Murine Viruses in an Island Population of Introduced House Mice and Endemic Short-Tailed Mice in Western Australia

Abstract

House mice (Mus domesticus) were recently introduced to Thevenard Island, off the northwest coast of Western Australia. This island is also habitat for an endangered native rodent, the short-tailed mouse (Leggadina lakedownensis). Concerns have been raised that house mice may pose a threat to L. lakedownensis both through competition and as a source of infection. To assess the threat to L. lakedownensis posed by viral pathogens from M. domesticus, a serological survey was conducted from 1994 to 1996 of both species for evidence of infection with 14 common murine viruses (mouse hepatitis virus, murine cytomegalovirus, lymphocytic choriomeningitis virus, ectromelia virus, mouse adenovirus strains FL and K87, minute virus of mice, mouse parvovirus, reovirus type 3, Sendai virus, Theiler's mouse encephalomyelitis virus, polyoma virus, pneumonia virus of mice, and encephalomyocarditis virus) and Mycoplasma pulmonis. Despite previous evidence that populations of free-living M. domesticus from various locations on the Australian mainland were infected with up to eight viruses, M. domesticus on Thevenard Island were seropositive only to murine cytomegalovirus (MCMV). Antibodies to MCMV were detected in this species at all times of sampling, although seroprevalence varied. Infectious MCMV could be isolated in culture of salivary gland homogenates from seropositive mice. In contrast, L. lakedownensis on Thevenard Island showed no serological evidence of infection with MCMV, any of the other murine viruses, or M. pulmonis, and no virus could be isolated in culture from salivary gland homogenates. Although MCMV replicated to high titers in experimentally infected inbred BALB/c laboratory mice as expected, it did not replicate in the target organs of experimentally inoculated L. lakedownensis, indicating that the strict host specificity of MCMV may prevent its infection of L. lakedownensis. These results suggest that native mice on Thevenard Island are not at risk of MCMV infection from introduced house mice, and raise interesting questions about the possible selective survival of MCMV in small isolated populations of M. domesticus.

Generation of a Recombinant Cytomegalovirus for Expression of a Hantavirus Glycoprotein

“…Interestingly, preexisting immunity to wt-PCMV does not interfere with the induction of an immune response against an immunogenic transgene expressed in this viral vector. This is in accordance with studies that show the presence of multiple strains of MCMV, resulting from subsequent infections, in wild mice (19). This is in contrast to HCMV infection in humans where, in healthy individuals, prior infection with either wildtype HCMV or a vaccine strain confers at least partial protection (1,25,26).…”

“…Our laboratory is interested in developing an animal model for hantavirus infections in order to explore the possible use of CMV as a vaccine vector. Advantages to the use of CMV as a vector include the following: (i) CMV normally does not cause severe disease in an immunocompetent host; (ii) CMV exists as a latent or persistent infection for the life of the host, resulting in continuous antigenic stimulation (1); (iii) healthy animals can be infected with more than one strain of CMV, indicating that the presence of preexisting immunity against the virus does not preclude immunization with a second strain expressing the same or alternative antigens (19); (iv) in cell culture, the virus has a relatively slow replication cycle, allowing expression of a protein for several days before the death of permissive cells; and (v) CMV can abortively infect many cell types, which can result in the expression of immediate-early and some early genes without resulting in cell death. This overcomes the problems with a vector such as vaccinia virus, which is toxic to many cell types.…”

Absence of Frequent Herpesvirus Transmission in a Nonhuman Primate Predator-Prey System in the Wild

“…In these studies, the genetic similarity between host species appeared to influence the replicative capacity of the respective CMVs, with HCMV replication being reduced only 10-fold in chimpanzee cells, compared to being nondetectable in cells from mice. In vivo studies support this level of species specificity, with no cross-species transmission/persistence being observed for murine CMV (MCMV) from naturally infected Mus musculus domesticus (house mouse) to native Leggadina lakedownensis (short-tailed mice) following the release of MCMV-infected house mice into the Thevenard Island natural reserve (36). In the Thevenard Island study, MCMV did not replicate even following direct inoculation of virus into L. lakedownensis.…”

MHC class I immune evasion in MCMV infection

“…Between 60 and 90% of mice are infected in the wild-similar to the prevalence of HCMV in humans-and »34% of mice are infected with multiple isolates [2][3][4][5]. Human CMV is commonly transmitted via infectious secretions (including saliva, urine, and breastmilk), across the placenta, or by solid organ transplant.…”