Transovarial transmission of African swine fever virus in the argasid tickOrnithodoros moubata

The aim of this study was to determine filial infection prevalence of exper imentally infected colony Ornithodoros moubata Walton (Ixodoidea: Argasidae ) ticks for African swine fever virus (ASFV). Three groups of ticks were us ed: an uninfected control group, one group orally infected with the VIC T90 /1 isolate and another group orally infected with the LIV 13/33 isolate of ASFV, The results show that filial infection prevalences were not constant but were highly variable between egg batches from different ticks and betwe en successive egg batches from the same tick. Filial infection prevalences ranged from 1.8% to 31.8% for ticks infected with the VICT90/1 isolate and from 1.2% to 35.5% for ticks infected with the LIV 13/33 isolate. A similar pattern was noted after the third feed. Immunohistochemisty showed that vi rus replicates in the developing larval cells and not in the yolk sac cells or within the outer layers of the eggs. The results show that ASFV can rep licate to a high titre (10(5.1)log(10)HAD(50)) within the larval cells of t he developing egg.