Modified Dose Efficacy Trial of a Canine Distemper-Measles Vaccine for Use in Rhesus Macaques (Macaca mulatta).

Measles virus causes a highly infectious disease in NHP. Clinical signs range from asymptomatic to fatal, although measles virus is most well-known for its characteristic generalized maculopapular rash. Along with appropriate quarantine practices, restricted human access, and appropriate personal protective equipment, vaccines are used to combat the risk of infection. The canine distemper-measles vaccine (CDMV), administered at the manufacturer's standard dose (1.0 mL IM), has been shown to be effective against clinical measles disease in rhesus macaques (Macaca mulatta). The goal of the current study was to test whether doses smaller than the manufacturer's recommended dose stimulated adequate antibody production to protect against infection. We hypothesized that either 0.25 or 0.5 mL IM of CDMV would stimulate antibody production comparable to the manufacturer's recommended dose. We found that the 0.25-mL dose was less effective at inducing antibodies than either the standard (1.0 mL) or 0.5-mL dose, which both yielded similar titers. The primary implication of this study informs balancing resource allocation and providing efficacious immunity. By using half the manufacturer-recommended dose, the 50% cost reduction may provide sufficient monetary incentive to implement, maintain, or modify measles vaccination programs at NHP facilities.

Predicting receptor functionality of signaling lymphocyte activation molecule for measles virus hemagglutinin by docking simulation.

Predicting susceptibility of various species to a virus assists assessment of risk of interspecies transmission. Evaluation of receptor functionality may be useful in screening for susceptibility. In this study, docking simulation was conducted for measles virus hemagglutinin (MV-H) and immunoglobulin-like variable domain of signaling lymphocyte activation molecule (SLAM-V). It was observed that the docking scores for MV-H and SLAM-V correlated with the activity of SLAM as an MV receptor. These results suggest that the receptor functionality may be predicted from the docking scores of virion surface proteins and cellular receptor molecules.

Multicenter Safety and Immunogenicity Trial of an Attenuated Measles Vaccine for NHP.

Measles is a highly contagious viral disease in NHP. The infection can range from asymptomatic to rapidly fatal, resulting in significant morbidity and mortality in captive populations. In addition to appropriate quarantine practices, restricted access, the immunization of all personnel in contact with NHP, and the wearing of protective clothing including face masks, measles immunization further reduces the infection risk. Commercially available measles vaccines are effective for use in NHP, but interruptions in their availability have prevented the implementation of ongoing, consistent vaccination programs. This need for a readily available vaccine led us to perform a broad, multicenter safety and immunogenicity study of another candidate vaccine, MVac (Serum Institute of India), a monovalent measles vaccine derived from live Edmonston-Zagreb strain virus that had been attenuated after 22 passages on human diploid cells.

Emerging and reemerging infectious diseases of nonhuman primates in the laboratory setting.

Despite numerous advances in the diagnosis and control of infectious diseases of nonhuman primates in the laboratory setting, a number of infectious agents continue to plague colonies. Some, such as measles virus and Mycobacterium tuberculosis, cause sporadic outbreaks despite well-established biosecurity protocols, whereas others, such as retroperitoneal fibromatosis-associated herpesvirus, have only recently been discovered, often as a result of immunosuppressive experimental manipulation. Owing to the unique social housing requirements of nonhuman primates, importation of foreign-bred animals, and lack of antemortem diagnostic assays for many new diseases, elimination of these agents is often difficult or impractical. Recognition of these diseases is therefore essential because of their confounding effects on experimental data, impact on colony health, and potential for zoonotic transmission. This review summarizes the relevant pathology and pathogenesis of emerging and reemerging infectious diseases of laboratory nonhuman primates.

Epithelial-mesenchymal transition abolishes the susceptibility of polarized epithelial cell lines to measles virus.

Measles virus (MV), an enveloped negative-strand RNA virus, remains a major cause of morbidity and mortality in developing countries. MV predominantly infects immune cells by using signaling lymphocyte activation molecule (SLAM; also called CD150) as a receptor, but it also infects polarized epithelial cells, forming tight junctions in a SLAM-independent manner. Although the ability of MV to infect polarized epithelial cells is thought to be important for its transmission, the epithelial cell receptor for MV has not been identified. A transcriptional repressor, Snail, induces epithelial-mesenchymal transition (EMT), in which epithelial cells lose epithelial cell phenotypes, such as adherens and tight junctions. In this study, EMT was induced by expressing Snail in a lung adenocarcinoma cell line, II-18, which is highly susceptible to wild-type MV. Snail-expressing II-18 cells lost adherens and tight junctions. Microarray analysis confirmed the induction of EMT in II-18 cells and suggested a novel function of Snail in protein degradation and distribution. Importantly, wild-type MV no longer entered EMT-induced II-18 cells, suggesting that the epithelial cell receptor is down-regulated by the induction of EMT. Other polarized cell lines, NCI-H358 and HT-29, also lost susceptibility to wild-type MV when EMT was induced. However, the complete formation of tight junctions rather reduced MV entry into HT-29 cells. Taken together, these data suggest that the unidentified epithelial cell receptor for MV is involved in the formation of epithelial intercellular junctions.

Considering human-primate transmission of measles virus through the prism of risk analysis.

Measles is a respiratory virus that is endemic to humans. Human-nonhuman primate (NHP) transmission of the measles virus has been shown to cause significant morbidity and mortality in NHP populations. We investigated serological evidence of exposure to measles virus in two free-ranging populations of macaques at the Bukit Timah (BTNR) and Central Catchment Nature (CCNR) reserves in Singapore and the Swoyambhu Temple in Katmandu, Nepal. At BTNR/CCNR none of the 38 macaques (Macaca fascicularis) sampled were seropositive for antibodies to measles virus. In contrast, at Swoyambhu 100% (n = 39) of the macaques (M. mulatta) sampled were seropositive for antibodies to the measles virus. Here the contrasting seroprevalences of the two sites are analyzed using risk analysis. These case studies show how risk analysis can be used to approach the phenomenon of cross-species pathogen transmission.

Retrospective evaluation of measles antibody titers in vaccinated captive gorillas (Gorilla gorilla gorilla).

Retrospective analyses of banked serum samples and medical records from captive western lowland gorillas (Gorilla gorilla gorilla) at Lincoln Park Zoo showed that vaccination of gorillas with a human vaccine induced antibody production. No significant relationship was found between the groups that received one, two, or three vaccinations and the probability of seroconversion. These data also suggested that antibodies in western lowland gorillas persist for at least 11 yr. This information is useful in the assessment of vaccination protocols for captive gorillas and in the implementation of preventive care in wild gorilla populations.

DNA vaccination of infants in the presence of maternal antibody: a measles model in the primate.

To eradicate measles in developing nations a vaccine capable of being administered at birth may be necessary. We immunized newborn rhesus macaques with naked DNA encoding the measles virus hemagglutinin, fusion and nucleoprotein genes. Prior to vaccination we passively transferred measles immunoglobulin to mimic maternal antibody. In the presence or absence of measles immunoglobulin, 23 of 25 infant macaques had detectable cell mediated immunity and 16 had protective levels of neutralizing antibody. The co-administration of an IL-2/IgG plasmid augmented the vaccine, increasing cell mediated immunity in all infants and increasing the antibody response in infants vaccinated without immunoglobulin. We show for the first time that DNA vaccination can protect a newborn primate from the high-level viremia that correlates with severe measles, even in the presence of maternal antibody. Further, the addition of a molecular IL-2 adjuvant augments this DNA vaccine.

Comparative efficacy of a canine distemper-measles and a standard measles vaccine for immunization of rhesus macaques (Macaca mulatta).

Measles virus (MV), a highly infective paramyxovirus, has caused sporadic epizootics characterized by high morbidity and increased mortality in nonhuman primates. Measles vaccines for human use, although effective, are cost prohibitive for use in primate colonies. We compared the efficacy of one or two doses of Vanguard D-M, a canine distemper-measles (CD-M) vaccine, with a single dose of Attenuvax, a human measles vaccine. Compared with 81% of animals inoculated with Attenuvax, all animals inoculated with one or two doses of Vanguard developed detectable MV antibodies. One year after immunization, six juveniles from each vaccine group, along with three unvaccinated controls, were challenged with pathogenic MV and were monitored for clinical signs of disease, viremia, viral shedding, and immune response. All uninoculated controls developed clinical disease and viremia, and shed virus in nasopharangeal secretions. Subclinical viremia without viral shedding was identified in two Attenuvax- and two single-dose Vanguard-inoculated animals. Viremia was not detected in any two-dose Vanguard-inoculated animals. Significantly higher neutralization antibody titers were observed in animals receiving Vanguard. Results of this study indicate that Vanguard is at least as efficacious as Attenuvax for protection of rhesus macaques. The considerably lower cost of Vanguard makes vaccination against measles in large breeding colonies economically feasible.

Human contact with cattle, dogs and monkeys and genetic diversity of measles viruses.

There is a very close contact among humans, cattle, dogs and monkeys in developing countries. That could lead to genetic alteration in morbillivirus isolates of measles, rinderpest, canine distemper. Emergence of novel morbillivirus strains and failures of prophylactic viral vaccines should be monitored by characterisation of genetic profiles of isolates in different species. Incorporation of additional epitopes in existing prophylactic vaccines should minimise vaccine failures attributable to such novel strains.

Colitis in a female tamarin (Saguinus mystax).

An adult wild-caught female tamarin (Saguinus mystax) housed in a biomedical research facility was found moribund and extremely dehydrated, with severe diarrhea. She initially responded to supportive therapy but died 3 days later. Necropsy findings included hyperemia of the colonic mucosa, mesenteric lymphadenopathy, acanthocephalid parasites (Prosthenorchis elegans) embedded in the mucosa of the terminal ileum and cecum, and free filarid nematodes (Dipetalonema sp.) in the abdominal cavity. Campylobacter sp. was recovered from the colon. With the exception of changes associated with the parasites, significant histologic changes were limited to the colon. Changes consistent with acute enteric viral infection were found against a background of chronic inflammation. Enterocytes were variably hypertrophied, degenerate, and attenuated. Numerous epithelial syncytial cells were present, and some affected cells (uni- as well as multinucleated) contained intranuclear inclusions. Lymphoid follicles were mildly depleted and contained rare syncytia. Measles (Morbillivirus) infection was confirmed by using immunohistochemistry, reverse transcriptase polymerase chain reaction, and Southern blot analysis. In contrast to the cutaneous rash, respiratory involvement, and low mortality characteristic of Old World monkeys with measles, severe diarrhea with high mortality occurs in New World monkeys with this disease. In addition, our case differs from previous reports of measles in New World monkeys in that syncytial cell formation apparently was limited to the colon of our animal.

Fatal measles virus infection in Japanese macaques (Macaca fuscata).

An outbreak of natural measles virus infection occurred in a group of Japanese macaques (Macaca fuscata). Over a period of 4 months, 12 of 53 Japanese macaques died following a 2-23-day history of anorexia, diarrhea, and dermatitis. The monkeys were kept in outdoor exhibits but had been moved temporarily into indoor caging and then transferred to new outdoor exhibits. Ten monkeys died while they were in temporary caging, and two monkeys died after they were moved to new outdoor exhibits. The diagnoses were made based on the results of histopathology, immunohistochemistry (IHC), in situ hybridization (ISH), and electron microscopy. Measles virus antigens were detected in the lung, stomach, skin, salivary gland, spleen, and lymph nodes. Tangled, tubular nucleocapsids compatible with paramyxovirus were noted in the lung tissue. As a result of immunosuppression following measles virus infection, various secondary infections including disseminated cytomegalovirus infection, adenoviral and bacterial pneumonia, and Candida albicans-associated gingivitis and esophagitis were noted. The primary infective source or the mode of infection could not be determined in this outbreak, but measles virus may have been transmitted to the monkeys from human visitors while the monkeys were on exhibit.

Management of a measles outbreak among Old World nonhuman primates.

BACKGROUND AND PURPOSE: A measles outbreak in a facility housing Old World nonhuman primates developed over a 2-month period in 1996, providing an opportunity to study the epidemiology of this highly infectious disease in an animal-handling setting. METHODS: Serum and urine specimens were collected from monkeys housed in the room where the initial measles cases were identified, other monkeys with suspicious measles-like signs, and employees working in the affected areas. Serum specimens were tested for measles virus-specific IgG and IgM antibodies, and urine specimens were tested for measles virus by virus isolation or reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: A total of 94 monkeys in two separate facilities had evidence of an acute measles infection. The outbreak was caused by a wild-type virus that had been associated with recent human cases of acute measles in the United States; however, an investigation was unable to identify the original source of the outbreak. Quarantine and massive vaccination helped to control further spread of infection. CONCLUSIONS: Results emphasize the value of having a measles control plan in place that includes a preventive measles vaccination program involving human and nonhuman primates to decrease the likelihood of a facility outbreak.

Nonhuman primate models of measles.

Wild measles virus isolated in a marmoset lymphoblastoid B95a cell line induced rashes and Koplik's spots when inoculated parenterally in cynomolgus and squirrel monkeys. Marked leukopenia. associated with transient decrease in the CD4(+)-to-CD8+ T-cell ratio also was induced. Virus growth, as well as histologic lesions of necrosis and giant cell formation, was observed in the lymphoid tissues. Thus clinical signs of acute measles were successfully induced in monkeys by inoculation with cell-culture-grown measles virus. These nonhuman primate models of measles will be useful for study of the pathogenesis of acute measles virus infection in terms of generalized clinical signs of disease, leukopenia, and changes in the lymphocyte subsets.

Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean sea.

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including planar, mono- and di-ortho congeners and concentrations of DDT were determined in striped dolphins affected by a morbillivirus epizootic in the western Mediterranean in 1990. Extremely high concentrations of PCBs ranging from 94 to 670 micrograms/g (wet wt) were detected in the blubber. Similarly, DDT concentrations were high, between 22 and 230 micrograms/g (wet wt). The concentrations of three non-ortho coplanar PCBs were 43 (3,3',4,4'-T4CB), 6.8 (3,3',4,4',5-P5CB), and 7.8 (3,3',4,4',5,5'-H6CB) ng/g (wet wt), respectively, the highest residue levels reported to date. The estimated 2,3,7,8-TCDD toxic equivalents of non-, mono- and di-ortho PCB congeners in striped dolphins were several times higher than those observed for other marine mammals and humans. Mono-ortho congeners contributed greater 2,3,7,8-TCDD toxic equivalents than non-ortho members. The higher ratio of 3,3',4,4',5,5'-H6CB/3,3',4,4',5-P5CB (IUPAC 169/126) suggested a strong induction of mixed function oxidase enzymes and highlighted the possibility of using this ratio as an index for risk assessment of PCB contamination in marine mammals. Elevated concentrations of PCBs may have played a role in the immune depression in striped dolphins, ultimately leading to the development of morbillivirus disease.

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.