Influence of feeding and starvation on the persistence and transmission of Quaranfil virus by Argas (Persicargas) arboreus (Acari: Argasidae)

Viral antigen was detected in the cytoplasm and in associated membranes of salivary gland acinus cells by indirect immunofluorescence and immunoperoxidase staining. Viral ribonucleoproteins (indicated histochemically by presence of pyroninophilic granules) which had accumulated in the cytoplasm of salivary gland type B (granular) acini of unfed Argas (Persicargas) arboreus Kaiser, Hoogstraal & Kohls were no longer visible 24 h after feeding. Virus in tick salivary glands increased from 300 to 500 plaque-forming units during the brief feeding interval (approximately 1 h), but virus was not detectable by 72 h. Overall salivary gland, ovarian, and synganglion tissue levels of Quaranfil virus decreased in the 96 h after feeding, except for synganglion samples in which virus titers increased during 24 h after feeding. Starvation for 105 d resulted in a sevenfold increase in salivary gland viral content compared with those starved 45 d, whereas synganglion tissue titers for Quaranfil virus became undetectable, and ovarian tissue values were similar to those starved for 45 d. Feeding had a greater effect on viral persistence in tissues for ticks starved 60 additional d (comparing 45 with 105 d) in that no Quaranfil virus was detected in any tissue after 48 h (compared with 72 h). Feeding infected ticks (with short extrinsic incubation) on chicks resulted in a peak of host mortality on days 7 and 8, whereas long extrinsic incubation resulted in sporadic mortality over 20 d of monitoring.