Cytomegaloviral determinants of CD8+ T cell programming and RhCMV/SIV vaccine efficacy

Simian immunodeficiency virus (SIV) insert-expressing, 68-1 rhesus cytomegalovirus (RhCMV/SIV) vectors elicit major histocompatibility complex E (MHC-E)- and MHC-II-restricted, SIV-specific CD8+ T cell responses, but the basis of these unconventional responses and their contribution to demonstrated vaccine efficacy against SIV challenge in the rhesus monkeys (RMs) have not been characterized. We show that these unconventional responses resulted from a chance genetic rearrangement in 68-1 RhCMV that abrogated the function of eight distinct immunomodulatory gene products encoded in two RhCMV genomic regions (Rh157.5/Rh157.4 and Rh158-161), revealing three patterns of unconventional response inhibition. Differential repair of these genes with either RhCMV-derived or orthologous human CMV (HCMV)-derived sequences (UL128/UL130; UL146/UL147) leads to either of two distinct CD8+ T cell response types-MHC-Ia-restricted only or a mix of MHC-II- and MHC-Ia-restricted CD8+ T cells. Response magnitude and functional differentiation are similar to RhCMV 68-1, but neither alternative response type mediated protection against SIV challenge. These findings implicate MHC-E-restricted CD8+ T cell responses as mediators of anti-SIV efficacy and indicate that translation of RhCMV/SIV vector efficacy to humans will likely require deletion of all genes that inhibit these responses from the HCMV/HIV vector.

Effective Detection of Porcine Cytomegalovirus Using Non-Invasively Taken Samples from Piglets

Shortage of human organs forced the development of xenotransplantation using cells, tissues, and organs from pigs. Xenotransplantation may be associated with the transmission of porcine zoonotic microorganisms, among them the porcine cytomegalovirus (PCMV). To prevent virus transmission, pigs have to be screened using sensitive methods. In order to perform regular follow-ups and further breeding of the animals, samples for testing should be collected by low-invasive or non-invasive methods. Sera, ear biopsies, as well as oral and anal swabs were collected from ten 10-day-old Aachen minipigs (AaMP) and tested for PCMV using sensitive nested polymerase chain reaction (PCR) as well as uniplex and duplex real-time PCR. Porcine cytomegalovirus DNA was detected most frequently in oral and anal swabs. Comparison of duplex and uniplex real-time PCR systems for PCMV detection demonstrated a lower sensitivity of duplex real-time PCR when the copy numbers of the target genes were low (less 200). Therefore, to increase the efficacy of PCMV detection in piglets, early testing of oral and anal swabs by uniplex real-time PCR is recommended.

A little cooperation helps murine cytomegalovirus (MCMV) go a long way: MCMV co-infection rescues a chemokine salivary gland defect

Cytomegaloviruses (CMVs) produce chemokines (vCXCLs) that have both sequence and functional homology to host chemokines. Assessment of vCXCL-1's role in CMV infection is limited to in vitro and in silico analysis due to CMVs species specificity. In this study, we used the murine CMV (MCMV) mouse model to evaluate the function of vCXCL-1 in vivo. Recombinant MCMVs expressing chimpanzee CMV vCXCL-1 (vCXCL-1CCMV) or host chemokine, mCXCL1, underwent primary dissemination to the popliteal lymph node, spleen and lung similar to the parental MCMV. However, neither of the recombinants expressing chemokines was recovered from the salivary gland (SG) at any time post-infection although viral DNA was detected. This implies that the virus does not grow in the SG or the overexpressed chemokine induces an immune response that leads to suppressed growth. Pointing to immune suppression of virus replication, recombinant viruses were isolated from the SG following infection of immune-ablated mice [i.e. SCID (severe combined immunodeficiency), NSG (non-obese diabetic SCID gamma) or cyclophosphamide treated]. Depletion of neutrophils or NK cells does not rescue the recovery of chemokine-expressing recombinants in the SG. Surprisingly we found that co-infection of parental virus and chemokine-expressing virus leads to the recovery of the recombinants in the SG. We suggest that parental virus reduces the levels of chemokine expression leading to a decrease in inflammatory monocytes and subsequent SG growth. Therefore, aberrant expression of the chemokines induces cells of the innate and adaptive immune system that curtail the growth and dissemination of the recombinants in the SG.

Cytomegalovirus-associated Discrete Gastrointestinal Masses in Macaques Infected with the Simian Immunodeficiency Virus

Cytomegalovirus (CMV)-associated gastrointestinal masses have been reported in human acquired immune deficiency syndrome patients. This is the first report on CMV-associated gastrointestinal masses in simian immunodeficiency virus (SIV)-infected macaques. Two SIV-infected macaques presented at necropsy with multiple nodular or umbilicated masses within the gastrointestinal tract. In one animal, the masses were located throughout the gastrointestinal tract, whereas in the other, the masses were restricted to the proximal small intestine. Grossly, the masses were indistinguishable from those caused by neoplastic conditions such as lymphoma and, histologically, were composed of hyperplastic glandular tissue, dense neutrophilic infiltrates within the lamina propria, and multifocal proprial hemorrhage. Frequent cytomegalic cells with basophilic intranuclear inclusions were found in affected regions. Immunohistochemistry for CMV demonstrated frequent immunopositive cells within affected areas. Furthermore, immunohistochemistry for the proliferation marker Ki-67 demonstrated increased proliferation in hyperplastic glands and crypts. CMV should be considered a cause of discrete mass lesions in the gastrointestinal tract of SIV-infected macaques.

Recombinant Saccharomyces cerevisiae serves as novel carrier for oral DNA vaccines in Carassius auratus

Oral delivery of DNA vaccines represents a promising vaccinating method for fish. Recombinant yeast has been proved to be a safe carrier for delivering antigen proteins and DNAs to some species in vivo. However, whether recombinant yeast can be used to deliver functional DNAs for vaccination to fish is still unknown. In this study, red crucian carp (Carassius auratus) was orally administrated with recombinant Saccharomyces cerevisiae harboring CMV-EGFP expression cassette. On day 5 post the first vaccination, EGFP expression in the hindgut was detected under fluorescence microscope. To further study whether the delivered gene could induce specific immune responses, the model antigen ovalbumin (OVA) was used as immunogen, and oral administrations were conducted with recombinant S. cerevisiae harboring pCMV-OVA mammalian gene expression cassette as gene delivery or pADH1-OVA yeast gene expression cassette as protein delivery. Each administration was performed with three different doses, and the OVA-specific serum antibody was detected in all the experimental groups by western blotting and enzyme-linked immunosorbent assay (ELISA). ELISA assay also revealed that pCMV-OVA group with lower dose (pCMV-OVA-L) and pADH1-OVA group with moderate dose (pADH1-OVA-M) triggered relatively stronger antibody response than the other two doses. Moreover, the antibody level induced by pCMV-OVA-L group was significantly higher than pADH1-OVA-M group at the same serum dilutions. All the results suggested that recombinant yeast can be used as a potential carrier for oral DNA vaccines and would help to develop more practical strategies to control infectious diseases in aquaculture.

Molecular epidemiology of porcine Cytomegalovirus (PCMV) in Sichuan Province, China: 2010-2012

Porcine cytomegalovirus (PCMV) is an immunosuppressive virus that mainly inhibits the immune function of the macrophage and T-cell lymphatic systems, and has caused huge economic losses to the porcine breeding industry. Molecular epidemiological investigation of PCMV is important for prevention and treatment, and this study is the first such investigation in Sichuan Province, Southwest China. A PCMV positive infection rate of 84.4% (865/1025) confirmed that PCMV is widely distributed in Sichuan Province. A phylogenetic tree was constructed based on the PCMV glycoprotein B gene (gB) nucleotide and amino acid sequences from 24 novel Sichuan isolates and 18 other PCMV gB sequences from Genbank. PCMV does not appear to have evolved into different serotypes, and two distinct sequence groups were identified (A and B). However, whether PCMV from this region has evolved into different genotypes requires further research. Analysis of the amino acid sequences confirmed the conservation of gB, but amino acid substitutions in the major epitope region have caused antigenic drift, which may have altered the immunogenicity of PCMV.

Mesenchymoproliferative enteropathy associated with dual simian polyomavirus and rhesus cytomegalovirus infection in a simian immunodeficiency virus-infected rhesus macaque (Macaca mulatta)

Opportunistic viral infections are common in simian immunodeficiency virus-infected rhesus macaques and include simian polyomavirus 40 (SV40), which causes interstitial nephritis, pneumonia, meningoencephalitis, and progressive multifocal leukoencephalopathy and rhesus cytomegalovirus (Macacine herpesvirus-3), which is associated with many pathologic manifestations, including the formation of neutrophil-rich gastrointestinal masses. Herein we report the findings of a simian immunodeficiency virus-infected rhesus macaque that presented to necropsy with multiple nodular masses restricted to the proximal jejunum. Histologically, the masses within the lamina propria were composed of abundant, loosely organized, mesenchymal tissue forming broad interlacing whorls and sheets admixed with variable numbers of neutrophils. Cells within the mesenchymoproliferative nodules contained numerous basophilic, intranuclear inclusion bodies with only scattered cytomegalic cells. Immunohistochemistry for rhesus cytomegalovirus and SV40 demonstrated variable numbers of immunopositive cells within the affected nodules. This report is the first description of SV40-associated pathology in the small intestine of a rhesus macaque and highlights the role that opportunistic viral infections can have on gastrointestinal pathology in immunosuppressed rhesus macaques.

[Development of the PCR-test system for detection primate betaherpesvirinae]

A PCR-test system for detection of primate Betaherpesvirinae viruses was developed. Using alignment of complete genome of human, chimpanzee, and macaque rhesus cytomegalovirus conserve regions of viral genes were found. The oligonucleotide primers for consensus conserve regions of CMV UL56 gene were developed. The conditions of PCR were optimized and primer specificity for cytomegaloviruses of different primate species was confirmed.

Rhesus cytomegalovirus a nonhuman primate model for the study of human cytomegalovirus

Human cytomegalovirus (HCMV), a member of an ancient family of viruses (Herpesviridae), has acquired the capacity to maintain a lifelong persistent infection within an immunocompetent host. Since both primary and recurrent infections are generally subclinical, host antiviral immune responses are effective at limiting the pathogenic potential of HCMV. However, the fact that HCMV can persist in the presence of those protective immune responses indicates that host immunity is unable to prevent or eliminate long-term reservoirs of virus. The ability of HCMV to persist has important clinical implications, a fact reflected by the spectrum of pathogenic outcomes observed in those without a fully functional immune system. Recurrence of viral replication or transmission of HCMV from an infected individual to those most susceptible to primary infection during immune suppression, deficiency, or immaturity can lead to multiorgan disease and, sometimes, death. The clinical need for a protective HCMV vaccine has been recognized for decades, but due to a conspiracy of factors, there is no approved vaccine despite intensive investigations to develop one. Animal models of HCMV have been used as systems of discovery and translation to understand viral mechanisms of persistence and pathogenesis, and to test concepts and modalities for the generation of immune responses that protect from primary infection and sequelae. This review summarizes studies in a nonhuman primate model of HCMV involving infection of rhesus macaques (Macaca mulatta) with rhesus cytomegalovirus (RhCMV). The RhCMV model serves as an important complement to those in other animals, particularly small animals, and the lessons learned from RhCMV should have direct clinical relevance to HCMV and the design of protective vaccines.

Protein coding content of the UL)b' region of wild-type rhesus cytomegalovirus

A recent comparison of two rhesus cytomegalovirus (RhCMV) genomes revealed that the region at the right end of the U(L) genome component (U(L)b') undergoes genetic alterations similar to those observed in serially passaged human cytomegalovirus (HCMV). To determine the coding content of authentic wild-type RhCMV in this region, the U(L)b' sequence was amplified from virus obtained from naturally infected rhesus macaques without passage in vitro. A total of 24 open reading frames (ORFs) potentially encoding >99 amino acid residues were identified, 10 of which are related to HCMV ORFs and 15 to previously listed RhCMV ORFs. In addition, the analysis revealed a cluster of three novel alpha chemokine-like ORFs, bringing the number of predicted alpha chemokine genes in this region to six. Three of these six genes exhibit a high level of sequence diversity, as has been observed for the HCMV alpha chemokine gene UL146.

Development of breeding populations of rhesus macaques (Macaca mulatta) that are specific pathogen-free for rhesus cytomegalovirus

Development of breeding colonies of rhesus macaques (Macaca mulatta) that are specific pathogen-free (SPF) for rhesus cytomegalovirus (RhCMV) is relatively straightforward and requires few modifications from current SPF programs. Infants separated from the dam at or within a few days of birth and cohoused with similarly treated animals remain RhCMV seronegative indefinitely, provided they are never directly or indirectly exposed to a RhCMV-infected monkey. By systematically cohousing seronegative animals into larger social cohorts, breeding populations of animals SPF for RhCMV can be established. The additional costs involved in expanding the current definition of SPF status to include RhCMV are incremental compared with the money already being spent on existing SPF efforts. Moreover, the large increase in research opportunities available for RhCMV-free animals arguably would far exceed the development costs. Potential new areas of research and further expansion of existing research efforts involving these newly defined SPF animals would have direct implications for improvements in human health.

Immunogenicity and protective efficacy of DNA vaccines expressing rhesus cytomegalovirus glycoprotein B, phosphoprotein 65-2, and viral interleukin-10 in rhesus macaques

Rhesus cytomegalovirus (RhCMV) infection of macaques exhibits strong similarities to human CMV (HCMV) persistence and pathogenesis. The immunogenicity of DNA vaccines encoding three RhCMV proteins (a truncated version of glycoprotein B lacking the transmembrane region and endodomain [gBDeltaTM], phosphoprotein 65-2 [pp65-2], and viral interleukin-10 [vIL-10]) was evaluated in rhesus macaques. Two groups of monkeys (four per group) were genetically immunized four times with a mixture of either pp65-2 and gBDeltaTM or pp65-2, vIL-10, and gBDeltaTM. The vaccinees developed anti-gB and anti-pp65-2 antibodies in addition to pp65-2 cellular responses after the second booster immunization, with rapid responses observed with subsequent DNA injections. Weak vIL-10 immune responses were detected in two of the four immunized animals. Neutralizing antibodies were detected in seven monkeys, although titers were weak compared to those observed in naturally infected animals. The immunized monkeys and naïve controls were challenged intravenously with 10(5) PFU of RhCMV. Anamnestic binding and neutralizing antibody responses were observed 1 week postchallenge in the vaccinees. DNA vaccination-induced immune responses significantly decreased peak viral loads in the immunized animals compared to those in the controls. No difference in peak viral loads was observed between the pp65-2/gBDeltaTM DNA- and pp65-2/vIL-10/gBDeltaTM-vaccinated groups. Antibody responses to nonvaccine antigens were lower postchallenge in both vaccine groups than in the controls, suggesting long-term control of RhCMV protein expression. These data demonstrated that DNA vaccines targeting the RhCMV homologues of HCMV gB and pp65 altered the course of acute and persistent RhCMV infection in a primate host.

Primate cytomegalovirus US12 gene family: a distinct and diverse clade of seven-transmembrane proteins

Human cytomegalovirus (HCMV; Human herpesvirus 5) and the other betaherpesviruses encode a number of distinct gene families, including the US12 family, which is represented only in the cytomegaloviruses of higher primates, and is comprised of a set of 10 contiguous genes (US12 through US21), each encoding a seven-transmembrane (7TM) protein. Nonessential for replication in cell culture but well-conserved among clinical isolates, little is known of possible US12 family member functions, other than a previously identified amino acid sequence similarity between US21 and a group of 7TM proteins that include known inhibitors of apoptosis, and a very limited description of similarity between US12 family members and G-protein-coupled receptors (GPCR). As a prelude to biochemical analysis, we have conducted a detailed analysis of the relationships among US12 family members and between these proteins and other proteins, particularly GPCR and other 7TM molecules. In most cases, the closest relatives of individual genes are their colinear counterparts in the other viruses. Thus, the initial duplication and divergence events that resulted in the current version of the US12 family preceded divergence of the rhesus and hominoid lineages. Our phylogenetic analysis indicates that the US12 family represents a distinct branch of the 7TM superfamily. Although they are distantly related, at least some of the US12 family members may have GPCR-related properties, but they are also likely to embody functions and mechanisms that differ from more conventional GPCRs. Our analyses suggest that the 7TM structure of US12 family members constitutes a functionally flexible structural scaffold that can be readily adapted to diverse functional ends. This strategy may be the driving force in the emergence of the several families of duplicated and diverged betaherpesvirus genes.

Temple monkeys and health implications of commensalism, Kathmandu, Nepal

Humans in contact with macaques risk exposure to enzootic primateborne viruses.

The threat of zoonotic transmission of infectious agents at monkey temples highlights the necessity of investigating the prevalence of enzootic infectious agents in these primate populations. Biological samples were collected from 39 rhesus macaques at the Swoyambhu Temple and tested by enzyme-linked immunosorbent assay, Western blot, polymerase chain reaction, or combination of these tests for evidence of infection with rhesus cytomegalovirus (RhCMV), Cercopithecine herpesvirus 1 (CHV-1), simian virus 40 (SV40), simian retrovirus (SRV), simian T-cell lymphotropic virus (STLV), simian immunodeficiency virus (SIV), and simian foamy virus (SFV). Antibody seroprevalence was 94.9% to RhCMV (37/39), 89.7% to SV40 (35/39), 64.1% to CHV-1 (25/39), and 97.4% to SFV (38/39). Humans who come into contact with macaques at Swoyambhu risk exposure to enzootic primateborne viruses. We discuss implications for public health and primate management strategies that would reduce contact between humans and primates.

Effect of maternal treatment with cyclic HPMPC in the guinea pig model of congenital cytomegalovirus infection

BACKGROUND

Cytomegalovirus (CMV) infection of the fetus is the leading cause of congenital infection. Using the guinea pig model of congenital CMV infection, we sought to determine whether antiviral treatment of a CMV-infected dam could improve the outcome of offspring.

METHODS

Pregnant Hartley guinea pigs were inoculated with guinea pig CMV (GPCMV) during the late second/early third trimester of gestation. Guinea pigs received either 1 dose of cyclic 1-[((s)-2-hydroxy-2-oxo-1,4,2,-dioxaphosphorinan-5-yl)methyl]cytosine dihydrate (cHPMPC; 35 mg/kg) or placebo 24 h after GPCMV infection. Guinea pigs were monitored until delivery or were killed 10 days after infection, for the evaluation of the effect of cHPMPC on viral replication by polymerase chain reaction analysis in various dam and pup tissues.

RESULTS

cHPMPC treatment of infected dams improved pup survival from 28.2% (11/39) to 83.7% (36/43) (P < .001) and extended the duration of pregnancy. cHPMPC treatment did not prevent infection of the placenta or disseminated infection of the dam and pup but significantly decreased the amount of GPCMV in tissues. GPCMV DNA levels in the placenta were reduced from 3.54 to 2.12 log(10) genome copies/ mu g of DNA (P < .0001).

CONCLUSIONS

Treatment of the GPCMV-infected pregnant dam with 1 dose of cHPMPC improves the outcome of congenital infection and decreases viral replication in a guinea pig model.

Detection of baboon cytomegalovirus (BaCMV) by PCR using primers directed against the glycoprotein B gene

We have cloned and sequenced the glycoprotein B genes from five strains of BaCMV, isolated from three subspecies of cynocephalus baboons (olive, yellow and chacma). Primers were designed using conserved DNA regions of the gB gene to allow DNA amplification from all strains of BaCMV. These regions differ sufficiently from human CMV that HCMV strains are not amplified, thus allowing differentiation of BaCMV from HCMV. These diagnostic primers were used to test crude nucleic acid extracts from 27 strains of BaCMV and detected 26 of them. Overall, the sensitivity and specificity of this assay are 96.7 and 100%, respectively. BaCMV strains isolated from yellow and olive baboons were very similar and could be discriminated from strains isolated from chacma baboons using a second set of PCR primers. Phylogenetic analysis of the gB genes supported the inferred close relationship of strains isolated from olive and yellow baboons.

Activation of Porcine Cytomegalovirus, but Not Porcine Lymphotropic Herpesvirus, in Pig‐to‐Baboon Xenotransplantation

Tissue-invasive disease due to porcine cytomegalovirus (PCMV) has been demonstrated after pig-to-baboon solid-organ xenotransplantation. Porcine lymphotropic herpesvirus (PLHV)-1 is associated with B cell proliferation and posttransplant lymphoproliferative disorder after allogeneic bone marrow transplantation in swine but has not been observed in pig-to-primate xenotransplantation. Activation of PCMV and PLHV-1 was investigated in 22 pig-to-baboon xenotransplants by use of quantitative polymerase chain reaction. PCMV was found in all xenografts; increased viral replication occurred in 68% of xenografts during immunosuppression. PLHV-1 was found in 12 xenografts (55%); no increases in viral replication occurred during immunosuppression. Control immunosuppressed swine coinfected with PCMV and PLHV-1 had activation of PCMV but not PLHV-1. PCMV, but not PLHV-1, is activated in solid-organ xenotransplantation.

Antibody responses to rhesus cytomegalovirus glycoprotein B in naturally infected rhesus macaques

Rhesus cytomegalovirus (RhCMV) exhibits strong parallels with human CMV (HCMV) in terms of nucleic and amino acid identities, natural history, and mechanisms of persistence and pathogenesis in its natural host, rhesus macaques (Macaca mulatta). To determine whether this non-human primate model would be useful to assess vaccine strategies for HCMV, host immune responses to RhCMV glycoprotein B (gB) were evaluated in RhCMV-infected monkeys. Total protein extracts were prepared from cells transiently transfected with an expression plasmid for either the full-length gB or a derivative (gBDelta, 1-680 aa) lacking both the transmembrane domain and cytoplasmic tail. Western blot analysis showed identical reactivity of macaque sera with full-length gB and its derivative gBDelta, indicating that the immunodominant epitopes of gB are contained in the extracellular portion of the protein. Using gBDelta extract as a solid phase, a sensitive and specific ELISA was established to characterize gB antibody responses in monkeys acutely and chronically infected with RhCMV. During primary infection (seroconversion), gB-specific antibodies developed concurrently and in parallel with total RhCMV-specific antibodies. However, during chronic infection gB-specific antibody responses were variable. A strong correlation was observed between neutralizing and gB-specific antibody levels in RhCMV-seropositive monkeys. Taken together, the results of this study indicate that, similar to host humoral responses to HCMV gB, anti-gB antibodies are an integral part of humoral immunity to RhCMV infection and probably play an important protective role in limiting the extent of RhCMV infection. Thus, the rhesus macaque model of HCMV infection is relevant for testing gB-based immune therapies.

Isolation of cytomegalovirus and foamy virus from the drill monkey (Mandrillus leucophaeus) and prevalence of antibodies to these viruses amongst wild-born and captive-bred individuals

Drill monkeys (Mandrillus leucophaeus) are an endangered species whose indigenous viral flora is largely unknown. We report here the isolation and characterization of both a cytomegalovirus (DrCMV) and a foamy virus (SFV-drl) from drill monkeys. Phylogenetic analysis of DNA sequence data placed the DrCMV within a primate CMV clade, and showed that SFV-drl was closely related to baboon foamy viruses. ELISA analysis demonstrated that DrCMV shared common epitopes with other primate CMVs but was distinct from human and baboon CMVs. ELISA testing of sera from wild-born and captive-bred drills indicated that the prevalence of antibodies reactive with these two viruses was 93.2% for DrCMV and 20.3% for SFV-drl.

Porcine cytomegalovirus in pigs being bred for xenograft organs: progress towards control

In human medicine, human cytomegalovirus (HCMV) is readily transmitted by organ transplant causing end-organ disease and triggering graft rejection in recipients. Because of a chronic shortage of human organs, pigs transgenic for human complement control proteins are being considered as potential donors. Such xenotransplantation raises concerns about the potential zoonotic transmission of viruses including porcine cytomegalovirus (PCMV), an endemic infection of pigs. Similar to HCMV and PCMV transmission is thought to occur in utero and perinatally. We used quantitative polymerase chain reaction to examine the prevalence, organ distribution and viral load of PCMV in human decay accelerating factor (CD55) transgenic pigs. In animals reared under conventional farm conditions, virus was identified in a wide range of organs including potential xenografts (liver, kidney and heart). The spleen was PCMV DNA positive in all infected pigs. Examination of foetal spleens failed to identify evidence of transplacental infection and prospective monitoring of two litters showed that infection occurred in the postnatal period. This transmission was prevented by hysterotomy derivation and barrier rearing. Our findings demonstrate that PCMV could be eradicated from pig herds being bred for xenotransplantation and argue that the spleen from donor animals should be examined as part of quality control procedures if clinical trials proceed.

Differential detection of B virus and rhesus cytomegalovirus in rhesus macaques

Non-human primate herpesviruses establish and maintain a lifelong persistent infection in immunocompetent hosts in the absence of clinical signs of disease. A fundamental issue for understanding the natural history of non-human primate herpesviruses is whether the viruses are maintained in a truly latent state or one characterized by a low level of chronic expression. To address this issue, a real-time PCR assay was developed to quantify Cercopithecine herpesvirus type 1 (B virus) DNA in mucosal fluids of rhesus macaques. This assay was rapid, sensitive (10 genome copies) and specific for B virus obtained from multiple species of macaques. The shedding profile of B virus was compared to another endemic herpesvirus, rhesus cytomegalovirus (RhCMV), in colony-reared monkeys. Mucosal swabs or saliva samples were taken daily from two groups of seropositive monkeys undergoing either a stressful relocation (group 1) or daily chair restraint (group 2). B virus DNA was detected in mucosal fluids from four animals relocated during the breeding season (group 1) but not from 10 animals moved at other times of the year. No B virus DNA was detected in any group 2 monkey. In contrast, RhCMV DNA was detected in the majority of animals of both groups 1 and 2. Detection of B virus DNA shedding is a relatively rare event associated with the breeding season, while RhCMV DNA is persistently detected in mucosal fluids of most monkeys.

Cytomegalovirus infection in a pig in South Africa

An 8-week-old piglet with dyspnoea, bilateral mucopurulent nasal discharge and mouth breathing was euthanased and a necropsy was performed. Apart from histological evidence of diffuse rhinitis, large intranuclear inclusion bodies, pathognomonic forporcine cytomegalovirus infection, were detected within mucous glands on the nasal turbinates. This is the first such case to be diagnosed in South Africa.

Isolation and characterization of an endogenous cytomegalovirus (BaCMV) from baboons

This report describes the isolation of CMV-like viruses from olive, yellow and chacma sub-species of baboons. The viruses were identified as CMVs by their characteristic growth properties in cell culture, virion morphology under the TEM, and antigenic cross-reactivity with other primate CMVs. The glycoprotein B gene homologue from an olive baboon CMV isolate (BaCMV OCOM4-37) was identified, cloned and sequenced. We present the sequence of this gene and by phylogenetic analysis demonstrate that BaCMV is in fact a cytomegalovirus, and is more closely related to rhesus CMV than to human CMV. An ELISA was developed to measure anti-BaCMV antibodies in baboon sera. Serological testing of colony-bred and wild-born baboons indicated that BaCMV is ubiquitous in all baboon populations, with >95% of adult baboons of all sub-species being infected.

Identification of the porcine cytomegalovirus major capsid protein gene

A major capsid protein (MCP) gene homologue of porcine cytomegalovirus (PCMV) was identified. Sequence analysis indicated that the PCMV MCP gene is 4,026 nucleotides in length encoding a protein of 1,341 amino acid residues. The predicted molecular weight of the PCMV MCP is 151,456 Da, equivalent to those of other herpesvirus MCP counterparts. Phylogenetic analysis using herpesviral MCP gene sequences confirmed that PCMV is a betaherpesvirus with higher homology with human herpesvirus-6 and -7 than human and mouse cytomegaloviruses. The serum of pig experimentally infected with PCMV did not react with bacterially expressed MCP, suggesting that the PCMV MCP may not be related to the humoral immune response in the course of PCMV infection. Also, we established polymerase chain reaction (PCR) protocols using primers corresponding to MCP gene sequences for detection of PCMV infection. The PCR protocol would be effective for the diagnosis of slow-growing PCMV infection, for which traditional methods involving virus-isolation are not useful.

Detection of infectious baboon cytomegalovirus after baboon-to-human liver xenotransplantation

Xenotransplantation is considered to be a solution for the human donor shortage. However, there is a potential risk of transmitting animal infections from the transplanted organ. The known transmissibility and clinical significance of human cytomegalovirus (HCMV) infection after allotransplantation led us to evaluate whether baboon cytomegalovirus (BCMV) transmission could occur after a baboon-to-human liver xenotransplant. We examined serial blood samples from a baboon liver recipient and isolated replication-competent CMV-like agents on days 29, 36, and 42 after xenotransplantation. BCMV and HCMV DNAs were detected in the day 29 isolate, while only HCMV DNA was detected in the other isolates. This is the first report of detecting a replication-competent virus from a source animal after xenotransplantation and is a concern with regard to potential zoonotic transmission to others.

Quantitation of porcine cytomegalovirus in pig tissues by PCR

A quantitative-competitive PCR for the quantification of porcine cytomegalovirus (PCMV) was developed. The virus was detected in a variety of pig organs (including potential xenotransplant donations), with viral loads ranging from <10 to 97 genome copies/microg of DNA. This assay will have significant utility for studying the activation and replication of PCMV and in swine models for allo- and xenotransplantation.

PCR assay for detecting porcine cytomegalovirus

This is the first published report of a PCR assay for detecting porcine cytomegalovirus (PCMV), the causative agent of inclusion body rhinitis in pigs. The DNA to be tested was extracted directly from lungs and nasal scrapings of pigs with various clinical syndromes. Fifty-nine percent (74 of 126) of tested pigs with various clinical syndromes were found to be PCR positive for PCMV. It is hoped that veterinary diagnostic laboratories will benefit by using this PCR assay for routine testing and surveillance of PCMV in pigs.

Analysis of porcine cytomegalovirus DNA polymerase by consensus primer PCR

We used a consensus primer PCR method to amplify a region of herpesviral DNA-directed DNA polymerase gene using degenerate primers for initial characterization of the porcine cytomegalovirus (PCMV) genome. The sequence of the PCR product from PCMV DNA template and its alignment with other herpesvirus DNA polymerase counterparts showed that both conserved amino acid residues and conservative amino acid substitutions are in parallel. Phylogenetic analysis revealed that PCMV should be included in the clade comprising human herpesvirus 6 and 7, rather than human and mouse cytomegaloviruses, in Betaherpesvirus subfamily.

Electrophysiology and pathology evaluation of the Yucatan pig as a non-rodent animal model for regulatory and mechanistic toxicology studies

Six male and six female Yucatan pigs were utilized to investigate the feasibility of this species as a non-rodent model for routine regulatory and mechanistic toxicology studies. This study evaluated disease surveillance and computerized electrophysiology, along with possible gross and micropathology changes. Two pigs were used as sentinel animals to evaluate the microbiological status of the vendor upon arrival; the other pigs were maintained as biomonitors and to provide baseline clinical chemistry, urinalysis, pathology and electrophysiology data. The electrophysiology tests conducted included electrocardiography (ECG), electroretinography (ERG) and quantitative electroencephalography (qEEG), which achieved consistent baseline values with acceptable intrasubject variation. Tissue cholinesterase and histochemical staining were done to determine their suitability for testing cholinesterase compounds. Evaluation of the serum chemistry profile demonstrated increased CPK and LDH, which was likely associated with slight haemolysis or minor subclinical muscle stress during handling. There were no additional clinical chemistry changes or findings in haematology, urinalysis parameters or gross pathology. Micropathology found an absence of background lesions which would interfere with routine toxicology studies, except for a mild rhinitis. The aetiological agent was identified by electron microscopy as being consistent with inclusion body rhinitis of swine, previously unreported in miniature swine. This would most notably interfere with inhalation studies. The anatomical and physiological similarities of the Yucatan pig, along with its ability to accept the performance of electrophysiology tests allow this species to be considered as a suitable model for organ system testing in toxicology studies.

Development of a PCR system for porcine cytomegalovirus detection and determination of the putative partial sequence of its DNA polymerase gene

After PCR amplification with conservative cytomegalovirus primers, a 520 nucleotide putative partial sequence of the DNA polymerase gene of porcine cytomegalovirus (PCMV) was determined. Sequence comparison revealed homology to DNA polymerase genes from various beta herpes viruses and a dendrogram was constructed depicting the relationship of PCMV to other members of the Herpesviridae family. The dendrogram indicates that PCMV is indeed a beta herpes virus that is more closely related to human herpes virus types 6 and 7 than to type 5. To address the difficulties encountered during conventional PCMV detection and characterization a set of nested PCR primers were constructed which generated DNA fragments of 415 and 257 bp from the DNA polymerase gene. The nested PCR system proved specific for PCMV and provided a novel means for the detection of this poorly characterized herpes virus in pig populations, vaccines and in organs used in xenotransplantation.

Immunohistochemical studies of productive rhesus cytomegalovirus infection in rhesus monkeys (Macaca mulatta) infected with simian immunodeficiency virus

In humans infected with the human immunodeficiency virus (HIV), clinical disease due to human cytomegalovirus (HCMV) infection is one of the AIDS-defining diseases; HCMV is the most common opportunistic infection found postmortem. Histologically, the typical lesions are characterized by "owl's eye cells." In rhesus monkeys infected with simian immunodeficiency virus (SIV), comparable lesions are caused by an infection with the rhesus CMV (RhCMV). The aim of this study was to investigate the incidence of productive and latent RhCMV infection in monkeys infected with SIV macaques (SIVmac). Eleven SIVmac-infected rhesus monkeys, which were euthanatized after developing AIDS-like disease, and 11 clinically healthy and uninfected animals comprised the study. The monkeys were screened serologically for RhCMV by western-blot analysis. Immunohistochemistry was performed by an indirect immunoperoxidase technique with a polyclonal rabbit RhCMV-antiserum. Lesions characteristic of RhCMV-associated diseases were detected histologically. All animals were latently RhCMV-infected. Seven of eleven (63.6%) SIV-infected macaques were productively RhCMV infected according to immunohistochemistry. RhCMV antigen was identified in the gastrointestinal tract, the hepatobiliary system, the lungs, and the testicles. Two of these seven animals showed characteristic inflammatory lesions associated with productive infection. Consequently, the CMV prevalence in SIVmac-infected rhesus monkeys and human AIDS patients is comparable.

Histochemical and lectinhistochemical studies on nasal mucosa of pigs with or without respiratory diseases

Histochemical and lectinhistochemical examinations were carried out on nasal mucosa of pigs with or without respiratory diseases. As the results, both acid and neutral mucins coexisted in nasal mucosa of normal pigs while acid sialomucins were mainly observed in nasal mucosa of pigs infected with Bordetella bronchiseptica and/or Pasteurella multocida. Lectinhistochemistry revealed that the nasal epithelial cells of normal pigs were rich in N-acetylgalactosamine, fucose and N-acetyl-glucosamine residues which showed a tendency to disappear in porcine cytomegalovirus infection and to increase in atrophic rhinitis, respectively.

Serological relationship among porcine cytomegalovirus Japanese isolates and a UK isolate

We isolated porcine cytomegaloviruses (PCMVs) from lung samples of fattening pigs collected in the slaughter houses of 4 prefectures of Japan. Seven isolates were obtained and used for a comparison of serological characteristics by ELISA. J1, the first field isolate in Japan, and B6 which was isolated in the UK were also used in the study. The serological relationships between the isolates were analysed by the method of Archetti and Horsfall. OF1 showed serological differences with Chiba2 and Hiroshima. Differences were also observed between Chiba2 and ChibaC, ChibaC and Kagawa. B6 showed differences with OF2, Chiba3, ChibaC and Hiroshima.

Cytomegalovirus in the principal submandibular gland of the little brown bat, Myotis lucifugus

In the course of a large scale study of salivary gland ultrastructure in chiropterans, enlarged cells infected with numerous virus particles were encountered in some acinar cells in the principal submandibular glands of two of 34 little brown bats (Myotis lucifugus). The characteristic morphology of the viruses, together with the cytomegaly that they induced, led to their identification as cytomegalovirus (CMV). In a reversal of the situation in other animal species, bat virus particles within cytoplasmic vacuoles lacked capsomeres, whereas the latter were prominent in particles free in the cytosol. The generally accepted schemes for CMV production cannot explain this seemingly aberrant morphology. This report extends to four the number of mammalian orders in which CMV has been documented by means of electron microscopy as occurring in salivary glands.

Effect of passive antibody on congenital cytomegalovirus infection in guinea pigs

Cytomegalovirus (CMV) is the most common congenital viral infection, but little is known about the protective immune mechanisms. The guinea pig (gp) model of congenital CMV was used to evaluate the effects of passive antibody given to pregnant dams on pup survival. Dams received three doses of high-titer gpCMV or control antibody on days -3, -1, and +7, or +1, +3, and +7, in relation to gpCMV challenge. gpCMV was inoculated in the late second to early third trimester at three different doses. Compared with controls, gpCMV antibody begun before gpCMV challenge significantly increased pup survival from 14% to 52%, 21% to 84%, and 51% to 77%, respectively, for the three challenge doses. gpCMV antibody started after viral challenge increased pup survival after only the lowest challenge dose (51% to 81%). Antibody did not protect against CMV infection of the pups. CMV antibody appeared to improve survival in congenital CMV infection but did not affect vertical transmission.

Screening donors for xenotransplantation. The potential for xenozoonoses

Xenotransplantation is a potential solution to the current donor shortage for solid organ transplantation. The transmission of infectious agents from donor organs or bone marrow to the recipient is a well-recognized phenomenon following allotransplantation. Thus the prospect of xenotransplantation raises the issue of xenozoonoses--i.e., the transmission of animal infections to the human host. Anticipating an increasing number of baboon to human transplants, 31 adult male baboons (Papio cynocephalus) from a single colony in the United States were screened for the presence of antibody to microbial agents (principally viral) that may pose a significant risk of infection. Antibody to simian cytomegalovirus, simian agent 8 and Epstein-Barr virus, was found in 97% of animals tested. Antibody to simian retroviruses and Toxoplasma gondii was found in 30% and 32% respectively. Discordant results were found when paired samples were examined by two primate laboratories. This was particularly noted when methodologies were based on cross-reaction with human viral antigens. These results highlight the need to develop specific antibody tests against the species used for xenotransplantation.

Seroepidemiologic studies of cytomegalovirus infection in a breeding population of rhesus macaques

A protein immunoblot (western blot) assay was developed for detection of IgG and IgM antibodies to cytomegalovirus (CMV) in banked serum and was used to study the epidemiology of infection in a breeding population of rhesus macaques. All juveniles and adults were antibody-positive to CMV. Repeated samples from 1990-born infants (n = 28) over a 12-month period allowed retrospective assessment of CMV seroconversion. Most infants (23 of 25 seroconversions) were apparently exposed to CMV during their first year of life. The IgM testing permitted identification of seroconversion time points in eight infants. Risk factors that significantly affected seroconversion probabilities in the study population were not found. Cytomegalovirus-free rhesus macaques are potentially valuable for viral teratology and pathogenesis research projects; however, present epidemiologic findings suggest that establishment of CMV-free colonies will be difficult in conventional settings.

Molecular and biological characterization of new strains of murine cytomegalovirus isolated from wild mice

Studies of the prevalence of antibody to murine cytomegalovirus (MCMV) in free-living wild mice (Mus domesticus) trapped in diverse regions of Australia and on a sub-Antarctic island indicated that 90% of 468 mice had serum antibody to MCMV. Twenty-six field isolates of MCMV were plaque-purified from salivary gland extracts of representative seropositive mice. These isolates varied considerably in their ability to replicate in the salivary glands of weanling BALB/c mice with 9 of 15 failing to reach significant titres in this organ and the titres of the remaining 6 strains varying by at least 100-fold. The high frequency of restriction fragment length polymorphisms observed suggests widespread genetic heterogeneity exists among the strains. This observation was mirrored at the polypeptide level by Western blot analyses with polyclonal antisera to MCMV. The isolation in this study of four genetically distinct strains of MCMV from a single wild mouse and several strains from other individual mice demonstrates that multiple infections with MCMV may be commonplace in wild mice.

Polyadenylic:polyuridylic acid-induced protection of BALB/c mice against acute murine cytomegalovirus infection

Treatment of BALB/c mice with poly(A):poly(U) 18 h prior to infection with a lethal dose of murine cytomegalovirus (MCMV) increased survival. In parallel with increased survival, a 10- to 100-fold reduction of plaque-forming MCMV was found in the liver and spleen of mice 4 days post-infection with a sublethal dose of MCMV. Poly(A):poly(U) did not significantly increase natural killer cell activity or prolong the duration of elevated cytotoxic activity in infected animals. The possible role of interferon in the poly(A):poly(U)-induced protection of BALB/c mice is discussed.

Pathological changes in the reproductive tract of male rhesus monkeys associated with age and simian AIDS

The pathological changes associated with ageing and simian immunodeficiency virus (SIV) infection in groups of immature, adult and ageing Rhesus monkeys were studied. Eighty three per cent (5 of 6) of uninfected ageing animals had hyperplasia of the prostate, 33 per cent (2 of 6) had mild prostatitis and in 66 per cent (4 of 6) there were calcified concretions in the seminal vesicles. The testes were normal and showed active spermatogenesis. In the SIV-infected animals, two types of lesion occurred; the most common, in 81 per cent (18 of 22 monkeys), was the presence of focal lymphoid infiltrations in the epididymis, prostate or seminal vesicles. The other was hypospermatogenesis (23 per cent, 4 of 17) with degeneration of seminiferous tubules. Immunocytochemical staining demonstrated that the lymphoid masses contained approximately equal numbers of B and T lymphocytes, but the majority of diffusely scattered cells were T lymphocytes. Staining for SIV antigen identified small numbers of positive lymphocytes and macrophages in all tissues.

Characterization of the DNA of rodent herpesviruses by restriction endonuclease analysis and hybridization

Restriction endonuclease analysis, dot-blot hybridization, and dried gel hybridization were used to differentiate mouse cytomegalovirus, rat cytomegalovirus, and mouse herpesvirus strain 76. Viral DNA was obtained directly from virus-infected mouse or rat cells. Restriction endonuclease digestion was performed by standard methods with BamHI, EcoRI, HindIII, and PstI, and DNA was analyzed by electrophoresis on agarose gels. Cross-hybridization was used to determine the degree of genetic homology among the three viruses. Electrophoretic patterns revealed clear differences between mouse cytomegalovirus and rat cytomegalovirus restriction profiles. Extensive comigration of DNA was observed for rat cytomegalovirus and mouse herpesvirus strain 76. Both viruses also shared common DNA sequences. These results suggest that mouse herpesvirus strain 76 is probably a rat cytomegalovirus strain infecting mice.

Salivary gland oncocytes in African hedgehogs (Atelerix albiventris) mimicking cytomegalic inclusion disease

The salivary glands from three African hedgehogs contained multiple foci of cytomegalic cells, which occasionally had a mild to moderate infiltrate of lymphocytes at the periphery. The cytomegalic cells were 35 to 40 microns in diameter with abundant acidophilic granular to hyalin cytoplasm. The nuclei were enlarged with clumped marginalized chromatin and a large, (6 to 8 microns in diameter) central, brightly eosinophilic nucleolus that had the appearance of an inclusion body by light microscopy. Histochemically most of the cytomegalic cells contained cytoplasmic metachromatic granules with Feyrter's thionine inclusion stain. Scattered cells at the periphery of the cytomegalic foci contained periodic acid-Schiff-positive cytoplasmic granules. Ultrastructurally the cytomegalic cells contained numerous tightly-packed, often bizarre, enlarged mitochondria that completely filled the cytoplasm. The nucleus consisted of a dense central core of chromatin associated with the nucleolus and the remaining chromatin was clumped and marginalized. Nuclear and cytoplasmic virions consistent with cytomegalovirus were not present. Histochemical stains of the nucleus for heavy metals were negative. The ultrastructural and histochemical findings of the cytomegalic cells were consistent with oncocytes. Previous reports in the literature of similar cells in the salivary glands of insectivores appear to have been erroneously described as cytomegalovirus infections.

[Significance of bovine herpesvirus 4 and its detection]

In the last years different strains of the bovine cytomegalo-virus have been isolated. They have been grouped as bovine herpes virus 4 (BHV 4) and separated from other bovine herpes viruses. Their clinical importance remains uncertain. Different tests to detect infection have been developed.

Animal cytomegaloviruses

Cytomegaloviruses are agents that infect a variety of animals. Human cytomegalovirus is associated with infections that may be inapparent or may result in severe body malformation. More recently, human cytomegalovirus infections have been recognized as causing severe complications in immunosuppressed individuals. In other animals, cytomegaloviruses are often associated with infections having relatively mild sequelae. Many of these sequelae parallel symptoms associated with human cytomegalovirus infections. Recent advances in biotechnology have permitted the study of many of the animal cytomegaloviruses in vitro. Consequently, animal cytomegaloviruses can be used as model systems for studying the pathogenesis, immunobiology, and molecular biology of cytomegalovirus-host and cytomegalovirus-cell interactions.