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Despite the lack of confirmed reports of an exogenous Simian betaretrovirus (SRV) isolated from baboons (Papio sp.), reports of simian endogenous gammaretrovirus (SERV) in baboons with complete genomes suggest that such viruses may be potentially infectious. In addition, serologic tests have repeatedly demonstrated antibody reactivity to SRV in baboons from multiple colonies. These findings complicate the management and use of such animals for research. To provide further insight into this situation, we performed in vitro and in vivo studies to determine if baboons are or can be infected with SRV. In our initial experiment, we were not able to isolate SRV from 6 seropositive or sero-indeterminate baboons by coculturing their peripheral blood mononuclear cells (PBMC) with macaque PBMC or permissive cell lines. In a subsequent experiment, we found that baboon PBMC infected in vitro with high dose SRV were permissive to virus replication. To test in vivo infectibil- ity, groups of naive baboons were infused intravenously with either (i) the same SRV tissue culture virus stocks used for the in vitro studies, (ii) SRV antibody positive and PCR positive macaque blood, (iii) SRV antibody positive or indeterminate, but PCR negative baboon blood, or (iv) SRV antibody and PCR negative baboon blood. Sustained SRV infection, as defined by reproducible PCR detection and/or antibody seroconversion, was confirmed in 2 of 3 baboons receiving tissue culture virus but not in any recipients of transfused blood from seropositive macaques or baboons. In conclusion, the data indicate that even though baboon cells can be infected experimentally with high doses of tissue culture grown SRV, baboons that are repeatedly SRV antibody positive and PCR negative are unlikely to be infected with exogenous SRV and thus are unlikely to transmit a virus that would threaten the SPF status of captive baboon colonies.

Background: Major histocompatibility complex (MHC) class II molecules expressed on B cells, monocytes and dendritic cells present processed peptides to CD4+ T cells as one of the mechanisms to combat infection and inflammation. Aim: To study MHC II expression in a variety of nonhuman primate species, including New World (NWM) squirrel monkeys (Saimiri boliviensis boliviensis), owl monkeys (Aotus nancymae), common marmosets (Callithrix spp.), and Old World (OWM) rhesus (Macaca mulatta), baboons (Papio anubis). Methods: Two clones of cross‐reactive mouse anti‐human HLADR monoclonal antibodies (mAb) binding were analyzed by flow cytometry to evaluate MHC II expression on NHP immune cells, including T lymphocytes in whole blood (WB) and peripheral blood mononuclear cells (PBMC). Results: MHC class II antibody reactivity is seen with CD20+ B cells, CD14+ monocytes and CD3+ T lymphocytes. Specific reactivity with both clones was demonstrated in T lymphocytes: this reactivity was not inhibited by purified CD16 antibody but was completely inhibited when pre‐blocked with purified unconjugated MHC II antibody. Freshly prepared PBMC also showed reactivity with T lymphocytes without any stimulation. Interestingly, peripheral blood from rhesus macaques and olive baboons (OWM) showed no such T lymphocyte associated MHCII antibody reactivity. Discussion & Conclusion: Our results from antibody (MHC II) reactivity clearly show the potential existence of constitutively expressed (with no stimulation) MHC II molecules on T lymphocytes in new world monkeys. These results suggest that additional study is warranted to evaluate the functional and evolutionary significance of these finding and to better understand MHC II expression on T lymphocytes in new world monkeys. [ABSTRACT FROM AUTHOR]

Evaluation of true equilibrium constants prior to comparison of relative stabilization is essential owing to the discrepancies that exist between equilibrium and kinetic measurements of binding constants. Equilibrium and kinetic parameters are necessary for even monomeric proteins such as myoglobin, for effective comparison of relative stabilities of the mutants. Stability of the bound ligand is affected by small structural disturbances due to other sequence differences between the two proteins even though overall structures are similar.

Non-human primates (NHPs), primarily macaques, are commonly used as non-rodent species in pre-clinical safety assessment studies. The use of macaques in such studies is increasing largely due to the development of biopharmaceutical and immunomodulatory therapies that necessitates extensive safety testing. Macaques, commonly available for use in such studies, are infected by a rich flora of herpesviruses that cause persistent, latent, life-long infections. Primary infection of immune competent macaques is typically subclinical with very little associated morbidity and mortality only in very rare cases. A life-long consequence of herpesvirus infection is periodic stochastic and frequently asymptomatic recurrences from latency throughout an infected macaque’s lifetime. With immune modulation or suppression, however, immune control of herpesvirus infections can be lost, resulting in significant disease and even death of the affected animals. Since macaques undergo primary infection with herpesviruses starting around 4-6 months-of-age when maternally-derived antibody begins to wane, it is difficult and costly to derive animals that are herpesvirus-free. Further, the herpesvirus flora and prevalence of infection in laboratory macaques mirrors that of the adult human population making the herpesvirus-infected macaque a reasonable model of the general human population. This review is intended to familiarize toxicologists performing preclinical drug safety studies with the basic biology, disease pathogenesis and consequences of immune suppression in herpesvirus-infected laboratory macaques. [ABSTRACT FROM AUTHOR]

Focally extensive alopecia affecting the distal limbs is a common clinical finding in rhesus macaque (Macaca mulatta) colonies and is both a regulatory and colony-health concern. We performed diagnostic examinations including physical exams, bloodwork, skin scrapes, surface cytology, and surface bacterial-fungal cultures on 17 rhesus macaques with this presentation of alopecia. Skin biopsies from alopecic skin obtained from each macaque were compared with those of normal skin from the same animal. Immunohistochemistry and metachromatic staining for inflammatory cells were performed to compare alopecic and normal skin. In addition, we compared these biopsies with those previously obtained from macaques with generalized alopecia and dermal inflammatory infiltrates consistent with cutaneous hypersensitivity disorders and with those from animals with normal haircoats. Bacterial and fungal cultures, skin scrapes, surface cytology, and bloodwork were unremarkable. Affected skin showed only mild histologic alteration, with rare evidence of trichomalacia and follicular loss. Numbers of mast cells and CD3+ lymphocytes did not differ between alopecic and normally haired skin from the same animal. The number of mast cells in alopecic skin from animals in the current cohort was significantly lower than that in skin of animals previously diagnosed with a cutaneous hypersensitivity disorder. Numbers of both mast cells and CD3+ lymphocytes in alopecic skin from the current cohort were similar to those from biopsies of animals with normal haircoats. Together, the clinical findings and pathology are consistent with a psychogenic origin for this pattern of alopecia in rhesus macaques., (Copyright 2011 by the American Association for Laboratory Animal Science)

Macaque models have contributed to key advances in our basic knowledge of behavior, anatomy, and physiology as well as to our understanding of a wide variety of human diseases. This issue of Comparative Medicine focuses on several of the viral agents (members of Retroviridae, Herpesviridae and 2 small DNA viruses) that can infect both nonhuman primates and humans as well as confound research studies. Featured articles also address the challenges of developing colonies of macaques and other nonhuman primates that are truly specific pathogen-free for these and other adventitious infectious agents.

A novel Respirovirus was isolated from nasopharyngeal swab specimens from clinically normal laboratory guinea pigs, and was characterized and named caviid parainfluenza virus 3 (CavPIV-3). The CavPIV-3 is enveloped, is 100 to 300 nm in diameter, and has a characteristic 15-nm-diameter chevron-shaped virus ribonucleocapsid protein. Sequence analysis of the fusion glycoprotein of CavPIV-3 revealed it to be 94% identical to human and guinea pig parainfluenza 3 (PIV-3) viruses and 80% identical to bovine PIV-3. To determine whether CavPIV-3 causes clinical disease in laboratory guinea pigs and to compare the serologic response of guinea pigs to CavPIV-3 and to other paramyxoviruses, an infection study was performed, in which groups of guinea pigs were inoculated with CavPIV-3, Sendai virus, simian virus 5 (SV-5), murine pneumonia virus (PVM), or bovine PIV-3 virus. During the course of the study, guinea pigs were maintained in an infectious disease suite, housed in Micro-Isolator cages, and were only manipulated under a laminar flow hood. Clinical signs of disease were not observed in any of the paramyxovirus-inoculated guinea pigs during the eight-week course of the study, and histologic signs of disease were not evident at necropsy eight weeks after inoculation. Guinea pigs inoculated with CavPIV-3, Sendai virus, PVM, and bovine PIV-3 developed robust homologous or heterologous serologic responses. In contrast, guinea pigs inoculated with SV-5 developed modest or equivocal serologic responses, as assessed by use of an enzyme-linked immunosorbent assay. Further, use of the SV-5 enzyme-linked immunosorbent assay resulted in the highest degree of non-specific reactivity among all of the paramyxovirus assays. In summary, CavPIV-3 is a novel guinea pig Respirovirus that subclinically infects laboratory guinea pigs, resulting in a robust serologic response, but no observed clinical or histologic disease. The CavPIV-3 fusion glycoprotein gene sequence is available from GenBank as accession No. AF394241, and the CavPIV-3 virus is available from the American Type Culture Collection as accession No. DR-1547.

Hantaviruses are a newly emerging group of rodent-borne viruses that have significant zoonotic potential. Human infection by hantaviruses can result in profound morbidity and mortality, with death rates as high as 50%, and potentially long-term cardiovascular consequences. Hantaviruses are carried by peridomestic and wild rodents worldwide and have occasionally been linked to infections in laboratory rodents. Because these viruses have been associated with significant human disease, they have become the subject of intense scientific investigation. In this review the reader is introduced to the hantaviruses, including hantavirus diseases and their pathogenesis. A review of the biology, morphology, and molecular biology of the hantaviruses with a brief overview of the ecology and biology of hantavirus-rodent pairs is also included. The risks of occupational exposure to hantaviruses, diagnosis of hantavirus infections, and methods for handling potentially infected rodents and tissues are discussed as well.