Lausannevirus Seroprevalence among Asymptomatic Young Adults

Abstract

Objectives: The giant Lausannevirus was recently identified as a parasite of amoeba that replicates rapidly in these professional phagocytes. This study aimed at assessing Lausannevirus seroprevalence among asymptomatic young men in Switzerland and hopefully identifying possible sources of contact with this giant virus. Methods: The presence of anti-Lausannevirus antibodies was assessed in sera from 517 asymptomatic volunteers who filled a detailed questionnaire. The coreactivity between Lausannevirus and amoeba-resisting bacteria was assessed. Results: Lausannevirus prevalence ranged from 1.74 to 2.51%. Sporadic condom use or multiple sexual partners, although frequent (53.97 and 60.35%, respectively), were not associated with anti-Lausannevirus antibodies. On the contrary, frequent outdoor sport practice as well as milk consumption were significantly associated with positive Lausannevirus serologies (p = 0.0066 and 0.028, respectively). Coreactivity analyses revealed an association between Criblamydia sequanensis (an amoeba-resisting bacterium present in water environments) and Lausannevirus seropositivity (p = 0.001). Conclusions: Lausannevirus seroprevalence is low in asymptomatic Swiss men. However, the association between virus seropositivity and frequent sport practice suggests that this member of the Megavirales may be transmitted by aerosols and/or exposure to specific outdoor environments. Milk intake was also associated with seropositivity. Whether the coreactivity observed for C. sequanensis and Lausannevirus reflects a common mode of acquisition or some unexpected cross-reactivity remains to be determined.

Marseillevirus in the Pharynx of a Patient with Neurologic Disorders

“…Unexpectedly, seroprevalence studies conducted in the general population showed high (up to 13%) positivity rates of Marseillevirus IgG, which suggested a common human exposure ( 3 – 5 ). Presence of Marseillevirus in a symptomatic human was reported in 2013 in an 11-month-old boy with lymphadenitis and possibly corresponded to a primary infection ( 6 ).…”

“…Metagenomics then unexpectedly identified Marseillevirus-related sequences in blood of healthy donors ( 3 ), which was confirmed by PCR, fluorescence in situ hybridization, and serologic testing. Further PCR and serologic studies suggested substantial exposure of humans to marseilleviruses ( 4 , 5 ). …”

Reply to Sauvage et al

“…Indeed, PCR-positive results must be confirmed using other primer sets (as was the case for primers ORF152 and ORF268 in the original blood donor study [2]), using other techniques (such as serology, microscopy, FISH, IF, immunohistochemistry, whole-genome sequencing, and proteomics, as in our previous studies [1–3]), and by other laboratories. Of note, independent of our work, Gilbert Greub's team in Lausanne detected Lausannevirus, another Marseillevirus, with a seroprevalence ranging from 1.74% to 2.51% in healthy Swiss men [4]. …”

A Need to Discover the World of Giant Viruses

“…Also, for the first time, these techniques have enabled the isolation of Mimivirus from a respiratory sample [18,19] and the stools of a patient with pneumonia [20]. However, it is likely that serology is more effective in the detection of specific antibodies against the Marseilleviridae family, as related in Gilbert Greub's work in this journal [21]. …”

“…Mimivirus seems to be linked to pneumonia and Marseillevirus is associated with asymptomatic carriage into blood [13] or in feces [22]. A case of adenitis in a young child has been identified [14] and antibodies to this virus have been found in blood donors [13,21]. …”