Co-Circulation of Leishmania Parasites and Phleboviruses in a Population of Sand Flies Collected in the South of Portugal

In the Old World, phlebotomine sand flies from the genus Phlebotomus are implicated in the transmission of Leishmania spp. parasites (Kinetoplastida: Trypanosomatidae) and viruses belonging to the genus Phlebovirus (Bunyavirales: Phenuiviridae). Two of the five sand fly species known to occur in Portugal, Phlebotomus perniciosus and Ph. ariasi, the former being the most ubiquitous, are recognized vectors of Leishmania infantum, which causes visceral leishmaniasis, the most prevalent form of leishmaniasis in the country. Phlebotomus perniciosus is also the vector of the neurotropic Toscana virus, which can cause aseptic meningitis. Entomological surveillance is essential to provide fundamental data about the presence of vectors and the pathogens they can carry. As such, and given the lack of data in Portugal, an entomological survey took place in the Algarve, the southernmost region of the country, from May to October 2018. Polymerase chain reaction assays were performed in order to detect the presence of the above-mentioned pathogens in sand fly pools. Not only were both Leishmania parasites and phleboviruses detected during this study, but more importantly, it was the first time their co-circulation was verified in the same sand fly population collected in Portugal.

Phlebovirus diversity in ticks from livestock in arid ecologies in Kenya

Phleboviruses are emerging pathogens of public health importance. However, their association with ticks is poorly described, particularly in Africa. Here, adult ticks infesting cattle, goats and sheep were collected in two dryland pastoralist ecosystems of Kenya (Baringo and Kajiado counties) and were screened for infection with phleboviruses. Ticks mainly belonged to the species Rhipicephalus appendiculatus, Hyalomma impeltatum, and Hyalomma rufipes. A fragment of the RNA-dependent RNA polymerase (RdRp) gene was identified in thirty of 671 tick pools, of which twenty-nine were from livestock sampled in Baringo county. Phylogenetic analyses revealed that twenty-five sequences were falling in three clades within the group of tick-associated phleboviruses. The sequences of the three clades showed nucleotide distances 8%, 19% and 22%, respectively, to previously known viruses suggesting that these sequence fragments may belong to three distinct viruses. Viruses of the group of tick-associated phleboviruses have been found in several countries and continents but so far have not been associated with disease in humans or animals. In addition, five sequences were found to group with the sandfly-associated phleboviruses Bogoria virus, Perkerra virus and Ntepes virus recently detected in the same region. Further studies are needed to investigate the transmission and maintenance cycles of these viruses, as well as to assess their potential to infect vertebrates.

Geographic dispersal and genetic diversity of tick-borne phleboviruses (Phenuiviridae, Phlebovirus) as revealed by the analysis of L segment sequences

The large diversity of new tick-borne phleboviruses, and the negative impacts of the virulent viruses on human/animal health have led to a growing interest in their analysis. In this report, new insights are brought out into the diversity of putative phleboviruses circulating in Portugal (both the continental territory and the islands of São Miguel, in the Azores, and Madeira), as well as in the Spanish western regions of Extremadura and Castilla and León. Phlebovirus sequences were frequently detected (L-segment) from both questing and feeding ticks, but especially in Rhipicephalus sanguineus sensu lato (s.l.) specimens. These sequences were detected in adult ticks, as well as nymphs and eggs, supporting the hypothesis of viral maintenance by vertical transmission. Though multiple genetic groups could be identified in phylogenetic trees (AnLuc, KarMa, RiPar virus 1, and Spanish group 1 and 2), all the sequences from Portugal and Spain shared common ancestry with other viral sequence obtained from samples collected over a large geographic coverage. Spatiotemporal analysis placed Middle-East as the geographic origin of the most recent common ancestor (MRCA) of all phleboviruses analysed in the present study. More recent viral transitions might include migrations from Spain to continental Portugal, and from there to the Portuguese Islands. Our findings suggest that the time of the MRCA of phleboviruses was dated around 225 years ago [95% HPD: 124-387 year before the last sampling date].

The Prevalence of Antibodies against Sandfly Fever Viruses and West Nile Virus in Cyprus

BACKGROUND

Sandfly fever is an incapacitating disease caused by sandfly-borne Phleboviruses that can lead to meningitis, encephalitis or meningoencephalitis. West Nile virus (WNV), a mosquito-borne Flavivirus, can induce neuroinvasive disease manifested by meningitis, encephalitis or acute flaccid paralysis. Both vectors are endemic in Cyprus and very active during summer. The aims of this study were to determine first the prevalence of sandfly fever viruses (SFV) and WNV infections in Cyprus and second, to investigate their role in central nervous system (CNS) infections.

METHODS

For the prevalence study, 327 sera collected in 2013 and 2014 were tested for anti-SFV and anti-WNV IgG using indirect immunofluorescence assay and ELISA, respectively. In order to investigate a possible role of SFV and WNV in CNS infections, 127 sera of patients presenting symptoms of SFV or WNV infections were screened for IgM specific to SFV and WNV.

RESULTS

The overall anti-SFV IgG seroprevalence was 28% and was increasing with age (P< 0.01). The seroprevalence rate for anti-WNV IgG in Cyprus was 5%. Concerning the role of SFVs in CNS infections, anti-SFV IgM was detected in 8 out of 127 sera from selected patients presenting relevant symptoms of infections during vector's active period. In addition, anti-WNV IgM were detected in 17 out of the 127 patients with compatible symptoms.

CONCLUSION

The findings confirm the presence of sandfly fever and WNV in Cyprus and should, therefore, be considered in the differential diagnosis of patients with febrile illness/meningitis.

New bunya-like viruses: Highlighting their relations

The standard virus classification scheme for arenaviruses and bunyaviruses shifted dramatically when several groups reported the detection and isolation of divergent groups of viruses in a variety of insect collections. Although these viral families can differ in terms of morphology, structure and genetics, recent findings indicate these viruses may have a shared evolutionary origin. To determine the phylogenetic relations among these families, we inferred phylogenetic trees using three methods. The Maximum Likelihood and Bayesian trees were rooted as suggested by the (molecular clock-rooted) BEAST tree. Our results highlight a noteworthy relation among these viral supergroups of different genome organizations. Our study suggests that the best scenario is the existence of at least three monophyletic supergroups, all of them well supported. The recent data indicate that these viruses are evolutionarily and genetically interconnected. While these supergroups appear to be closely related in our phylogenetic analysis, other viruses should be investigated in future research. In sum, our results also provide insights into the classification scheme, thereby providing a new perspective about the fundamental questions of family origins, diversity and genome evolution.