Response of colostrum-deprived cynomolgus monkeys to intragastric challenge exposure with simian rotavirus strain SA11

The infectivity and pathogenic potential of a cell culture-adapted simian rotavirus was evaluated in colostrum-deprived newborn and infant cynomolgus macaques (Macaca fascicularis). Intragastric challenge exposure with the simian rotavirus strain SA11 on postpartum day 2 induced diarrhea in 5 of 5 colostrum-deprived newborn monkeys. Compared with sham-inoculated controls, 3 of the 5 inoculated monkeys also manifested reduced body weight gain during the initial 5 days after challenge exposure. Rotavirus was detected in feces of 3 challenge-exposed monkeys for up to 2 days after inoculation. Evaluation of antibody response after rotavirus inoculation was obscured by high but variable prechallenge-exposure serum titers of rotavirus-specific antibody. Preexisting serum titer of neutralizing antibody in newborn monkeys was not predictive of clinical response to inoculation with rotavirus SA11. Two 90-day-old infant monkeys with low serum neutralizing antibody titer did not have diarrhea, reduced weight gain, or antibody response after oral inoculation with rotavirus SA11. Results of these challenge-exposure studies in newborn cynomolgus monkeys were consistent with a heterologous host-rotavirus model and indicate that neonatal serum antibody of maternal origin may not be associated with resistance to rotavirus-induced disease.

[Virus persistence in hepatitis A in monkeys]

A long-term complex observation of 16 cynomolgus monkeys (Macaca fascicularis) and 8 African green monkeys (Cercopithecus aethiops) with spontaneous and experimental hepatitis A revealed two forms of the illness: acute and chronic. Some monkeys developed undulating chronic course of the disease consisting of 2-6 waves. Others developed relapses (1 to 3) which occurred within 2-4 or 6-11.5 months of the infection. The morphological changes in the liver persisted for 7-28 months. Alaninaminotransferase elevations in the blood and HAV shedding in feces were observed periodically for 7-20 months. HAV persistence was documented by radioimmunoassay, enzyme immunoassay, immune electron microscopy and molecular hybridization. Persisting HAV was shown to remain pathogenic for monkeys. Virological evidence of the etiological association of HAV with chronic infection and late relapses has been obtained for the first time.

Baboon T cell lymphomas expressing the B cell-associated surface proteins CD40 and Bgp95

Papio hamadryas baboons in the Sukhumi colony develop enzootic outbreaks of malignant lymphomas with an incidence of about 1.5% per year among adults of the high-risk stock. We investigated the surface phenotypes of cells from normal and lymphomatous animals using antibodies against human lymphocyte antigens. We found that more than 80% of the lymphomas that developed during the last 3 years were characterized histologically to be of the peripheral T cell type. Generally, the lymphomatous cells also expressed high levels of MHC class II DR protein, CD18 (LFA-1 beta chain), and CD45RO. Surprisingly, these cells also expressed on their surface two proteins previously characterized as being relatively B cell-restricted: CD40 and Bgp95. These proteins were never found on the peripheral blood T cells from normal animals. The expression of these two gene products was confirmed by RNA blotting and immunoprecipitation. In most cases, the two B cell-associated proteins were expressed on the predominant T cell subsets; we found both B cell proteins on CD4+, CD8+ as well as on the CD4/8 double-positive cells when these subsets were expressed at high levels. About 90% of these animals are seropositive for Herpesvirus papio and human T cell leukemia virus-1 (HTLV-1) before developing outright lymphomas. In all of the lymphoma samples, HTLV-1 tax DNA sequences were detected by PCR amplification. Whether or not HTLV-1 or the Herpesvirus papio gene products influence the surface expression of CD40 and Bgp95 remains to be determined.

Serologic confirmation of simian T-lymphotropic virus type I infection by using immunoassays developed for human T-lymphotropic virus antibody detection

Serum specimens from diverse species of Old World monkeys, categorized as seropositive (n = 97) or seronegative (n = 23) for human T-lymphotropic virus (HTLV) infection, were tested by using recombinant env-spiked Western immunoblot assays and synthetic peptide assays for simultaneous detection and discrimination of simian T-lymphotropic virus (STLV) infection. Of the 97 seropositive specimens, 93 reacted with the recombinant transmembrane (r21env) protein and 90 reacted with a recombinant, MTA-1, derived from the central region of the external glycoprotein of HTLV-I (rgp46env), thus yielding test sensitivities of 96 and 93%, respectively. While 1 of the 23 negative monkey specimens reacted with r21env, none reacted with rgp46env, for overall specificities of 96 and 100%, respectively. Analysis of synthetic peptide-based immunoassays demonstrated that while 85 of 97 (88%) seropositive specimens reacted with HTLV-I-specific epitope (p19gag), none of the specimens reacted with HTLV-II-specific epitope (gp52env). These results show that recombinant envelope-spiked Western blots provide a simple means for serologic confirmation of STLV-I infection and that type-specific synthetic peptides can be used to confirm the virus type in seropositive monkey specimens.

Activation of B virus (Herpesvirus simiae) in chronically immunosuppressed cynomolgus monkeys

Three of 14 cynomolgus monkeys given the highest dose of an immunosuppressive drug in a 6-month toxicology study developed B virus (Herpesvirus simiae) oral lesions after 3 months of dosing. This necessitated early removal of all high-dose monkeys from the study due to concerns related to B virus. The incidence and severity of parasitic (Oesphagostomum sp.) lesions of the large intestine were also increased in high-dose animals. Both B virus and Oesophagostomum are enzootic in macaques, and the lesions caused by them were considered secondary to chronic immunosuppression caused by the highest dose of the test compound. Evidence of immunosuppression included decreased lymphocyte counts (B-cells; CD2 and CD8 T-cells), histopathologic evidence of lymphoid suppression, and serum-induced inhibition of lymphocyte mitogen responses. Pathogenesis of the B virus was apparently associated with both activation of latent virus as well as transmission of active virus. Approaches for virologic monitoring of primates and for ensuring optimal safety for primate handlers are discussed.

Evidence for occurrence of filovirus antibodies in humans and imported monkeys: do subclinical filovirus infections occur worldwide?

In the present serological study 120 monkey sera from different species originating from the Philippines, China, Uganda and undetermined sources and several groups of human sera comprising a total of 1288 specimens from people living in Germany were examined for the presence of antibodies directed against filoviruses (Marburg virus, strain Musoke/Ebola virus, subtype Zaire, strain Mayinga/Reston virus). Sera were screened using a filovirus-specific enzyme-linked immunosorbent assay (ELISA). ELISA-positive sera were then confirmed by the indirect immunofluorescence technique, Western blot technique, and a blocking assay, and declared positive when at least one confirmation test was reactive. Altogether 43.3% of the monkey sera and 6.9% of the human sera reacted positively with at least one of the three different filovirus antigens. The blocking assays show that antibodies, detected in the sera, are directed to specific filovirus antigens and not caused by antigenic cross-reactivity with hitherto unknown agents. Data presented in this report suggest that subclinical filovirus infections may also occur in humans and in subhuman primates. They further suggest that filoviruses are not restricted to the African continent.

Susceptibility of owl monkeys to Plasmodium falciparum in relation to hemoglobin and karyotype

Humans with inherited abnormalities of hemoglobin (Hb) synthesis have less frequent and less severe infections of malaria. This study sought to determine if karyotypic variation in the owl monkey was expressed as differences in Hb moieties and if it offered a selective advantage in susceptibility to malaria. Five karyotypes of owl monkey were evaluated on the basis of the electrophoretic mobility of their major and minor Hb components. The results of 40 owl monkeys of different karyotypes demonstrated that statistically significant differences exist among karyotype I animals and those with karyotypes II, III, and V, particularly with regard to their HbA2 concentrations. This finding is of interest in light of the fact that karyotype I animals are considered to be less susceptible to infection with human strains of Plasmodium falciparum than karyotypes II, III, and V, which are viewed as being highly susceptible.

Possible influence of measles virus infection of cynomolgus monkeys on the outcome of the neurovirulence test for oral poliovirus vaccine

Macaque monkeys are susceptible to measles infection which triggers temporary immuno-depression similar to the well known phenomenon in humans. It is known that feral monkeys become infected with measles virus when they are exposed to humans. Since Macaca mulatta and M. fascicularis are species used to assay the neurovirulence of oral poliovirus vaccine, the immunodepression caused by measles infection of the test monkeys could significantly alter the results of the neurovirulence test. The serum titers of measles-neutralizing antibodies were studied in over 1500 monkeys used for neurovirulence tests. A high proportion of the feral monkeys had measles antibodies (51-100%); in contrast, none of 493 M. fascicularis monkeys which had been bred in a primate colony under strict isolation measures was found positive for measles antibodies. An increase in the prevalence of measles in the population of Ontario and Quebec provinces was accompanied with an increase in the proportion of measles-positive monkey and their serum antibody titers were found higher. It was observed that monkeys used in tests that had been performed during high measles prevalence presented with a poliomyelitis of more pronounced severity clinically and histologically. The analysis of 29 tests conducted on type 1 vaccines over several years showed a positive correlation (correlation coefficient = 0.5141, P less than 0.0022) between severity of poliomyelitis and the presence of measles serum antibodies in test monkeys (some animals seroconverted during the test). A similar observation, when type 3 Sabin vaccines were tested in M. fascicularis, was recently reported from another laboratory in Ontario.

[The biochemical indices of the blood serum in experimental hepatitis A in tamarins]

Serum biochemical parameters were studied in 42 healthy wild-caught adult tamarins (S. mystax), males and females, to determine the normal values. Blood samples were drawn repeatedly, and the serum was tested for aspartate aminotransferase, alanine aminotransferase, isocitric dehydrogenase, serum glucose, serum urea, triglyceride, cholesterol, albumin, and total protein. The results indicated that serum chemistry values were similar to those reported as normal for both humans and other Callitrichidae species. The study of serum biochemical parameters in tamarins with experimental hepatitis A indicated that serum enzyme activities alone reflected the hepatic damage, while other biochemical parameters were of no real clinical importance. The experimental results showed the levels of serum urea to be indicative of the pathological involvement of the kidneys in experimental hepatitis A in some cases.

Immune responses against sexual stages of Plasmodium vivax during human malarial infections in Sri Lanka

During natural infections of P. vivax malaria a variety of immune responses to the infection affect infectivity of the parasites to mosquitoes. Sexual stage antigens present in the blood stage parasites induce antibodies which may either enhance or suppress the infectivity of the sexual parasites to mosquitoes. Subsequent infections of P. vivax do not, unless occurring within less than 4 months, boost this response indicating a very short immune memory for the relevant antigens. Blood infection also results in the release of cytokines and other non-antibody factors which together can mediate death of the blood stage sexual parasites. These factors are associated with paroxysm in non-immune individuals. In individuals from an endemic area with age-acquired anti-disease immunity clinical symptoms are mild and the parasite killing factors are not induced.

An attempt to predict anergy in tuberculosis suspect cynomolgus monkeys

Acid-fast microorganisms were identified from the tuberculous lesions of a male cynomolgus monkey (Macaca fascicularis). Twenty-two other cynomolgus monkeys housed in the same room were presumed exposed to tuberculosis (Mycobacterium spp.). In addition to standard intradermal (ID) tuberculin testing, clinicians attempted to evaluate the immune status of these monkeys in order to identify animals exhibiting false negative (anergy) ID tuberculin tests. Twenty-one of the potentially exposed monkeys were immunized with tetanus toxoid (TT). Tetanus antitoxin (TAT) titers were measured before and after immunization. The delayed cutaneous hypersensitivity (DCH) reaction to TT was evaluated using a commercially available human test panel. Some animals did not exhibit a DCH reaction to TT. At necropsy 1 of the 21 animals exhibited tuberculous lesions, and acid-fast microorganisms were identified on direct smears of lymphatic tissue of a second animal. Although reported to be of value in assessing the cellular immune status of rhesus monkeys (Macaca mulatta), the delayed cutaneous hypersensitivity response to tetanus toxoid was not helpful during this outbreak in identifying cynomolgus monkeys infected with M. tuberculosis, or in interpreting suspect ID tuberculin tests.

Risk of occupational exposure to Herpesvirus simiae (B virus) in Quebec

Herpesvirus simiae (B virus) causes a mild infection in macaques. Transmission to humans may result in life-threatening encephalomyelitis. To evaluate the risk of occupational exposure to B virus we surveyed the directors of 11 biomedical laboratories in Quebec that use monkeys. Information was obtained on the monkey population and on the use of infection control measures recommended by the US Centers for Disease Control (CDC), Atlanta. Of the 519 monkeys belonging to susceptible species the serologic status was positive in 264 (51%), all captured in the wilds, and it was unknown in 24 (5%). All of the monkeys were caged individually, and newly acquired ones were quarantined for 2 to 8 weeks. Of the 84 workers 52 (62%) handled monkeys whose serologic status was either positive or unknown. Only five laboratories (representing 61% of the workers) complied fully with the CDC guidelines. Nine of the laboratories had a wound management protocol, but only six had a designated specialist for consultation and prophylaxis. Although no cases of B virus infection have been reported from Quebec the severity of human illness necessitates strict adherence to infection control measures and expert management of occupational exposure to susceptible monkeys.

Prevalence of natural infection with simian immunodeficiency virus and simian T-cell leukemia virus type I in a breeding colony of sooty mangabey monkeys

The seroprevalence of antibodies to simian immunodeficiency virus (SIVsmm) and simian T-cell leukemia virus type I (STLV-I) in a captive breeding colony of sooty mangabey monkeys was determined, and infection by SIVsmm was confirmed in all cases by virus isolation. Among 138 animals tested, 57 and 33% were infected with SIVsmm and STLV-I, respectively. While the proportion of female mangabeys (66%) differed significantly (P less than 0.01) from the proportion of male mangabeys (42%) infected with SIVsmm, the proportions of males and females infected with STLV-I were similar, suggesting independent transmission of the two viruses. Among mangabeys less than 1 year old, none were infected with STLV-I and only five of 27 mangabeys, all of which were at least 6 months old when first tested, were infected with SIVsmm. The data document that natural infection of sooty mangabey monkeys with SIVsmm or in association with STLV-I infection does not result in increased disease or mortality, and that transmission of both SIVsmm and STLV-I appears to occur primarily through sexual activity.

[Development of an infection in monkeys as a result of their sequential natural and experimental exposure to the hepatitis A virus]

The development of spontaneous outbreak of hepatitis A (HA) among African green monkeys kept under strict isolation conditions was studied. It was shown that in the case of introduction of HAV the infection involved all the susceptible monkeys, running a course with and without any increase in the level of activity of serum alanine aminotransferase (ALT) After inoculation of commercial gamma-globulin only the infection without the ALT activity increase developed and some monkeys had no signs of HA at all. Experimental reinfection with HAV was produced in monkeys having anti-HAV titres of less than or equal to 1:3500.

[Susceptibility of Macaca rhesus to infection with hepatitis A virus strains isolated from man and monkeys]

The results of infection of Macaca rhesus monkeys with hepatitis A virus (HAV) strains isolated from monkeys and man are presented. After inoculation of monkeys with human NAV strains the infection could not be reproduced whereas simian HAV strains were found to be pathogenic for M. rhesus monkeys both on experimental inoculation and during natural contacts with infected monkeys in the animal house.

Coenuriasis in a spectacled langur (Presbytis obscura): praziquantel treatment and the antibody response to cyst antigens

A diagnosis of coenuriasis was made in a spectacled langur raised in captivity. Multiple cysts removed from the subcutaneous tissues and later from the abdominal cavity were identified as coenuri, typical of the genus Taenia. Post-surgical treatment of the remaining cysts with praziquantel was assessed with whole body computerized tomography (CT). CT at 6 weeks post-treatment revealed a reduction in size and increased calcification of abdominal cysts as compared to pretreatment CT. Cyst fluid antigens in ELISA assays showed a high titer (1:5, 120) IgG response in the langur serum, while no IgM response could be detected. No decrease in IgG titer was seen 6 weeks after treatment. Immunoblot analyses identified several parasite-specific antigens with apparent molecular weights of greater than 92.5 (3 bands), 88, 41, 37, and 34 kDa.

Serological survey for viral diseases in the Cayo Santiago rhesus macaque population

The free-ranging population of rhesus monkeys (Macaca mulatta) on Cayo Santiago was sero-surveyed for human measles, simian virus 40, B virus (Herpes simiae), rhesus cytomegalovirus, human and simian retroviruses and encephalomyocarditis virus to determine the prevalence of these viruses in the colony. The results of this study indicate that the colony is free of SV40, HTLVIII (HIV-1), STLVIII (SIV) and SRV1; has a low prevalence of measles and EMCV; and high prevalence rates for B virus, CMV and HTLVI.

Measles in the cynomolgus monkey (Macaca fascicularis)

The measles virus is known to infect several species of monkeys. A group of 87 cynomolgus monkeys (Macaca fascicularis) was screened to observe whether there was an association between measles and the cold symptoms seen in most of the animals. Another 23 monkeys were vaccinated with attenuated measles vaccine and their antibody titres monitored to ascertain whether the vaccine would protect them against measles.

Analysis of T lymphocyte subsets in tamarins with colitis and colon cancer

The cotton-top tamarin, Saguinus oedipus, serves as an animal model for the study of human colon cancer. This New World monkey has a high incidence of colitis and colon cancer that develops spontaneously. Evidence suggests that these diseases may be the result of a virally induced immunodeficiency. We have shown that T4+/T8+ cell ratios are significantly altered in tamarins with acute colitis and colon cancers. The T4+/T8+ ratios were 1.50 +/- 0.09, 0.70 +/- 0.05, and 0.48 +/- 0.05 for negative controls, acute colitis, and cancer positive tamarins, respectively. Statistical analysis showed a significant difference (p less than or equal to .0005) between negative controls vs. acute colitis and cancer positive groups.

ELISA for detection of antibodies to a type D retrovirus, SRV-W

An ELISA was developed to detect antibodies to a Type D retrovirus, SRV-W. The interpretation of the ELISA results were based on: 1) Comparisons of known antibody positive (to a closely related type D retrovirus) and negative serum samples, 2) the ability of ELISA reactivity to be absorbed with a Type D virus but not a mock virus preparation, and 3) analysis by a Western Blot assay as an alterative way to identify antibody to the Type D retrovirus.

[The immune structure and specific laboratory indices of acute hepatitis A in lower monkeys of the Sukhumi Nursery]

The study of the rate of occurrence of hepatitis A (HA) markers among monkeys, both newly arriving and those born and living for long periods (aboriginals) in the Sukhumi farm, was carried out. The rate of detection of antibody to HAV (anti-HAV) was shown to vary from 47% (Papio hamadryas) to 100% (Macaca arctoides and Macaca fascicularis). The level of infection with HAV varied among different groups of the same species: Macaca rhesus from 30% to 96%, Papio hamadryas from 0 to 82%. During a long-term observation period seroconversion to HAV was observed in monkeys arriving to the farm from natural habitats. In M. rhesus upon arrival the anti-HAV were detected in 7% and by the end of the observation period reached 100%, in green monkeys 28% and 92%, respectively. Anti-HAV of the IgM class were detected in animals with seroconversion. In fecal extracts from M. rhesus and in the liver, feces, and intestinal contents of green monkeys HAV was found cross-reacting with simian and human sera containing anti-HAV. The virions isolated from a green monkey liver had a buoyant density in CsCl 1.36 g/cm3, and HAV from feces of a M. rhesus sedimented in the density zone of 1.34 g/cm3.