinants among Campylobacter and other bacterial taxa emphasize the need to monitor AMR development in bacteria from beef cattle.

Alberta↗

PubMed2005

Molecular and morphological characterization of Echinococcus in cervids from North America.

Many issues concerning the taxonomy of Echinococcus have been resolved in recent years with the application of molecular tools. However, the status of Echinococcus maintained in transmission cycles involving cervid intermediate hosts remains to be determined. The recent characterization of the parasite from cervids in Finland has highlighted the paucity of data available, particularly that from North America. In this study, we have characterized a large number of Echinococcus isolates from cervids from Western Canada on the basis of morphology and molecular genetic techniques. Our results support earlier studies suggesting that Echinococcus of cervid origin is phenotypically and genetically distinct to Echinococcus maintained in domestic host assemblages, and also confirms that Echinococcus of cervid origin does not constitute a genetically homogeneous group. However, our data do not support the existence of 2 distinct genotypes (strains/subspecies) with separate geographical distributions. Our data appear to support the existence of only 1 species in cervids, but additional isolates from cervids and wolves in other endemic regions should be characterized before a final decision is made on the taxonomic status of Echinococcus in cervids.

Adenosine Triphosphate↗

PubMed2005

Individual intake and antiparasitic efficacy of free choice mineral containing fenbendazole for grazing steers.

A 95-day study (June 25-September 27, 2001) was conducted using 120 steers (311.9+/-2.4 kg) randomly allocated to two treatments: (1) mineral containing 0.55% fenbendazole (FBZ) and (2) control, no FBZ in the mineral. Animals in the FBZ group were individually identified by an electronic tag that was read each time an animal attended the mineral feeder. The feeder was equipped with load cells that enabled individual mineral intakes to be estimated. The FBZ group was provided with non-medicated mineral during a 14-day adaptation period (July 23-August 5) and an 8-day post-medication period (September 17-24). The intake of FBZ was monitored for 14 days during each of the two treatment periods; August 6-19 and September 3-16, separated by a 14-day non-medicated period, August 20-September 2. Control animals had access to non-medicated mineral for the entire 95-day study period. All steers were grazed on alfalfa-grass pasture for the duration of the study and had free access to flocculated, filtered and chlorinated water via an automatic waterer. Fecal samples were collected from steers three times during the experiment July 23, August 27 and September 27, and analyzed for nematode eggs and Giardia sp. cysts. Seventy-five and 83% of the steers in the FBZ group visited the mineral feeder during the first and second treatment periods, respectively. Individual daily mineral and FBZ intake for the first and second treatment periods was 52.9+/-6.6g per day and 10.1+/-1.2mg/kg BW; 72.3+/-8.4 g per day and 11.8+/-1.4 mg/kg BW, respectively. FBZ animals were separated into three groups during each treatment period based on the recommended dose (RD) of FBZ (5 mg/kg/BW), those that received > the RD, those that received < RD but > 50% RD and those that received < 50% of RD. Nematode egg counts and the number of animals infected with nematodes was reduced (p < 0.05) in all cattle that consumed FBZ as compared to control animals. In contrast to nematode eggs, numbers of Giardia cysts was not reduced (p > 0.05) by FBZ as compared to controls in either treatment period. These results may be a reflection of Giardia re-infection occurring following treatment and highlight the need for variation in treatment regimes specifically targeted at the parasite of interest.

Administration, Oral↗

PubMed2005

Cryptosporidium and cryptosporidiosis.

Cryptosporidium is one of the most common enteric protozoan parasites of vertebrates with a wide host range that includes humans and domestic animals. It is a significant cause of diarrhoeal disease and an ubiquitous contaminant of water which serves as an excellent vehicle for transmission. A better understanding of the development and life cycle of Cryptosporidium, and new insights into its phylogenetic relationships, have illustrated the need to re-evaluate many aspects of the biology of Cryptosporidium. This has been reinforced by information obtained from the recent successful Cryptosporidium genome sequencing project, which has emphasised the uniqueness of this organism in terms of its parasite life style and evolutionary biology. This chapter provides an up to date review of the biology, biochemistry and host parasite relationships of Cryptosporidium.

Animals↗

PubMed2005

Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis.

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of Campylobacter species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.

Animals↗

PubMed2004

Genome diversity among regional populations of Francisella tularensis subspecies tularensis and Francisella tularensis subspecies holarctica isolated from the US.

Francisella tularensis is a highly infectious facultative intracellular pathogen that is considered a potential agent of bioterrorism. Four different F. tularensis subspecies have been identified and they appear to display different ecological and virulence characteristics as well as differences in geographical distribution. One simple explanation for the variation in ecological and virulence characteristics is that they are conferred by differences in genome content. To characterize genome content among stains isolated from United States, we have used a DNA microarray designed from a shotgun library of a reference strain. Polymorphisms distributed among polyphyletic sets of strains was the most common pattern of genome alteration observed, indicating that strain-specific genome variability is significant. Nonetheless, 13 different contiguous segments of the genome were found to be missing exclusively in each of the subsp. holarctica strains tested. All 13 are associated with repeat sequences or transposases that could promote insertion/deletion events. Comparison of the live vaccine strain to other holarctica strains also identified three regions that are absent exclusively in the live vaccine strain derived from holarctica.

Bacterial Vaccines↗

PubMed2004

Complete development of Cryptosporidium parvum in host cell-free culture.

The present study describes the complete in vitro development of Cryptosporidium parvum (cattle genotype) in RPMI-1640 maintenance medium devoid of host cells. This represents the first report in which Cryptosporidium is shown to multiply, develop and complete its life cycle without the need for host cells. Furthermore, cultivation of Cryptosporidium in diphasic medium consisting of a coagulated new born calf serum base overlaid with maintenance medium greatly increased the total number of Cryptosporidium stages. Type I and II meronts were detected giving rise to two morphologically different merozoites. Type I meronts, which appear as grape-like clusters as early as 48 h post culture inoculation, release merozoites, which are actively motile, and circular to oval in shape. Type II meronts group in a rosette-like pattern and could not be detected until day 3 of culturing. Most of the merozoites released from type II meronts are generally spindle-shaped with pointed ends, while others are rounded or pleomorphic. In contrast to type I, merozoites from type II meronts are less active and larger in size. Sexual stages (micro and macrogamonts) were observed within 6-7 days of culturing. Microgamonts were darker than macrogamonts, with developing microgametes, which could be seen accumulating at the periphery. Macrogamonts have a characteristic peripheral nucleus and smooth outer surface. Oocysts at different levels of sporulation were seen 8 days post culture inoculation. Cultures were terminated after 4 months when the C. parvum life cycle was still being perpetuated with the presence of large numbers of excysting and intact oocysts. Culture-derived oocysts obtained after 46 days p.i. were infective to 7- to 8-day-old ARC/Swiss mice. The impact of C. parvum developing in cell-free culture is very significant and will facilitate many aspects of Cryptosporidium research.

Animals↗

PubMed2004

DNA sequence analysis of regions surrounding blaCMY-2 from multiple Salmonella plasmid backbones.

The emergence in the United States of resistance to expanded-spectrum cephalosporin (e.g., ceftriaxone) within the salmonellae has been associated primarily with three large (>100-kb) plasmids (designated types A, B, and C) and one 10.1-kb plasmid (type D) that carry the blaCMY-2 gene. In the present study, the distribution of these four known blaCMY-2-carrying plasmids among 35 ceftriaxone-resistant Salmonella isolates obtained from 1998 to 2001 was examined. Twenty-three of these isolates were Salmonella enterica serotype Newport, 10 were Salmonella enterica serotype Typhimurium, 1 was Salmonella enterica serotype Agona, and 1 was Salmonella enterica serotype Reading. All 23 serotype Newport isolates carried a type C plasmid, and 5, 4, and 1 serovar Typhimurium isolate carried type B, A, and C plasmids, respectively. Both the serotype Agona and serotype Reading isolates carried type A plasmids. None of the isolates carried a type D plasmid. Hybridization data suggested that plasmid types A and C were highly related replicons. DNA sequencing revealed that the region surrounding blaCMY-2 was highly conserved in all three plasmid types analyzed (types B, C, and D) and was related to a region surrounding blaCMY-5 from the Klebsiella oxytoca plasmid pTKH11. These findings are consistent with a model in which blaCMY-2 has been disseminated primarily through plasmid transfer, and not by mobilization of the gene itself, to multiple Salmonella chromosomal backbones.

Bacterial Typing Techniques↗

PubMed2003

Biology of Cryptosporidium parvum in pigs: from weaning to market.

Cryptosporidium parvum is commonly identified as infecting domestic livestock and humans. Prevalence of C. parvum in pigs has been reported, however, the duration and infection pattern of naturally acquired Cryptosporidium infections in pigs has not been reported. This study was undertaken to investigate the age of oocyst shedding and duration of natural Cryptosporidium parvum infections in pigs from weaning to market weight. Fecal samples were collected from weaned Yorkshire-Landrace piglets (n=33) twice per week until Cryptosporidium oocysts were detected. Upon oocyst detection, fecal samples were collected three times per week and pigs were monitored throughout the study for diarrhea and examined after concentration and immunofluroescent staining. Cryptosporidium isolates were genotyped by polymerase chain reaction to amplify the HSP70 gene which was subsequently sequence analyzed. All 33 pigs shed oocysts some time during the study. The mean age of initial oocyst detection was 45.2 days post-weaning with the mean duration of infection 28.7 days. Mean number of Cryptosporidium oocysts was low and declined to zero prior to study completion. Episodes of diarrhea were not associated with oocyst excretion. Genetic sequences were obtained for 10 of the pigs. All of the 10 isolates aligned as the Cryptosporidium parvum 'pig' genotype. This study demonstrates that the age and duration of oocyst shedding in pigs infected with C. parvum porcine genotype is different from other livestock species.

Aging↗

PubMed2003

Prevalence and genotyping of Giardia duodenalis from beef calves in Alberta, Canada.

Giardia infections in domestic cattle has come under increasing scrutiny owing to the potential contamination of surface and ground waters through manure distribution on fields and pasture runoff. The objective of the study was to determine the prevalence and genotypes of Giardia duodenalis in beef calves in major beef cow calf farms in Alberta, Canada. Fecal samples were collected from beef calves aged 2-10 weeks at nine farms in Alberta. Samples were examined for the presence of G. duodenalis cysts by immunofluorescent staining. Giardia cysts were found in 168 of the 495 fecal samples examined, with prevalence ranging from 7 to 60% among farms. Genotypic analysis of positive isolates utilizing PCR and sequencing of a 292 bp fragment of the 16S-rRNA locus, revealed the hoofed livestock genotype in 41 of the 42 isolates. One isolate was identical to the Assemblage A genotype. The results of this study demonstrate that beef calves in this area are primarily infected with the livestock genotype which is thought to be specific to artiodactyl hosts and non-infective to humans. This suggests that the Giardia carried by beef cattle may be a minimal zoonotic threat.

Alberta↗

PubMed2003

Giardia duodenalis trophozoites isolated from a parrot (Cacatua galerita) colonize the small intestinal tracts of domestic kittens and lambs.

This study examines the ability of Giardia duodenalis trophozoites, isolated from a wild bird, to colonize the intestinal tracts of companion animals (kittens) and domestic ruminants (lambs). Trophozoites colonized the intestinal tracts of intraduodenally inoculated animals as demonstrated by increasing parasite burdens within the duodenum and jejunum and by fecal passage of cysts within 4 days post-inoculation. The pathogenesis of the trophozoites was further investigated in kittens. In these animals, infection significantly reduced jejunal brush border microvillous length and density, which resulted in a loss of overall epithelial brush border surface area. This injury was associated with the production of diarrhea in four of five infected kittens. These findings indicate that some bird species may carry G. duodenalis that represent a possible health threat to companion animals and livestock. Our results describe the first successful colonization of avian-derived G. duodenalis trophozoites in the small intestines of domestic kittens and lambs.

Animals↗

PubMed2003

Transfer of a rifampicin-resistant Escherichia coli strain among feedlot cattle.

AIMS: To determine the incidence of transfer of a naturally occurring rifampicin-resistant strain of Escherichia coli (RREC) among cattle in a research feedlot. METHODS AND RESULTS: During three separate experiments, steers in three different pens were orally inoculated with RREC originally isolated from bovine faeces. Faecal swabs were performed on all steers in the feedlot at approximately 5 week intervals thereafter. Faecal grab samples were collected from steers in the inoculated and the immediately adjacent pens for up to 4 months. In all three experiments, the inoculated steers and penmates shed RREC within 48 h, and then shed intermittently throughout the sampling periods. Transfer of RREC to steers in an adjacent pen was confirmed only during the first experiment, but never to those in non-adjacent pens. All recovered RREC isolates were compared with the inoculated strain using multiple methods indicating that all RREC isolates were descendants of the original inoculated strain. CONCLUSIONS: Detection of the RREC strain on the pen floor and within the animal handling system, but not in the feed troughs or water bowls, suggests faecal-oral to be the primary mode of transmission among animals. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that in the absence of selective pressure, antibiotic-resistant bacteria may persist in cattle for a short duration but widespread transfer among cattle in a feedlot environment may be an exception rather than the norm. Modifications to feedlot management are discussed.

Animal Feed↗

PubMed2002

Successful in vitro cultivation of Cryptosporidium andersoni: evidence for the existence of novel extracellular stages in the life cycle and implications for the classification of Cryptosporidium.

The present study describes the complete development of all life cycle stages of Cryptosporidium andersoni in the HCT-8 cell line. The in vitro cultivation protocols were the same as those used for the successful growth of all life cycle stages of Cryptosporidium parvum (Int. J. Parasitol. 31 (2001) 1048). Under these culture conditions, C. andersoni grew and proliferated rapidly with the completion of the entire life cycle within 72h post-infection. The developmental stages of C. andersoni are larger than those of C. parvum enabling easier identification of life cycle stages including a previously unrecognised extracellular stage. The presence of this extracellular stage was further confirmed following its isolation from the faeces of infected cattle using a laser microdissection technique. This stage was present in large numbers and some of them were seen undergoing syzgy. Extraction of DNA from the extracellular stage, followed by polymerase chain reaction-restriction fragment length polymorphism and sequencing of the 18S rDNA confirmed that this is a stage in the life cycle of C. andersoni. In vitro, extracellular stages were always observed moving over the HCT-8 cells infected with C. andersoni. Comparative observations with C. parvum also confirmed the presence of extracellular stages. Extracellular stages were recovered from in vitro culture after 5 days post-infection with the cattle genotype of C. parvum and from infected mice. At least two morphologically different stages (stages one and two) were purified from mice after 72h of infection. The presence and morphological characterisation of extracellular developmental stages in the life cycle of Cryptosporidium confirms its relationship to gregarines and provides important implications for our understanding of the taxonomic and phylogenetic affinities of the genus Cryptosporidium. The growth of C. andersoni in cell culture now provides a means of studying its development, metabolism, and behaviour as well as testing its response to different therapeutic agents.

Animals↗

PubMed2002

Prevalence of Giardia and Cryptosporidium and characterization of Cryptosporidium spp. isolated from wildlife, human, and agricultural sources in the North Saskatchewan River Basin in Alberta, Canada.

The environmental distribution of Giardia spp. and Cryptosporidium spp. is dependent upon human, agricultural, and wildlife sources. The significance of each source with regard to the presence of parasites in the environment is unknown. This 2-year study examined parasite prevalence in human sewage influent, wildlife, and agricultural sources associated with the North Saskatchewan River Basin in Alberta, Canada. Fecal samples were collected from cow-calf, dairy, and hog operations in the watershed area. Sewage-treatment facilities were sampled bimonthly during the 2-year study, and wildlife scat was collected at locations along tributaries of the North Saskatchewan River. All samples were analyzed for the presence of Giardia and Cryptosporidium, using sucrose-gradient separation followed by immunofluorescent microscopy. Giardia and Cryptosporidium were detected in all three sources. The lowest prevalence of both Giardia (3.28%) and Cryptosporidium (0.94%) was found in wildlife, with 6 of 19 species testing positive. Sewage influent had the highest prevalence of Giardia (48.80%) and Cryptosporidium parvum-like oocysts (5.42%); however, the concentration of both parasites was minimal compared with the concentration detected in cattle feces. Cow-calf sources contained the highest concentration of Giardia (mean 5800/g feces, P < 0.01), and dairy sources contained the highest concentration of C. parvum-like oocysts (mean 295/g feces, P < 0.01). Although prevalence and concentration are higher in cattle feces than in sewage, the Giardia and Cryptosporidium in animal manure do not have direct access to water draining into the North Saskatchewan River. PCR-based characterization of rDNA from isolates of Cryptosporidium collected from Alberta human, pig, calf, mature steer, dog, cat, and beaver hosts revealed distinct genetic differences that may reflect host specificity.

Animals↗

PubMed2001

Characterization of biofilm growth and biocide susceptibility testing of Mycobacterium phlei using the MBEC assay system.

The importance of non-tuberculosis mycobacterial biofilm species in medicine, industry and the environment has recently gained attention. Our objectives were to characterize biofilm growth of Mycobacterium phlei M4, as a model of rapidly growing mycobacteria using the minimal biofilm eradication concentration (MBEC) and to compare biocide susceptibility of planktonic and biofilm organisms. Scanning electron microscopy was also carried out to observe biofilm morphology. With the exception of Sporicidin and Virkon the minimum bactericidal concentration values for all biocides tested were lower than the MBEC values. The MBEC assay system was seen to produce multiple and reproducible biofilms of M. phlei and to be a useful tool for susceptibility studies.

Anti-Bacterial Agents↗

PubMed2001

Xenoinfection of nonhuman primates by feline immunodeficiency virus.

New viral infections in humans usually result from viruses that have been transmitted from other species as zoonoses. For example, it is accepted widely that human immunodeficiency virus (HIV) is the result of the propagation and adaptation of a simian immunodeficiency virus (SIV) from nonhuman primates to man [1]. Previously, we reported productive infection of primary human cells in vitro by feline immunodeficiency virus (FIV) [2], a lentivirus that causes an immunodeficiency syndrome in cats similar to HIV in humans [3]. The present study extends these findings by demonstrating that cynomolgus macaques (Macaca fasicularis) infected with FIV exhibited clinical signs, including depletion of CD4+ cells and weight loss, that are consistent with FIV infection. The development of an antibody response to FIV gag-encoded proteins and detection of virus-specific sequences in sera, blood-derived cells, and necropsied tissue accompanied these changes. Moreover, the reactivation of FIV replication from latently infected cells was observed after stimulation in vitro with phorbol esters and in vivo with tetanus toxoid. The proposed use of lentiviruses in human gene therapy [4, 5] and of nonhuman cells and organs in xenotransplantation [6] has raised concerns about zoonoses as potential sources of new human pathogens. Therefore, the study of FIV infection of primate cells may provide insight into the principles underlying retroviral xenoinfections.

Animals↗