Long-Term Dynamics of Sin Nombre Viral Rna and Antibody in Deer Mice in Montana

Abstract

Infections with hantaviruses in the natural host rodent may result in persistent, asymptomatic infections involving shedding of virus into the environment. Laboratory studies have partially characterized the acute and persistent infection by Sin Nombre virus (SNV) in its natural host, the deer mouse (Peromyscus maniculatus). However, these studies have posed questions that may best be addressed using longitudinal studies involving sequential sampling of individual wild-caught, naturally infected mice. Using enzyme immunoassay and polymerase chain reaction (PCR) analysis of monthly blood samples, we followed the infection status of deer mice in a mark-recapture study in Montana for 2 yr. Only six of 907 samples without IgG antibody to SNV contained detectable SNV RNA, suggesting that there is a very brief period of viremia before the host develops detectable antibody. The simultaneous presence of both antibody and viral RNA in blood was detected in consecutive monthly samples for as long as 3 mo. However, chronic infection was typified by alternating characteristics of PCR positivity and PCR negativity. Two possible interpretations of these results are that 1) viral RNA may be consistently present in the blood of chronically infected deer mouse, but that viral RNA is near the limits of PCR detectability or 2) SNV RNA sporadically appears in blood as a consequence of unknown physiological events. The occurrence of seasonal patterns in the proportion of samples that contains antibody and that also contained SNV RNA demonstrated a temporal association between recent infection (antibody acquisition) and presence of viral RNA in blood.

Puumala Hantavirus Excretion Kinetics in Bank Voles (Myodes glareolus)

“…Botten et al reported an initial peak in SNV RNA levels in lung samples at 21 days PI, followed by a second peak at 60 days PI (15). In another report on SNV, Kuenzi et al found a variation in PCR positivity of blood samples from wild-caught deer mice (16). These authors suggested 2 interpretations of the results: either that viral RNA is consistently present in the blood but is near the limits of PCR detectability or viral RNA reappears in blood as a consequence of unknown physiologic events.…”

“…Animals were sampled for saliva, urine, and feces on days 0, 1, 2, 3,4,8,9,11,14,16,21,28,35,42,49,56,63,70,77,84,91, and 133 PI. Serum samples were obtained on day 21 and at the termination of the experiment (day 133 PI).…”

Characterization of Imjin Virus, a Newly Isolated Hantavirus from the Ussuri White-Toothed Shrew ( Crocidura lasiura )

“…Also, studies are warranted to ascertain if the persistence of MJNV in Ussuri shrews results from heightened regulatory T-cell responses, as described previously for SEOV-infected male Norway rats (17,18). Chronic hantavirus infection in rodents is usually characterized by alternating positivity and negativity for hantavirus RNA, instead of strict concordance between the presence of detectable anti-hantavirus antibody and that of hantavirus RNA (30). Similarly, in this study, the detection of anti-MJNV IgG antibodies in the absence of detectable MJNV RNA may be attributed either to the insensitivity of the RT-PCR analysis or fluctuating viral loads in tissues.…”

Seasonal Variation in Sin Nombre Virus Infections in Deer Mice: Preliminary Results

“…Periods of increased contact rates between deer mice, such as during the onset of breeding activities in the spring, may be correlated with recent infections (Kuenzi et al, 2005). A greater proportion of recent SNV infections were recorded in spring versus fall for deer mice in Alberta, Canada (Safronetz et al, 2006).…”