Nasal DNA-MVA SIV vaccination provides more significant protection from progression to AIDS than a similar intramuscular vaccination.

Preventive human immunodeficiency virus (HIV) vaccination may require induction of virus-specific immune responses at mucosal sites to contain viral infection locally after exposure, as most HIV infections occur through mucosal surfaces. We compared the efficacy of an intranasal or intramuscular Simian immunodeficiency virus (SIV)+ interleukin (IL)-2+IL-15 DNA/SIV-MVA (modified vaccinia virus Ankara) vaccination in preventing disease progression in SIVmac251 intrarectally challenged rhesus macaques. SIV-specific rectal IgA responses were more significantly persistent in nasally vaccinated than in intramuscularly vaccinated animals. No significant differences were observed in the magnitude of systemic T-cell responses between the two groups, although the nasal immunization induced more significant anti-SIV T-cell responses in the colorectal mucosa. After challenge, CD4(+) central memory (C(M)) T-cell preservation and significant disease-delay were observed in both vaccination groups. However, nasally vaccinated animals had more significant early preservation of circulating and colorectal CD4(+) C(M) T cells, of circulating CD4(+)/alpha4beta7(+) effector memory (E(M)) T cells, and a longer disease-free interval when compared with the intramuscularly vaccinated or control groups. Regardless of vaccination status, long-term viremia control and preservation of CD4(+) C(M) T cells was detected in animals with significantly higher systemic CD8(+)/tumor necrosis factor (TNF)-alpha(+) and CD8(+)/interferon (IFN)-gamma(+) T-cell responses and higher SIV-specific CD4(+)/IL-2(+) responses in colorectal T cells.

Rhesus lymphocryptovirus type 1-associated B-cell nasal lymphoma in SIV-infected rhesus macaques.

Epstein-Barr virus (EBV) is a worldwide endemic gamma herpesvirus of the genus Lymphocryptovirus (LCV) that infects more than 90% of the world's population. EBV has been associated with a variety of malignancies, but it has a demonstrated role in lymphomas, especially in immunosuppressed individuals. Lymphomas of the nasal cavity, paranasal sinuses, and nasopharynx are uncommon and constitute less than 5% of all extranodal lymphomas. Sinonasal non-Hodgkin's lymphomas have been reported in patients infected with human immunodeficiency virus (HIV) at an increased frequency. Rhesus LCV (rhLCV), the rhesus viral homolog of EBV, has been cloned and is associated with B-cell lymphomas in immunosuppressed rhesus macaques. We report two cases of B-cell lymphoma within the nasal cavity from 2 simian immunodeficiency virus-infected rhesus macaques with acquired immunodeficiency syndrome. The B-cell phenotype and rhLCV association were demonstrated by immunohistochemistry and confocal microscopy. The majority of the nuclei of the neoplastic B lymphocytes were EBNA-2 positive. RhLCV type 1 sequences were verified from the neoplasms by polymerase chain reaction. Nasal lymphoma is an unusual presentation of rhLCV-associated B-cell lymphoma in immunosuppressed rhesus macaques. These tumors demonstrate comparable viral pathogenesis with EBV-induced nasal lymphomas in HIV-positive people.

Induction of disseminated Mycobacterium avium in simian AIDS is dependent upon simian immunodeficiency virus strain and defective granuloma formation.

Mycobacterium avium complex (MAC) is the most common disseminated bacterial disease in patients infected by the human immunodeficiency virus. Although murine models of disseminated MAC exist, they are primarily based on underlying genetic susceptibilities and cannot adequately address the complex interactions that occur between host, mycobacteria, and immunosuppressive lentivirus. To address this problem we have developed an experimental system to co-inoculate rhesus macaques with the simian immunodeficiency virus (SIV) and a clinical M. avium isolate that results in a disease virtually identical to that observed in human cases. Using this experimental system we have found that the development of disseminated MAC is dependent on viral strain. Animals co-infected with SIVmac251 and M. avium developed progressive disease, whereas control animals and animals inoculated with closely related viruses (SIVmac239 and SIVmac239MER) developed self-limiting infections. The ability of animals infected with SIVmac239 or SIVmac239MER to eliminate mycobacterial disease was independent of viral load and CD4 T-cell number but was correlated with the size and composition of microgranulomas. This work establishes a novel primate model of disseminated MAC in the context of immunosuppressive lentiviral infection and advances our understanding of why human immunodeficiency virus-infected patients are remarkably sensitive to the development of mycobacterial disease.

Enteropathogenic Escherichia coli and ulcerative colitis in cotton-top tamarins (Saguinus oedipus).

The cotton-top tamarin (CTT; Saguinus oedipus) is an endangered New World primate that develops a highly prevalent idiopathic colitis resembling human ulcerative colitis. This study found that enteropathogenic Escherichia coli (EPEC) caused acute colitis in CTTs, which was associated with ulcerative colitis. EPEC clinical isolates revealed localized adherence patterns by HEp-2 assay and were devoid of Shiga-toxin production. Sequencing of the eae gene (GenBank accession no. AF319597) revealed 99.2% identity to sequences of human isolates (GenBank AF116899) and corresponded to the epsilon intimin gene subtype. Detection of intimin sequences by polymerase chain reaction on primary fecal cultures indicated widespread EPEC infection in the CTT colony. Prospective analysis revealed that animals with fecal cultures positive for intimin sequences had a higher frequency of active colitis (75.0% vs. 27.2%; P<.005, chi(2) test) and higher histological scores of colonic inflammation (0.875 vs. 0.455, respectively; P<.05, Mann-Whitney rank sum test).

Identification of enteropathogenic Escherichia coli in simian immunodeficiency virus-infected infant and adult rhesus macaques.

Enteropathogenic Escherichia coli (EPEC) was recognized as a common opportunistic pathogen of simian immunodeficiency virus-infected rhesus macaques (Macaca mulatta) with AIDS. Retrospective analysis revealed that 27 of 96 (28.1%) animals with AIDS had features of EPEC infection, and EPEC was the most frequent pathogen of the gastrointestinal tract identified morphologically. In 7.3% of animals dying with AIDS, EPEC represented the sole opportunistic agent of the gastrointestinal tract at death. In 20.8% of cases, it was seen in combination with one or more gastrointestinal pathogens, including Cryptosporidium parvum, Enterocytozoon bieneusi, Mycobacterium avium, Entamoeba histolytica, Balantidium coli, Strongyloides stercoralis, cytomegalovirus, and adenovirus. Clinically, infection was associated with persistent diarrhea and wasting and was more frequent in animals that died at under 1 year of age (P < 0.001, Fisher exact test). The organism was associated with the characteristic attaching and effacing lesion in colonic tissue sections and produced a focal adherence pattern on a HEp-2 assay but was negative for Shiga toxin production as assessed by PCR and a HeLa cell cytotoxicity assay. A 2.6-kb fragment encompassing the intimin gene was amplified and sequenced and revealed 99.2% identity to sequences obtained from human isolates (GenBank AF116899) corresponding to the epsilon intimin subtype. Further investigations with rhesus macaques may offer opportunities to study the impact of EPEC on AIDS pathogenesis and gastrointestinal dysfunction.

Dynamics of CCR5 expression by CD4(+) T cells in lymphoid tissues during simian immunodeficiency virus infection.

Early viral replication and profound CD4(+) T-cell depletion occur preferentially in intestinal tissues of macaques infected with simian immunodeficiency virus (SIV). Here we show that a much higher percentage of CD4(+) T cells in the intestine express CCR5 compared with those found in the peripheral blood, spleen, or lymph nodes. In addition, the selectivity and extent of the CD4(+) T-cell loss in SIV infection may depend upon these cells coexpressing CCR5 and having a "memory" phenotype (CD45RA(-)). Following intravenous infection with SIVmac251, memory CD4(+) CCR5(+) T cells were selectively eliminated within 14 days in all major lymphoid tissues (intestine, spleen, and lymph nodes). However, the effect on CD4(+) T-cell numbers was most profound in the intestine, where cells of this phenotype predominate. The CD4(+) T cells that remain after 14 days of infection lacked CCR5 and/or were naive (CD45RA(+)). Furthermore, when animals in the terminal stages of SIV infection (with AIDS) were examined, virtually no CCR5-expressing CD4(+) T cells were found in lymphoid tissues, and all of the remaining CD4(+) T cells were naive and coexpressed CXCR4. These findings suggest that chemokine receptor usage determines which cells are targeted for SIV infection and elimination in vivo.

Enterocytozoon bieneusi as a cause of proliferative serositis in simian immunodeficiency virus-infected immunodeficient macaques (Macaca mulatta).

CONTEXT: Enterocytozoon bieneusi is the most frequent microsporidian parasite of human patients with acquired immunodeficiency syndrome and is a significant cause of diarrhea and wasting. Recently, this organism has also been recognized as a spontaneous infection of several species of captive macaques. As in humans, E bieneusi frequently causes enteropathy and cholangiohepatitis in immunodeficient simian immunodeficiency virus (SIV)-infected macaques. OBJECTIVE: To examine E bieneusi as an etiologic agent of nonsuppurative proliferative serositis in immunodeficient rhesus macaques (Macaca mulatta). DESIGN: Retrospective analysis of necropsy material obtained from immunodeficient SIV-infected rhesus macaques. RESULTS: Examination of SIV-infected rhesus macaques (n = 225) revealed E bieneusi proliferative serositis in 7 of 16 cases of peritonitis of unknown origin. The organism could be identified by in situ hybridization and polymerase chain reaction in sections of pleura and peritoneum obtained at necropsy. Serositis was always accompanied by moderate-to-severe infection of the alimentary tract, and morphologic evidence suggested dissemination through efferent lymphatics. Colabeling experiments revealed most infected cells to be cytokeratin positive and less frequently positive for the macrophage marker CD68. Sequencing of a 607-base pair segment of the small subunit ribosomal gene revealed 100% identity to sequences obtained from rhesus macaques (Genbank accession AF023245) and human patients (Genbank accession AF024657 and L16868). CONCLUSIONS: These findings indicate that E bieneusi disseminates in immunodeficient macaques and may be a cause of peritonitis in the immunocompromised host.

Enterocytozoon bieneusi infection in patients without evidence of immunosuppression: two cases from Zimbabwe found to have positive stools by PCR.

Patients infected with human immunodeficiency virus (HIV) often also have intestinal infections with Enterocytozoon bieneusi. Recently, infection with this microsporidian has been described in immunocompetent subjects, mainly from Europe. When the stools of six HIV-negative patients who presented with diarrhoea in Zimbabwe were investigated, using a recently described protocol based on PCR, two patients were found to have E. bieneusi infections. These two individuals presented with a self limited diarrhoea, abdominal cramping and nausea. These data indicate that E. bieneusi may be a more common cause of diarrhoea in Zimbabwe than previously thought. Larger, prospective studies are needed.

Intestinal parasites in patients with diarrhea and human immunodeficiency virus infection in Zimbabwe.

OBJECTIVES: To determine the prevalence of intestinal parasites and risk factors for infection associated with diarrhea in HIV-infected patients in Harare, Zimbabwe. DESIGN: Prospective observational study. METHODS: Single stool samples were collected from 88 HIV-infected individuals presenting with diarrhea of greater than 1 week duration. Stools were examined for intestinal parasites using modified acid fast stain, fluorescence- labeled monoclonal antibody for Cryptosporidium parvum, as well as a modified trichrome stain and a PCR-based protocol for Enterocytozoon bieneusi. RESULTS: C. parvum was detected in 9% (seven out of 82) of samples evaluated, but no Cyclospora was detected. E. bieneusi was detected in 18% (10 out of 55) of stool by trichrome staining and in 51% (28 out of 55) of stool examined by PCR. Risk factors for E. bieneusi infection were: living in rural areas, consumption of nonpiped water, contact with cow dung and household contact with an individual with diarrhea. CONCLUSION: E. bieneusi infection was common in HIV-infected patients with diarrhea in Zimbabwe and may be acquired through person-to-person and fecal-oral transmission.

Transmission and serial propagation of Enterocytozoon bieneusi from humans and Rhesus macaques in gnotobiotic piglets.

For over a decade Enterocytozoon bieneusi infections in people with AIDS have been linked with chronic diarrhea and wasting. The slow scientific progress in treating these infections is attributed to the inability of investigators to cultivate the parasite, which has also precluded evaluation of effective therapies. We report here successful serial transmissions of E. bieneusi from patients with AIDS and from macaques with AIDS to immunosuppressed gnotobiotic piglets. One infected piglet was still excreting spores at necropsy 50 days after an oral challenge. Spores in feces were detected microscopically by trichrome stain and by PCR and within enterocytes by in situ hybridization and immunohistochemistry. E. bieneusi infection induced no symptoms. The development of an animal model for E. bieneusi will open up new opportunities for investigating this parasite.

Ultrastructural morphology of Enterocytozoon bieneusi in biliary epithelium of rhesus macaques (Macaca mulatta).

Enterocytozoon bieneusi is the most common microsporidian parasite found in humans with acquired immunodeficiency syndrome. A nearly identical organism was recently recognized in rhesus macaques (Macaca mulatta). Ultrastructural examination of this microsporidian parasite in biliary epithelium of rhesus macaques reveals characteristics unique to E. bieneusi, including 1) a lack of sporophorus vesicles or pansporoblastic membranes, 2) direct contact of all stages with the host-cell cytoplasm, 3) elongated nuclei present within proliferative and sporogonial stages, 4) late thickening of the sporogonial plasmodium plasmalemma, 5) electron-lucent inclusions present throughout the life cycle, 6) precocious development of electron dense discs before plasmodial division to sporoblasts, and 7) the presence of polar tube doublets within spores and sporoblasts visualized as 5-7 coils in section.

Localization of persistent Enterocytozoon bieneusi infection in normal rhesus macaques (Macaca mulatta) to the hepatobiliary tree.

Enterocytozoon bieneusi is the most common microsporidian parasite recognized in human patients with AIDS. Recently, we identified a virtually identical organism causing a spontaneous infection associated with hepatobiliary and intestinal disease in simian immunodeficiency virus (SIV)-infected macaques. To examine the natural history of the infection, we examined captive rhesus macaques for E. bieneusi by PCR, in situ hybridization, and cytochemical techniques. PCR performed on fecal DNA detected enterocytozoon infection in 22 (16.7%) of 131 normal rhesus macaques (Macaca mulatta), compared to 18 (33.8%) of 53 rhesus macaques experimentally inoculated with SIV. In normal rhesus macaques, persistence of infection was demonstrated for up to 262 days and was usually not associated with clinical signs. In six of seven normal rhesus animals, E. bieneusi was detected by PCR in bile obtained through percutaneous cholecystocentesis but not by in situ hybridization performed on endoscopic biopsies of duodenum and proximal jejunum.

Development and application of genetic probes for detection of Enterocytozoon bieneusi in formalin-fixed stools and in intestinal biopsy specimens from infected patients.

The microsporidium Enterocytozoon bieneusi is closely linked to wasting and diarrhea in a high proportion of individuals with AIDS. However, its relative contribution to disease is uncertain because diagnosis until recently depended on procedures involving endoscopy. A sensitive PCR technique which amplifies a fragment of the small-subunit rRNA gene of E. bieneusi from formalin-fixed stool samples was developed. Of 80 formalin-fixed stool samples collected from 74 Zimbabweans and 6 U.S. patients who were human immunodeficiency virus positive, 50% tested positive for E. bieneusi by PCR, whereas 24% tested positive for E. bieneusi by light microscopy of trichrome-stained fecal smears. In addition, we describe an in situ hybridization technique which detected and identified E. bieneusi as the causative agent in all six intestinal biopsy specimens tested. Both the PCR and in situ hybridization procedures are sensitive diagnostic tools which will complement currently available techniques and enable the differentiation of E. bieneusi from other microsporidia to be made.

Identification of an Enterocytozoon bieneusi-like microsporidian parasite in simian-immunodeficiency-virus-inoculated macaques with hepatobiliary disease.

Enterocytozoon bieneusi is a common opportunistic pathogen of human patients with acquired immune deficiency syndrome (AIDS) causing significant morbidity and mortality. In a retrospective analysis utilizing conventional histochemical techniques, in situ hybridization, polymerase chain reaction, and ultrastructural examination, we identified 18 simian-immunodeficiency-virus-infected macaques (16 Macaca mulatta, 1 M. nemestrina, and 1 M. cyclopis) with Enterocytozoon infection of the hepatobiliary system and small intestine. The organisms were readily identified in the bile ducts and gall bladder by special stains and by in situ hybridization using a probe directed against the small subunit ribosomal RNA of human origin E. bieneusi. Infection of the biliary system was associated with a nonsuppurative and proliferative cholecystitis and choledochitis. Hepatic involvement was characterized by bridging portal fibrosis and nodular hepatocellular regeneration accompanied by marked bile ductular and septal duct hyperplasia. Ultrastructurally, all developmental stages of the organism were found in direct contact with the host cell cytoplasm; spores and sporoblasts contained a double layer of polar tubes. Sequencing of a 607-bp segment of the small subunit ribosomal RNA revealed 97 and 100% identity to two clones of small subunit ribosomal RNA derived from E. bieneusi of human origin. Extensive morphological and genetic similarities between the simian and human enterocytozoons suggest that experimentally infected macaques may serve as a useful model of microsporidial infection in AIDS.

Transmission and establishment of a persistent infection of Enterocytozoon bieneusi, derived from a human with AIDS, in simian immunodeficiency virus-infected rhesus monkeys.

Enterocytozoon bieneusi is closely linked with chronic diarrhea and wasting in AIDS. Although reported >10 years ago, little is known about the infection and the disease it induces in humans. Duodenal E. bieneusi spores from an AIDS patient were orally transmitted to 2 simian immunodeficiency virus-infected rhesus monkeys. Both animals began shedding spores within a week of inoculation, as confirmed by microscopy and polymerase chain reaction, and continued until euthanatized 7 and 8 months later. E. bieneusi infection in the gut was sparse, either because of moderate numbers of circulating CD4 cells or because monkeys are less susceptible than humans to this infection. This is apparently the first documented transmission of E. bieneusi infection between hosts.

Detection of African horse sickness virus by reverse transcription-PCR.

Reverse transcription-PCR (RT-PCR) was used to detect African horse sickness virus (AHSV). A single primer pair which amplified a 423-bp fragment of the S8 gene which encodes the NS2 protein of AHSV was identified. Amplification of this fragment from all nine serotypes of AHSV was achieved with these primers. Between 10(1) and 10(2) copies of AHSV genomic double-stranded RNA could be detected by RT-PCR followed by agarose gel electrophoresis and ethidium bromide staining. Application of RT-PCR to blood samples from AHSV-infected horses resulted in earlier detection of viremia than virus isolation did. Furthermore, viremia was detected by RT-PCR in blood samples from horses infected with an avirulent isolate of AHSV which were negative by virus isolation. AHSV was also detected by RT-PCR in spleen and lung samples from horses which died of AHSV infection. These results indicate that RT-PCR is a rapid and sensitive method for the identification of horses infected with AHSV.