Infected Marmosets Research Articles

Immunization of marmosets with Trypanosoma cruzi cell surface glycoprotein (GP90)

Marmosets ( Callithrix jacchus) have been immunized with a vaccine comprising a Trypanosoma cruzi 90K cell surface glycoprotein and the adjuvant saponin; a combination previously shown to be protective in mice. Immunization was by two s.c. injections one month apart and non-lethal challenge of homologous Y strain T. cruzi was given one month after the booster immunization. No anti- T. cruzi antibodies were detected after the first immunization but high levels developed after boosting. Immunization caused a significant decrease in the levels of acute phase blood parasitaemia, however, both immunized and control animals remained xenodiagnosis positive 60 weeks after infection. No ECG aberrations, histopathological lesions or anti-tissue antibodies were detected in infected marmosets.

Diagnosis of hepatitis A infection: Comparative specificity of IgM capture assays using antigens derived from tissue cultures and marmoset faeces

Hepatitis A virus (HAV) antigens from two tissue culture sources were compared with that from the faeces of infected marmosets to determine whether the former were satisfactory substitutes. Sera from 313 healthy blood donors and 417 patients with various clinical conditions were tested for IgM class antibody to HAV (anti-HAV IgM) using an IgM antibody capture assay (MACRIA) with each of the 3 antigens. Forty-eight specimens, all from cases of acute hepatitis, were positive in MACRIA with all 3 antigens. Only 2 of the 313 blood donors' sera reacted at all. These reactions were weak and did not arise with all antigens. Weakly reactive specimens were also found in 3 out of the 13 clinical categories. Overall 12 weak reactions arose with the faecal antigen and 8 and 7 with the two tissue culture antigens. Rheumatoid factor (RhF) was detected in 8 of the weakly reactive specimens and these had significantly higher titres of anti-HAV than sera known to contain RhF that were unreactive in MACRIA. It is concluded that tissue culture derived HAV antigen should replace that from primates on the grounds of quality, economy and convenience: also that non-specific activity in HAV MACRIA is usually due to a combination of RhF and high anti-HAV titres, but is infrequently strong enough to cause reactions interpreted as positive.

A cytotoxic T-lymphocyte line propagated from a rabbit infected with sheep associated malignant catarrhal fever

The propagation of a cell line from a rabbit affected with the sheep associated form of malignant catarrhal fever is described. Immunological and morphological characteristics of the cell indicated that it was a T-lymphocyte and the presence of electron dense cytoplasmic granules suggested that the cell could be further classified as a large granular lymphocyte. The cell line required a feeder layer and was cytotoxic to both primary cell cultures and cell lines, a characteristic of large granular lymphocytes. No evidence of the nature of the agent could be detected but as few as 10(2) cells transmitted the disease. These findings are discussed and the possibility that infection and subsequent dysfunction of large granular lymphocytes may have a central role in the pathogenesis of malignant catarrhal fever is considered. That cells with similar characteristics have been derived from Herpesvirus saimiri and H ateles infected marmoset lymphocytes suggests that the lymphoproliferation associated with infection by these two simian herpes-viruses and malignant catarrhal fever may have a similar pathogenesis.

The pathogenicity of a newly discovered human mycoplasma (strain G37) for the genital tract of marmosets.

In an attempt to demonstrate the pathogenicity of a newly discovered mycoplasma (strain G37) isolated from the human genital tract, six female marmosets (Callithix jacchus) were inoculated intravaginally. Four of the animals were infected as indicated by repeated recovery of the organisms on vaginal swabbing, and infection persisted for 72-149 days or more. In addition, the infected marmosets exhibited a serum antibody response detected most easily by an immunofluorescence technique, and a persistent vaginal polymorphonuclear leucocyte response not seen in two uninfected and in two uninoculated animals.

Infection of marmosets with parainfluenza virus types 1 and 3.

Infection of wild marmosets (Saguinus mystax) with strains of parainfluenza virus types 1 and 3 resulted in acute respiratory infection. Virus replication in the upper respiratory tract was of a degree similar to that seen in children acutely infected with parainfluenza viruses. Serum antibody developed with both virus types; however, local secretory antibody was not detectable. The infection was transmissible to susceptible animals up to 3 days inoculation of the primary animal.

Dissociation of hepatitis A virus antigen-anti-HAV antibody complexes by 2-mercaptoethanol and dithiothreitol.

Intravenous inoculation of two marmosets and one chimpanzee with hepatitis A virus (HAV) resulted in the replication of virus in liver, excretion of HAV particles in stool, and the appearance of circulating antibodies specific for hepatitis A. The development of an early antibody response in the chimpanzee and in one of the two infected marmosets was shown to interfere with the serologic detection of HAV antigen (HAV Ag) in homogenates of acute phase liver tissue obtained from these animals. Treatment of HAV Ag-positive and IgM anti-HAV-positive liver homogenates with thiol reducing compounds was shown to release HAV Ag from in vitro formed immune complexes. The increased RIA response for HAV Ag in homogenates treated with 2-mercaptoethanol (2-ME) or dithiothreitol (DTT) was further shown not to be due to activation of HAV Ag itself or to a nonspecific effect on the RIA coating antibody, radiolabeled probe, or homogenized liver tissue. IgG and IgM double-antibody sandwich RIAs for HAV Ag were also compared for their ability to detect HAV Ag under reducing and nonreducing conditions. Application of the 2-ME or DTT treatment procedure to the serologic detection of other viral antigens or viruses whose presence in blood, stool, tissue macerate, or other milieu may be masked by specific antibody appears to be feasible.

Syncytium-forming virus of common marmosets (Callithrix jacchus jacchus).

This communication describes the isolation and characterization of a new syncytium-forming virus of common marmosets (Callithrix jacchus jacchus). The virus, isolated from skin explants and peripheral leukocytes of healthy animals, induced syncytia and subsequent cytolysis of several human, simian, and rodent fibroblastic cultures and induced a carrier state in mixed fibroblastic-epithelial or epithelial cell lines. Cytoplasmic and nuclear viral antigen was demonstrated in infected cells by indirect immunofluorescence tests using serum obtained from persistently infected common marmosets. Abundant virus particles were detected within cisternae of endoplasmic reticulum of lytically infected cells by electron microscopy. The virus incorporated [3H]uridine, banded at a density of 1.14 to 1.16 g/cm3 in sucrose, and possessed ribonucleic acid-dependent deoxyribonucleic acid polymerase. No antigenic cross-reactivity was detected between the marmoset virus and simian foamy virus serotypes 1 to 8 in neutralization and immunofluorescence assays. A seroepidemiological survey of a marmoset colony revealed that 53.5% of common marmosets contained antibodies against the virus, whereas other species of marmosets maintained in the same colony remained free of antibodies.

Ureaplasmas in the marmoset (Callithrix jacchus): transmission and elimination.

All adult marmosets tested had ureaplasmas in their throats but not in the lower respiratory tract, and rarely in the genital tract. Ureaplasmas persisted in the throat of a marmoset separated from the colony for 44 days. They could not be recovered from the animals for at least nine weeks after a course of minocycline. Airborne reinfection did not occur when these animals were surrounded by, but separate from, infected marmosets. It occurred when the minocycline-treated animals were caged with the infected marmosets or were inoculated. The genital tract was more difficult to infect than the oropharynx.

Sensitivity of the Virus Isolation and Immunofluorescent Staining Methods in Diagnosis of Infections with Herpes Simplex Virus

Tissues from marmoset monkeys infected with herpes simplex virus (HSV, Herpes-virus hominis) were utilized to evaluate the relative sensitivity and limitation of the virus isolation technique and the immunofluorescent (fluorescent antibody or FA) staining method for diagnosis of HSV infection. HSV encephalitis and/or disseminated infection in marmosets were established by intracerebral, intramuscular, or intravenous inoculation of the virus. Brain tissues, liver, spleen, kidney, adrenal gland, lymph node, and lung were harvested and prepared for the virus isolation procedure in tissue culture and for direct FA staining. Data from six marmosets infected with HSV type 1 and two infected with type 2 indicated that the virus isolation method was more sensitive and reliable than the FA staining technique. False-negative results by FA staining were found in two situations: (1) presence of focal lesions that were missed by the frozen sections, and (2) presence of low concentrations of virus in tissue (is less than or equal to 3.5 log10 50% tissue culture infective doses/g). FA staining provides a rapid method for detection of viral antigens, but isolation of virus in tissue culture is required for a conclusive diagnosis of active infection.

757 SENSITIVITY OF VIRUS ISOLATION AND IMMUNOFLUORESCENT STAINING IN DIAGNOSIS OF HERPESVIRUS HOMINIS INFECTION

Herpesvirus hominis encephalitis is usually confirmed by virus isolation and immunofluorescent (F-A) staining of the brain tissues. We utilized brain and other tissues from marmoset monkeys infected with H. hominis to evaluate the sensitivity of these two methods. H. hominis encephalitis and/or disseminated infection in marmosets were established by inoculation of the virus by intracerebral, intramuscular, or intravenous route. Various organtissues were harvested and prepared for 1) infectivity titration in cultured cells of human embryonic lung fibroblasts, 2) direct F-A staining, and 3) histopathological study. The following tissues were examined: cerebrum, cerebellum, medulla, liver, spleen, kidney, adrenal, lymph node and lung. Data from six marmosets infected with H. hominis type 1 and two infected with type 2 were analyzed. Our findings indicated that virus isolation in tissue culture system was more sensitive and reliable than the F-A staining method. False negative results by F-A staining were found in two conditions: 1) presence of focal lesions which were missed by the frozen sections, and 2) presence of low concentrations of the virus in tissues (≤3.5 Log10 TCID50/gram). F-A staining method may provide a rapid diagnosis (within 1 to 2 hours), but virus isolation will give a conclusive diagnosis.

Biophysical and biochemical properties of CR326 human hepatitis A virus

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 mmu spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests by infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, identical 27 mmu viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The buoyant density of the virus in CsCl was 1.34 and it was heat (60 C), ether, and acid stable but was destroyed by heat (100 C), formalin (1:4000), and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

The effect of an immunosuppressive drug (azathioprine) on the latent infection of marmoset monkeys (Callithrix jacchus) with the oncogenicHerpesvirus saimiri

Callithrix jacchus (CJ) marmoset monkeys can be latently infected with Herpesvirus saimiri (HVS). In order to determine whether this resistance to the oncogenic potential of HVS could be due to the immune surveillance, azathioprine, a known immunosuppressive drug, was given to 7 latently infected CJ marmosets. The animals died within 147 days probably from side effect caused by azathioprine, but no animal developed a tumor.

Physical, Chemical and Morphologic Dimensions of Human Hepatitis A Virus Strain CR326

CR326 human hepatitis A virus purified by isopycnic banding from infected marmoset sera was shown to consist of 27 nm spherical particles on electron microscopic examination. The particles were identified as hepatitis A virus by tests for infectivity and by specific neutralization of infectivity with convalescent human hepatitis A serum. Also, indentical 27 nm viruses in liver extracts gave specific reactions with hepatitis A antisera when tested by immune electron microscopy. The bouyant density of the virus in CsCl was 1.34 and it was heat (60 degrees), ether and acid stable but was destroyed by heat (100 degrees), formalin (1:4000) and ultraviolet irradiation. Electron microscopic studies of sections of infected marmoset liver showed intracytoplasmic virus particles, usually in vesicles. Presumptive findings for RNA, together with the intracytoplasmic location of the virus, indicated the virus to be of RNA-type. The attributes of the virus indicate it is closely related to the enterovirus family and not to hepatitis B virus.

Attempted isolation of hepatitis viruses in marmosets.

In a study being reported concurrently, we confirmed the observation of Deinhardt et al. [1] that a pool of fifth passage sera from marmosets originally inoculated with human hepatitis material was transmissible in marmosets and produced a hepatitislike picture [2]. That study characterized the infection in marmosets following inoculation with the Barker strain of marmoset hepatitis virus and reported some physical characteristics of the agent. Histological studies demonstrated in the livers of infected animals a characteristic inflam-

Characterization of marmoset hepatitis virus.

The study of human viral hepatitis has been hampered by lack of susceptible tissue cultures or animals [1, 2]. An encouraging lead was recently obtained by Deinhardt et al. [3] who inoculated human sera into marmosets and obtained from the serum of certain inoculated animals a transmissible agent that produced histologic hepatitis associated with a rise in serum transaminase. Their initial report dealt with the isolation of the virus from human materials and with the clinical and histological features of the infection in marmosets. Hepatitis was not found in control animals in their study. A brief report [4] noted that commercial pooled human IgG strikingly reduced the infectivity of infectious marmoset sera, but this could not be confirmed in later experiments [5]. Using infectious marmoset sera kindly supplied by Deinhardt and Holmes, we have confirmed the existence of a transmissible hepatitis in marmosets and have investigated the physical properties of the virus and the characteristic features of the infection.

A New Member of the Herpesvirus Group Isolated from South American Marmosets

Summary A herpesvirus was isolated from two sick marmoset monkeys (Tamarinus nigricollis), that were believed to be infected with a helminth. The same virus was isolated directly from the kidneys and lungs of two different monkeys. It produced an effect in tissue culture cells resembling that of herpesvirus. The virus produced rapid, fatal infection in marmosets and in suckling mice; and it produced pocks on the chorioallantoic membrane. Antigenically, this virus of new world monkeys was found to be different from classical herpes simplex virus and from B virus of old world monkeys, with no detectable cross reactivity. Its size and structure also show that the virus belongs in the herpes group, which may be briefly characterized as viruses containing DNA cores and possessing icosahedral symmetry with 162 hollow capsomeres. The behavior of the marmoset agent in tissue culture places it in herpesviruses of subgroup A (high titer of free virus) as against those in subgroup B (free virus uncommon). By using primary kidney cell cultures of rabbit and of green and rhesus monkeys, it is possible to distinguish among the primate herpesviruses of subgroup A on the basis of the fact that the rabbit cultures are susceptible to all three, and green monkey cultures to both, of the monkey viruses (old world and new world), but not to the virus of man, whereas rhesus cultures are susceptible only to the old world monkey virus.