title: Facial paralysis and lymphocytic facial neuritis in a rhesus macaque (Macaca mulatta) positive for simian retrovirus type D2.
abstract: Simian retrovirus type D (SRVD) is a naturally occurring betaretrovirus in nonhuman primates of the genus Macaca. Infection can lead to a variety of clinical, hematologic, and histopathologic abnormalities. We report an unusual clinical presentation of facial paralysis and histologic  lymphocytic neuritis in an SRVD type 2 (SRVD2)-infected rhesus macaque (Macaca mulatta) with a catheter-associated vena caval thrombus, anemia, thrombocytopenia, and multisystemic lymphoid hyperplasia. At initial presentation, a right atrial mass was detected by echocardiography. The  macaque was clinically asymptomatic but had persistent anemia, thrombocytopenia, hyperglobulinemia, and later neutropenia. It was seropositive for SRV and PCR-positive for SRVD 2. Approximately 1 mo after initial presentation, the macaque developed right facial paralysis and was euthanized.  Histologic lesions included lymphoplasmacytic aggregates affecting multiple organs, consistent with SRV-related lymphoid hyperplasia. The right facial nerve showed lymphoplasmacytic inflammation. The nerve itself was negative immunohistochemically for SRV antigen, but antigen was present infrequently  in pericapillary lymphoid cells within the facial nerve and abundantly within lymphoid aggregates in the adjacent parotid salivary gland, bone marrow, and soft tissue. Known neurotropic viruses could not be identified. Given the widespread inflammation in this macaque, particularly in the  area surrounding the facial nerve, lymphocytic neuritis and facial paralysis likely were an indirect effect of SRV infection due to local extension of SRV-related inflammation in the surrounding tissue.
authors.affiliation: Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA; Laboratory Animal Resources Unit, College of Veterinary Medicine, North Carolina State, Raleigh, North Carolina, USA. Anna.L.Hampton@gmail.com
authors.forename: Anna L
authors.initials: AL
authors.lastname: Hampton
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Colby
authors.forename: Ingrid L
authors.initials: IL
authors.lastname: Bergin
mesh_terms: D000818:Animals; D000830:Animals, Laboratory; D004452:Echocardiography / Q000662:veterinary; D005155:Facial Nerve Diseases / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D005158:Facial Paralysis / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D017809:Fatal Outcome; D006942:Hypergammaglobulinemia / Q000662:veterinary; D008253:Macaca mulatta; D008297:Male; D016093:Mason-Pfizer monkey virus; D008992:Monkey Diseases / Q000473:pathology* / Q000821:virology*; D009503:Neutropenia / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012192:Retroviridae Infections / Q000150:complications / Q000473:pathology / Q000662:veterinary*; D013921:Thrombocytopenia / Q000662:veterinary