Calicivirus isolation and persistence in a pygmy chimpanzee (Pan paniscus).

What may be the first calicivirus isolate from any primate species, including man, was recovered from a herpesvirus-like lip lesion on a pygmy chimpanzee and then, 6 months later, from the throat of the same animal. The infected individual and its cage mates had circulating antibodies that were type-specific for this calicivirus. The agent was antigenically different from 30 other calicivirus serotypes and is tentatively designated primate calicivirus Pan paniscus type 1 (PCV-Pan 1).

Enhancement of humoral immunity by interleukin-12.

We have found that IL-12 treatment of mice leads to long-lasting enhancement in production of most antibody isotypes in conventional B-cell responses. Initial recruitment of new B-cell clones into the response is mediated by IFN-gamma, but subsequent enhancement of Ig secretion appears to be IFN-gamma-independent. We have further found that activated B cells can directly bind IL-12. Taken together, our results suggest a two-step model for the role of IL-12 in enhancement of humoral immunity. Initially, IL-12 induces production of IFN-gamma from Th1 and NK cells. Enough cytokine can be produced from either cell type to then mediate gamma 2a heavy chain isotype switching as well as temporary suppression of IgG1 production. IL-12 further stimulates post-switched cells, including cells producing IgG1, to secrete greatly increased amounts of antibody. This step is not mediated by IFN-gamma but might be due to direct IL-12 binding to activated B lymphocytes. Depletion of B1 cells by IL-12 may further enhance antibody responsiveness since B1 cells are known to competitively inhibit Ig secretion by conventional B cells. The end result is that IL-12 causes a generalized upregulation in production of all antibodies and therefore acts as a strong adjuvant for humoral as well as cellular immunity.

Three serologic types of adenovirus infections of owl monkeys.

From a colony of 131 owl monkeys, adenovirus was isolated 68 times from 433 oropharyngeal and rectal swab sample pairs collected over a 2-year period. A total of 63 of 68 adenovirus isolates were grouped by neutralization into 1 of 3 types designated owl monkey adenovirus types (OMAV Ty) I, II, and III. The OMAV Ty I and Ty II were identified by neutralization with antiserum to squirrel monkey adenovirus type I and adenovirus SV-11, respectively. The OMAV Ty III was partially neutralized by antiserum to OMAV Ty II. The OMAV Ty I was isolated from 8 of 30 newly imported owl monkeys within 3 weeks of arrival. A total of 13 of 26 owl monkeys had a fourfold or greater rise in serum-neutralization (SN) titer with 25 of 27 developing SN titers of greater than or equal to 1:80. A total of 40 of 87 other owl monkeys in the colony had SN titers of greater than or equal to 1:5. The OMAV Ty II was isolated from 51 (12%) of 433 swab samples pairs. Virus was isolated from 26 owl monkeys with 13 having persistent infections. Viral isolations spanned a 10- to 17-month period for five of these owl monkeys. In 114 owl monkeys, 101 (86%) had SN titers to OMAV Ty II greater than or equal to 1:20. The OMAV Ty III was isolated from three owl monkeys. Of 114 owl monkeys, 93 (82%) had SN titers to OMAV Ty III of greater than or equal to 1:20. Although the distribution of SN titers were similar for OMAV Ty II and Ty III, 42 (37%) of 114 owl monkeys had eightfold or greater differences in SN titers between OMAV Ty II and Ty III.

An epizootic attributable to western equine encephalitis virus infection in emus in Texas.

An epizootic of encephalomyelitis attributable to western equine encephalitis virus was identified in emus (Dromaius novaehollandiae) from several flocks in western Texas in July 1992. Affected emus ranged from 3 months to 3 years old. Morbidity of emus in 8 flocks ranged from 15 to 50%, and 17 of 193 (8.8%) emus died. The diagnosis was confirmed by isolation and characterization of the causative virus and detection of antibody to the virus in emus that were currently ill and emus that had been ill but recovered. Clinical signs varied from mild to severe and included anorexia, lethargy with sternal recumbency, ataxia, muscle tremors, head tilt, unnatural positioning of the head on the back, acute onset of paralysis, and lateral recumbency with paddling. A few emus died without prior evidence of clinical disease. Post-mortem examination revealed 3 to 5 ml of clear pale-yellow pericardial fluid that contained a fibrin clot. Volume of the contents of the proventriculus and ventriculus were less than anticipated. Microscopic examination of numerous tissues revealed multifocal vasculitis with infiltration of plasmacytes, lymphocytes, and a few heterophilic leukocytes. The epizootic developed during a period of unseasonably heavy rainfall that resulted in higher numbers of mosquitoes than was typical for that season of year. A concurrent increase in the number of horses with encephalomyelitis attributable to western equine encephalities virus was not reported.

Epizootiologic association between feline immunodeficiency virus infection and feline leukemia virus seropositivity.

Five hundred twenty-one feline serum samples submitted to the Texas Veterinary Medical Diagnostic Laboratory between Nov 1, 1988, and Jan 31, 1989 were tested for antibody to feline immunodeficiency virus (FIV) by use of an ELISA. The prevalence of FIV infection in this population was 11.3% (95% confidence interval: 8.6 to 14.0%). Serologic test results for FeLV were available for 156 of the 521 cats. A significant (P = 0.008) association between FIV infection and FeLV seropositivity was observed; FeLV-positive cats were nearly 4 times more likely to be seropositive for FIV than were FeLV-negative cats. The association remained statistically significant (P = 0.021) after adjusting for age and gender, using multiple-logistic regression analysis.

Virus isolations by the NIH and WHO Collaborating Center for Reference and Research in Simian Viruses.

Many epidemiologic studies have shown that a large percentage of monkeys regardless of their state of health have virus inhabiting their upper respiratory and intestinal tracts. The presence of these viruses could cause problems in carrying out certain experiments and in the collection of tissues for primary cell cultures. Therefore, monitoring of the viral flora of a simian colony should be a continual program. Not only could the information gained in baseline studies be of importance in selecting a particular animal or species for specific research programs, but could also be of great importance in epidemiologic studies of any viral disease outbreaks in the colony. During the calendar years 1977 and 1978, the NIH and WHO Reference Center for Simian Virology at SFRE examined a total of 5202 simian throat and rectal swabs with 630 viral isolations. There were 301 adenoviruses, 179 enteroviruses, 82 foamyviruses, 35 reoviruses, 6 herpesviruses, 7 papovaviruses, and 20 mixed isolates. The specimens and isolates have been compared by species, month and day of week collected, and program (normal or clinical).

Monoclonal antibodies to Leptospira interrogans serovar pomona.

Three monoclonal antibodies produced against Leptospira interrogans serovar pomona have been studied for their diagnostic usefulness. All three monoclonals reacted strongly in the enzyme-linked immunosorbent assay and indirect fluorescent antibody test with serovar pomona and did not react with serovars grippotyphosa, canicola, icterohaemorrhagiae and hardjo.

Natural genital herpesvirus hominis infection in chimpanzees (Pan troglodytes and Pan paniscus).

Type 2 Herpesvirus hominis was isolated from pustulovesicular lesions on the external genitalia of two chimpanzees. Histopathologic examination of biopsy specimens from both animals revealed typical herpetic changes which included necrosis, superficial ulceration acute inflammatory cell infiltration, multinucleated syncytial giant cells, and intranuclear inclusions. Large numbers of herpes-type viruses were demonstrated by electron microscopy in biopsy specimens from both animals. Serologic studies also demonstrated infection of these animals with Herpesvirus hominis.

Chemically defined serum-free media for the cultivation of primary cells and their susceptibility to viruses.

Chemically defined media SFRE-199-1 for the growth and SFRE-199-2 for the maintenance of primary baboon kidney (Bak) cell cultures were formulated by supplementing medium M199 with insulin, sodium pyruvate, zinc sulfate, and increasing arginine-HCl, cysteine, cystine, L-glutamine, L-glutamatic acid, glycine, histidine, tyrosine, and glucose to maximally active nontoxic concentrations. For prolonged maintenance of the cells, physiological pH control, and blocking of excessive lactic acid accumulation in the spent medium of the cell cultures, it is necessary to supplement the medium containing Earle's balanced salts with D-(+)galactose. The cells grew and were maintained equally well on glass or polystyrene surfaces. Selenium, when added to growth medium or substituted for insulin and zinc sulfate, did not stimulate cell growth. Electron microscopy showed that numerous dense particles, approximately 250 to 400 A in diameter, with the appearance of glycogen, were found throughout the cytoplasm in the cells grown in SFRE-199-1 and maintained in SFRE-199-2. Echovirus types 1 to 3, poliovirus types 1 to 3, coxsackievirus types B2, B4, B5, Herpes-virus hominis type 1, simian herpesvirus H. simiae and SA8, and simian adenovirus SV34 when titrated in primary Bak cells and grown and maintained in SFRE-199-1 and 2, respectively, developed titers comparable to those obtained in conventionally grown and maintained cells.

Inhibition of murine B1 lymphocytes by interleukin-12.

B1 cells are a subset of B lymphocytes found in many species and are implicated in the development of autoimmunity. B1 cells have previously been shown to be suppressed by the T helper (Th)1 cytokine interferon (IFN)-gamma, and to be stimulated by the Th2 cytokines interleukin (IL)-2, IL-4, IL-5 and IL-10. To examine further the interactions of B1 cells and Th1 cells, we have now tested the effects of the Th1 cell-inducing cytokine IL-12 on murine B1 cells. BALB/c mice were immunized with phosphorylcholine conjugated to keyhole limpet hemocyanin (PC-KLH) and simultaneously treated with 1 microgram recombinant murine IL-12 for 3 consecutive days. In addition to altering the isotype and idiotype distribution of anti-PC antibodies, IL-12 treatment was found to cause a loss of peritoneal, but not splenic B lymphocytes in immunized mice. B cell depletion required exposure to IL-12 plus antigenic stimulation. Levels of peritoneal B lymphocytes were fully restored by day 45, but the majority of these cells belonged to the B2 subset. Additionally, proliferation of B1 cells in vitro induced by IL-5 was substantially inhibited by IL-12. IL-12 itself had no effect on viable cell recovery of peritoneal cells (PeC) cultured in vitro, but viable cell recovery was significantly decreased in PeC cultured with IL-5 plus IL-12. These results show that IL-12 causes the loss of murine peritoneal B1 cells and suggest that treatment with this cytokine may be useful for disease conditions that involve B1 cell dysfunction.

Infection of baboons ("Papio cynocephalus") with rotavirus (SA11).

A recent survey of nonhuman primate sera indicated that antibody to a rotavirus (SA11) was prevalent among a wide spectrum of animals. Both New and Old World species were found with antibody, many with surprisingly high titers (1:320). Whether or not infection per se was due to SA11 or an antigenically closely related agent could not be determined by that study; however, it is apparent from this study as well as from a survey of the literature that natural as well as experimental infection of nonhuman primates occurs. Recognizing that there is a need for an animal model for the study of viruses associated with human diarrhea, a preliminary investigation attempting to ascertain the susceptibility of the baboon (Papio cynocephalus) to a rotavirus was undertaken. Inoculation of four newborn baboons with SA11 resulted in diarrhea within 24 to 48 hours in all animals. One animal died 10 days postinoculation following severe diarrhea and dehydration. Virus was isolated as well as seen by electron microscopy in the stools of all four animals.

Coronavirus-like particles in nonhuman primate feces.

Coronavirus-like particles were detected by electron microscopy in normal and diarrhea stool specimens from baboons, chimpanzees, macaques, and marmosets. There was a high prevalence of particles in both normal and diarrhea stools of older animals, whereas stools from nonweaned animals rarely contained these coronavirus-like particles.

Immunological relationship among adenoviruses of humans, simians, and nonprimates as determined by the neutralization test.

98 antisera prepared against 25 simian adenoviruses and 31 adenovirus types from various nonprimate mammals and birds were tested for their ability to neutralize 35 human adenovirus prototypes. Antisera to these human adenovirus types were similarly tested against 25 simian adenovirus prototypes. Although very few reactions to the human adenoviruses were found in antisera to nonprimate viruses, cross-reactions among the simian and human adenoviruses were more frequent. The majority of these reactions, however, were of low titer and of questionable significance. Two chimpanzee adenovirus strains--Pan 9 and SAV 21 (C 1)--were found with an immunological relationship to human adenoviruses: Pan 9 strain showed a two-way cross relationship to human adenovirus 4, and SAV 21 (C 1) was neutralized by antisera prepared against human adenoviruses 14 and 16.

Serodiagnosis of herpesvirus infection in primates.

The presence of herpesviruses in various animal tissues used for vaccine production is of importance, inasmuch as these viruses may go unrecognized, residing in latent form. Of greatest concern is Herpesvirus simiae (B virus) present in the majority of macaca species, one of the more extensively used laboratory nonhuman primates. The close antigenic relationship of B virus to human herpes strains (H. hominis) and SA8 (a baboon herpesvirus) makes serologic differentiation extremely difficult, but necessary. Complicating the differential diagnosis is the frequent infection of simian species with human strains. The present study clearly shows that many animal sera negative to herpes simplex will be negative to B virus in the neutralization test. However, a sufficient number of sera will be negative to simplex, but positive to B virus, indicating that the assumed one-way cross is invalid. Also, if antibody to simplex is present, and this antibody is present in most adult macaques, then differentiation requires testing with B virus. At least 50% of these positive sera may appear to be negative for B virus if only tested with H. hominis. Approximately 25% of the remaining positive sera will have higher titers to B virus than to herpes simplex and 25% will have the same titers to both viruses. Further, complement is required by many of the test sera to detect the presence of antibodies to B virus.

A comparison of neutralization tests for the detection of antibodies to Herpesvirus simiae (monkey B virus).

Neutralization tests used in one laboratory in the USA and one laboratory in England to detect antibodies to Herpesvirus simiae have been compared. Complete concordance in results was obtained with 53 (90%) of 59 monkey sera. The remaining six sera all had titers no greater than 1:3. Four were positive only in the American test, and two were positive only in the British test. The importance of using complement if maximum sensitivity is to be achieved in detecting antibodies to this virus has been confirmed.

Direct binding of IL-12 to human and murine B lymphocytes.

IL-12 has been shown to play a central role in cell-mediated inflammatory reactions through direct activation of T cells and NK cells. IL-12 also strongly influences humoral immunity but these effects have been thought to be indirect and caused by intermediary cytokines. Using flow cytometry, we now show that IL-12 directly interacts with B cells. Freshly isolated murine peritoneal B-1 and conventional B lymphocytes bound IL-12, but splenic B cells failed to react unless first stimulated with lipopolysaccharide. All murine B cell sources were found to express IL-12R beta 1 subunit transcripts as detected by PCR and RNase protection assays. IL-12 binding was also detected on phytohemagglutinin-stimulated human T cell blasts and Staphylococcus aureusl IL-2-stimulated B cell blasts but not on freshly isolated peripheral blood lymphocytes. Similarly, IL-12 directly bound to the human SKW6.4 Burkitt's B cell lymphoma line. In all cases positive staining was ablated by omitting IL-12 from the procedure, showing that it was not due to detection of endogenous IL-12. These findings indicate that B cells represent another major target for IL-12 in addition to T and NK cells, and that IL-12 can directly affect humoral immunity.