Transmission of mouse thymic virus

Mouse thymic virus (MTV) is a naturally occurring herpesvirus of mice which produces persistent infection in salivary glands. No transmission study has been reported previously. In the present work, transmissibility of MTV has been studied by close contact between cage-mates, by the transplacental route from experimentally infected pregnant mice to their foetuses at term or delivered by Caesarean section and by nursing mothers to their sucklings. Transmission of MTV was detected between cage-mates after a long period of contact. The virus was also recovered from newborns nursed by infected mothers inoculated 1 day post-delivery. However, no transmission was detected in the foetuses following infection of mothers at different stages of pregnancy.

Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum

Colonies of Cowdria ruminantium were studied in midgut epithelial cells and salivary gland acini of nymphal Amblyomma hebraeum that were infected experimentally as larvae. Colonies were found in both tissues and studied with light and electron microscopy. Colonies observed within gut cells frequently contained 2 types of the organism: electron-dense and reticulated forms. The morphology of colonies from salivary glands, as seen with light microscopy, varied from compact, densely-staining, small colonies to larger ones in which individual organisms were apparent. With electron microscopy, most organisms in salivary glands were reticulated and appeared to be dividing by binary fission. In both types of host cells, colonies often contained a dense inclusion to which reticulated organisms were adhered.

Effect of temperature on the vector efficiency of Aedes aegypti for dengue 2 virus

The effect of temperature on the ability of Aedes aegypti to transmit dengue (DEN) 2 virus to rhesus monkeys was assessed as a possible explanation for the seasonal variation in the incidence of dengue hemorrhagic fever in Bangkok, Thailand. In two laboratory experiments, a Bangkok strain of Ae. aegypti was allowed to feed upon viremic monkeys infected with DEN-2 virus. Blood-engorged mosquitoes were separated into two groups and retained at constant temperatures. Virus infection and transmission rates were determined for Ae. aegypti at intervals ranging from 4 to 7 days during a 25-day incubation period. Results of the first experiment for mosquitoes infected with a low dose of DEN-2 virus and maintained at 20, 24, 26, and 30 degrees C, indicated that the infection rate ranged from 25% to 75% depending on the incubation period. However, DEN-2 virus was transmitted to monkeys only by Ae. aegypti retained at 30 degrees C for 25 days. In the second experiment, the infection rate for Ae. aegypti that ingested a higher viral dose, and incubated at 26, 30, 32, and 35 degrees C ranged from 67% to 95%. DEN-2 virus was transmitted to monkeys only by mosquitoes maintained at greater than or equal to 30 degrees C. The extrinsic incubation period was 12 days for mosquitoes at 30 degrees C, and was reduced to 7 days for mosquitoes incubated at 32 degrees C and 35 degrees C. These results imply that temperature-induced variations in the vector efficiency of Ae. aegypti may be a significant determinant in the annual cyclic pattern of dengue hemorrhagic fever epidemics in Bangkok.

Detection of Epstein-Barr virus-associated antigens and DNA in salivary gland biopsies from patients with Sjogren's syndrome

Sjogren's syndrome (SS) is an autoimmune disorder characterized by lymphocytic infiltration of salivary and lacrimal glands. To determine whether Epstein-Barr virus (EBV) might play a role in the pathogenesis of this disorder, we used monoclonal antibodies and DNA probes to detect evidence of viral gene products and genomes in these patients' tissue biopsies and saliva. Cytoplasmic staining of epithelial cells (i.e., ductal and/or acinar cells) with monoclonal antibody against the EBV-encoded early antigen (EA-D) was noted in 8/14 salivary gland biopsies from SS patients. This antibody did not react with normal salivary glands or salivary gland tumors, nor with other tissues from SS patients. The reactive antigen in SS biopsies had a m.w. of 52,000 on the basis of immunoblotting experiments, similar to the EA-D antigen found in lymphoblastoid cells lytically infected with EBV. EBV DNA was detected in parotid biopsies from two SS patients in amounts ranging from 0.1 to 3 pg per 20 micrograms of cellular DNA. Southern blotting was used to demonstrate the reactivity with Bam V, Eco D, and Bam M probes. Parotid saliva samples from 8/20 SS patients contained EBV DNA detectable by slot blot hybridization. EBV DNA was not detected in saliva of age-matched controls, rheumatoid arthritis patients lacking sicca symptoms, or patients with benign parotid tumors. The presence of EBV in salivary gland and saliva samples was associated with clinically more severe SS, as manifested by extraglandular symptoms such as vasculitis, occurrence of "pseudolymphoma", and marked abnormalities in immunoglobulin levels. These results demonstrate an elevated content of EBV in salivary glands of SS patients, and suggest that this virus may play a role in pathogenesis.

Distribution of mouse cytomegalovirus in organs of white mice experimentally infected by natural route

One, 10, 21-day-old and adult mice were inoculated by peroral and/or intranasal routes with mouse cytomegalovirus (MCMV). In animals surviving generalized infection, the virus could be demonstrated in salivary glands up to 123 days postinfection (p.i.). In mouse females which had eaten their infected and diseased offspring, the virus was detectable in salivary glands up to day 121, p.i. On day 16 p.i., the virus was present in salivary glands, lungs and kidneys of mice of different age groups, but no virus was recovered from their Gasserian ganglia. These results were compared with those obtained after infection with murine alpha herpesvirus.

Multiplication of chikungunya virus in salivary glands of Aedes albopictus (Oahu strain) mosquitoes: an electron microscopic study

Aedes albopictus as well as Aedes aegypti is an important vector of chikungunya and dengue viruses. Electron microscopic observations on the salivary glands of Ae. albopictus infected with chikungunya virus were performed in comparing with those of Ae. aegypti infected with dengue virus. No virus budding from the cell surface of the chikungunya-infected mosquito's salivary glands was found as shown in dengue-infected ones, in contrast to the findings of the mammalian cells such as Vero, KB, IMR, J-111 and BHK-21 cells infected with chikungunya and/or dengue virus(es).

Successful treatment of murine cytomegalovirus disease does not prevent latent virus infection

9-(1,3-Dihydroxy-2-propoxymethyl)guanine (DHPG), a nucleoside analogue, inhibits the replication of human and murine cytomegalovirus (MCMV) in cell culture. We studied the effects of treatment with DHPG on acute MCMV infection in mice and assessed the impact of drug therapy on the eventual development of latent viral infection. In virus-susceptible Balb/c mice, DHPG treatment limited dissemination of virus infection and prevented death. In sublethal infection of both Balb/c and virus-resistant C3H/St mice, DHPG prevented recovery of infectious virus from visceral organs, including the spleen. Despite these effects of drug treatment on virus replication during acute infection, latent MCMV could be reactivated in vivo by immunosuppression and in vitro by spleen explantation in virtually all mice. These results indicate that successful treatment of MCMV infection and marked suppression of viral replication do not prevent establishment of viral latency.

Salivary gland disease in children: a review. Part 1: Acquired non-neoplastic disease

The early recognition of salivary gland disease depends upon a high index of suspicion by the clinician. A systematic approach to salivary gland disease in children is presented by a group of algorithms, which is supplemented by a discussion of the historical, physical, and diagnostic test findings characteristic of salivary gland pathology. Therapeutic alternatives are discussed for both neoplastic and non-neoplastic disorders.

Passive transfer of cytomegalovirus by cardiac and renal organ transplants in a rat model

Passive transfer of latent rat cytomegalovirus (R-CMV) infection by means of vascularized organ transplants was examined in inbred rat strains. LEWIS (LEW) rats 4-5 weeks old were infected with RCMV and used as donors at 5 months of age when the infection had become latent. Well-perfused LEW hearts and kidneys were transplanted into unmodified or 500-rad x-irradiated syngeneic or allogeneic Brown Norway (BN) recipients; recipients were sacrificed 3 weeks after transplantation, and RCMV virus from various organs was quantitated by means of a plaque assay. Passive transfer of latent infection could be accomplished with renal allografts (60%) and renal isografts (40%). When BN hosts were x-irradiated LEW renal allografts invariably transferred the latent infection (100%); cardiac allografts rarely did so (8%). X-irradiation of syngeneic hosts did not enhance the capacity of LEW kidneys to transfer the latent infection. The latent infection could not be transferred with thoracic duct lymphocytes. Results show the passive transfer of latent infection with well-perfused vascularized organ allografts to be a relative organ-specific phenomenon.

Sialodacryoadenitis virus-associated lesions in the lower respiratory tract of rats

Eight- to 10-week-old outbred Wistar rats were inoculated intranasally with 10(2.9) medium mouse lethal infective doses of sialodacryoadenitis (SDA) virus. Sham inoculated control rats and challenged rats were killed at 1 day intervals for the first 8 days, then on days 10, 12, 14, and 20. Typical lesions associated with SDA were seen microscopically in the salivary and lacrimal glands of inoculated rats. In addition, laryngitis, tracheitis, bronchitis, bronchiolitis, and multifocal alveolitis were present during the acute stages of the disease. Viral antigen was demonstrated in epithelial cells lining airways by immunofluorescence microscopy. SDA virus was recovered from the lower respiratory tract from days 2 to 6 post-inoculation (PI). Serum antibodies to SDA virus, but not to Sendai virus or Mycoplasma pulmonis were present in rats tested at day 20 PI. These findings demonstrate that during the acute stages of the disease, significant lesions do occur in the lower respiratory tract of SDA virus-infected rats.

Electron microscopic analysis of infection patterns for Venezuelan equine encephalomyelitis virus in the vector mosquito, Culex (Melanoconion) taeniopus

The infectious process for Venezuelan equine encephalomyelitis virus in an enzootic vector mosquito, Culex (Melanoconion) taeniopus, was examined by transmission electron microscopy. Following large dose oral infection, virus was seen in the abdominal fat body and epidermis within 1 hr of engorgement. Replicated virus appeared to leave the mesenteron 3-4 hr post-infection. Dissemination to other organs occurred between days 1 and 2 of extrinsic incubation, when the hindgut and abdominal nerve ganglia were found to be infected. Virus reached the thoracic nerve ganglia, brain and salivary glands by 4 days post-infection, and flight muscles contained virus by day 6. Virus was never detected in the malphigian tubules or ovaries of infected mosquitoes within 21 days of extrinsic incubation. These results suggest that virus particles penetrate the mesenteron and accumulate in the abdominal fat body prior to replication within the vector. This pattern differs from that reported for other arbovirus-vector pairs.

The protective effects of hyperimmune anti-murine cytomegalovirus antiserum against lethal viral challenge: the case for passive-active immunization

The administration of 0.2 ml of hyperimmune anti-mouse cytomegalovirus (CMV) antiserum intraperitoneally (ip) or intravenously provided complete protection against lethal challenge (10(5.8) PFU ip) with murine CMV. Antiserum protection was complete when the antiserum was administered as long as 24 hr after viral challenge. The administration of antiserum had little effect on the titers of virus in the organs of these animals. Ammonium sulfate-treated antiserum provided similar complete protection. Animals rechallenged with 10(6)-10(6.5) PFU of murine CMV 1 month after initial challenge, at a time when the administrated antiserum was no longer detectable, all survived. We conclude that hyperimmune antiserum can provide significant protection against otherwise lethal murine CMV infection, that the protecting material lies within the immunoglobulin fraction, and that long-term immunity results from the combined exposure to virus and antiserum. Such passive-active protection could be useful in protecting against human CMV infection.

Murine cytomegalovirus adrenalitis in athymic nude mice

During studies of the pathogenesis of murine cytomegalovirus (MCMV) infection in athymic nude mice, we noted striking virus involvement of the adrenal glands. Because patients with the acquired immunodeficiency syndrome (AIDS) have recently been reported to have adrenal necrosis and evidence of infection of the adrenal gland with human cytomegalovirus (HCMV), we have further evaluated adrenal gland involvement during MCMV infection. Following virus inoculation, MCMV replicated to high titer in the adrenal glands of T-cell deficient, homozygous nude mice, but not heterozygous littermates with intact T-cell function. Concomitant with the high titers of virus, there appeared overt histological evidence of herpes-virus virus infection accompanied by patchy necrosis of adrenal cortical and medullary tissues. Acyclovir, which inhibits growth of MCMV, reduced virus replication in the adrenal gland. Similarly, virus replication was diminished in homozygous nude mice immunologically reconstituted by infusion of normal spleen cells three weeks prior to infection. Thus, in the absence of functioning T lymphocytes, MCMV can infect and replicate in adrenal tissues causing a progressive destructive adrenalitis.

Properties of a novel DNA virus from the tsetse fly, Glossina pallidipes

Virus particles were isolated from hypertrophied salivary glands of the tsetse fly, Glossina pallidipes collected near Mombasa, Kenya. Purified virus particles were rod-shaped, 57 nm wide by 700 to 1300 nm long. Particle lengths fell into two size classes, with 'short' particles averaging 869 nm and 'long' particles 1175 nm. The virus particles morphologically resembled elongated baculovirus nucleocapsids although, unlike baculoviruses, no fully enveloped virions were found in purified preparations. The particles contained double-stranded DNA which appeared to be linear when analysed by electrophoresis in agarose gels, ethidium bromide-caesium chloride gradient centrifugation or electron microscopy (EM). There was some evidence for the DNA being heterogeneous in size from EM studies and from the observation that restriction enzyme analysis failed to provide a clear profile of DNA fragments. Protein from purified virions contained at least 12 polypeptides with a major component of 39 000 mol. wt. These results suggest that the virus cannot be placed in any of the existing taxonomic groupings of DNA viruses.

Enhanced replication of murine cytomegalovirus in murine leukemic lymphocytes

Replication in vitro of murine cytomegalovirus was found to be enhanced in lymphoid cells from leukemic (AKR/J) mice as compared with similar cells from nonleukemic animals. Prolonged productive murine cytomegalovirus infection in lymphoid organs in vivo was demonstrable only in leukemic AKR/J mice. Latent nonproductive murine cytomegalovirus infection established in young nonleukemic AKR/J mice was invariably reactivated and expressed in salivary glands and lymphoid organs after these animals became leukemic.

Restriction endonuclease digestion analysis of DNA from viruses isolated from different sites of two fatal cases of herpes simplex virus type-1 infection

Herpes simplex virus (HSV) type-1 was isolated from a fatal case of herpes simplex encephalitis (case 1) and from a fatal case of disseminated herpes simplex (case 2). The virus was isolated from the lip lesion, the frontal lobe and the temporal lobe of the brain in case 1 and from a mesenteric node, myocardium and salivary gland in case 2. Restriction endonuclease digestion analysis showed that each case was infected with different substrains of HSV. The changes in band pattern in isolates from case 1 occurred in the "variable" region of the genome, showing that viruses with such variations can be isolated simultaneously from different tissues. The changes in band patterns in isolates from case 2 indicated the presence of two virus substrains, one in the mesenteric node and salivary gland and a second in the myocardium.

Retrovirus-like particles in salivary glands, prostate and testes of AIDS patients

AIDS associated retrovirus-like particles were identified in the salivary gland, prostate and/or testicle of two AIDS patients. These findings further suggest that saliva and semen may transmit the infection to susceptible individuals.

Enhancing antibodies, macrophages and virulence in mouse cytomegalovirus infection

The infectivity of tissue culture-passed mouse cytomegalovirus (MCMV) for resident mouse peritoneal macrophages in the presence of serial dilutions of antiviral antibody was studied by fluorescent antibody staining and virus yields. Although MCMV was neutralized by high concentrations of antiserum, there was a twofold enhancement of infectivity by subneutralizing antibody concentrations. On further dilution of antiserum, significant neutralization appeared again. When F(ab')2 fragments of anti-MCMV IgG were used or when macrophages were pretreated with monoclonal antibody to Fc receptor, there was no enhancement, and no neutralization at high dilutions of antiserum. This suggests that both enhancement and high dilution neutralization are mediated via the Fc portion of IgG and Fc receptors of macrophages. Tissue culture-passed virus whose infectivity for macrophages was reduced by high dilutions of antibody was converted to a more infectious state by addition of anti-mouse immunoglobulin. Similar results were obtained with salivary gland virus, which is less infectious for macrophages and is coated with non-neutralizing antibody. Tissue culture-passed virus is known to be less virulent for suckling mice and more infectious for macrophages than salivary gland-passed virus. When tissue culture-passed virus was coated with appropriately diluted antiviral antibody, not only was its infectivity for macrophages reduced, but it also became more virulent than control virus treated with normal mouse serum. These results are interpreted in terms of the optimal density of Fc on the virus-immunoglobulin complex in relation to the density of Fc receptors on macrophages.

Association of virulence of murine cytomegalovirus with macrophage susceptibility and with virion-bound non-neutralizing antibody

A comparison was made of the virulence in vivo and the infectivity in vitro for macrophages of (i) tissue culture-passed mouse cytomegalovirus (MCMV), (ii) salivary gland virus taken 3 weeks after infection (SGV 3w), and (iii) salivary gland virus taken 1 week after infection (SGV 1w). Salivary gland virus (3w) is known to be coated with non-neutralizing antibody, and is more virulent for newborn suckling mice and less infectious for macrophages than tissue culture-passed virus (TCV). Properties of SGV 1w were similar to those of TCV. Infectivity of SGV 3w for macrophages was significantly enhanced by treatment with trypsin (10 micrograms/ml) and at the same time virulence was lost. When SGV 1w or TCV were treated with trypsin the infectivity for macrophages was unaltered as long as the inoculum was adjusted to contain the same number of p.f.u. as assayed in MEF. Trypsin-treated SGV 3w was neutralized not by rabbit anti-mouse IgG Fc, but by anti-Fab, whereas untreated virus was neutralized by both of these anti-mouse immunoglobulins. These results are discussed in terms of the association of virulence with virion-bound antibody and Fc receptors on macrophages.

The guinea pig model for Argentine hemorrhagic fever

Guinea pigs infected by the peripheral route with the XJ pathogenic strain of Junin virus showed viscerotropism mainly in reticulo-phagocytic rich organs. By immunofluorescence, heavy infection of reticular-phagocytic cells was demonstrated, supporting the leading role of these cell types. Absence of neurotropism was demonstrated by the inability to recover infectious virus, as well as the absence of antigens, immunoglobulins, or 3rd component of complement deposits, in cells, vessels, or meninges. The correlation between infectivity and antigen expression observed in organs, and the absence of evidence of immunopathologic mechanisms, strongly suggest a direct viral effect in these experimental conditions. The results show that infection of guinea pigs by the peripheral route is an adequate model for human Argentine hemorrhagic fever with the exception of central nervous system involvement. Comparisons are made with infections produced in guinea pigs by attenuated strains, as well as with the disease in primates and humans.

Rapid infection of salivary glands in Culiseta melanura with eastern equine encephalitis virus: an electron microscopic study

Transmission electron microscopy was used to determine if eastern equine encephalitis (EEE) virus infects and replicates in the salivary glands of Culiseta melanura after 3 days of extrinsic incubation (EI). The Cs. melanura studied were from a colony strain, were orally infected, and had EI periods of 55-69 hours. Both naked nucleocapsids and enveloped virions were present in aggregates, suggestive of viral replication, within salivary gland acinar cells. Nucleocapsids were present in the cytoplasm below the plasma membrane that lined apical cavities. Enveloped virions occurred in the salivary matrix within apical cavities. Some nucleocapsids appeared to be budding through the plasma membrane around apical cavities and maturing into infectious virions. These results suggest that Cs. melanura is capable of biological transmission of EEE virus after less than or equal to 3 days of EI.

Rabies virus in the salivary glands and nasal mucosa of naturally infected skunks

Several salivary glands and the nasal mucosa of rabid skunks (Mephitis mephitis) contained rabies virus. Generally titers were high in the submandibular, moderate in the parotid and low to moderate in the zygomatic, molar and sublingual salivary glands. The nasal mucosa (glands and epithelium) contained virus at low to moderate titers that occasionally were equal to titers in brain.