Neutralization-based seroprevalence of Toscana virus and sandfly fever Sicilian virus in dogs and cats from Portugal

Abstract

Sandfly-borne phleboviruses are endemic in the Mediterranean basin. However, levels of exposure of human and animal populations are inadequately researched. Toscana virus (TOSV) is present in Portugal where it causes human infection and disease; in contrast there are few data for sandfly fever Sicilian virus (SFSV) which has neither been isolated nor detected by molecular tests and for which there are only limited serological data. The sera collected from 1160 dogs and 189 cats in southern Portugal were tested for the presence of neutralizing antibodies against TOSV and SFSV, two viruses recognized as distinct serocomplexes in the Mediterranean region. Our data showed (i) seropositivity to TOSV and SFSV in dogs at a rate of 6.8 and 50.8 %, respectively, and (ii) that 3.7 % of cats were seropositive for TOSV. TOSV findings are in line with previous results obtained with less stringent serological assays. Our results for SFSV in dogs clearly indicate that the virus is circulating widely and that humans may be exposed to infection via the dogs. Although the presence of SFSV was suggested by haemagglutination inhibition in 4/1690 human sera in 1974, this is the first time, as far as we know, that SFSV has been shown to circulate so widely in dogs in Portugal. Future studies should be directed at isolating strains of SFSV in Portugal from dogs, humans and sandflies collected in high prevalence regions. As dogs appear to be good sentinels for SFSV, their role as a possible reservoir in the natural cycle should also be considered.

High Rates of Neutralizing Antibodies to Toscana and Sandfly Fever Sicilian Viruses in Livestock, Kosovo

“…Neutralizing antibody–based seroprevalence studies using animal serum proved interesting regarding the global circulation of corresponding viruses, as recently described in Portugal, Tunisia, and Greece ( 7 – 9 ). To improve understanding of the circulation of TOSV and SFSV in Kosovo, we tested serum samples collected in cattle and sheep through neutralizing assay and field-trapped sand flies for viral RNA.…”

“…We tested cattle and sheep serum for neutralizing antibodies using the virus microneutralization assay, described for phleboviruses ( 7 ) in parallel with TOSV strain MRS2010-4319501 and SFSV strain Sabin. Serum samples were diluted from 1:10 to 1:80 into 96-well plates with a volume of 50 μL.…”

“…Although no direct evidence (molecular detection of viral RNA or virus isolation) exists of SFSV or another SFSV-like virus in Kosovo or neighboring countries, our results imply the presence of either SFSV or an SFSV-related virus in Kosovo. We consider it valid to use SFSV as a surrogate for all SFSV-related viruses (sandfly fever Turkey virus, sandfly fever Cyprus virus) because amino acid distances observed between the proteins that elicit neutralizing antibodies (Gn and Gc) are well within the acceptable range, (i.e., <5% different for SFSV and SFSV-related viruses) ( 7 ). Thus, neutralizing antibodies are unlikely to discriminate between closely related SFSV isolates.…”

“…Recent seroprevalence studies showed high seroprevalence rates for SFSV neutralizing antibodies in dogs in Portugal (50.8%) ( 7 ), Tunisia (38.1%–59.2% depending on the region) ( 8 ), and Greece (71.9%) and Cyprus (60.2%) ( 11 ) . Our results are congruent with data from continental Greece, with rates in the same order of magnitude ( 12 ).…”

Monitoring Leishmania infection and exposure to Phlebotomus perniciosus using minimal and non-invasive canine samples

“…Whenever available, data on sex, breed, coat length, coat colour, age, use of insecticides and presence of clinical signs compatible with leishmaniosis (namely muscular atrophy, cutaneous lesions, epistaxis, lameness, lymphadenomegaly, onychogryphosis, ocular lesions, pale mucous membranes or weight loss; [20]) were recorded for each dog. Blood and serum samples were obtained from previous epidemiological studies regarding exposure to L. infantum or Toscana and sand fly fever Sicilian viruses [21][22][23][24].…”