Studies on the antigenic relationship among phleboviruses.

The antigenic relationship of the 31 currently recognized phlebotomus fever group viruses was examined by plaque reduction neutralization test. Although some low-level 0cross-neutralization was observed, each of the viruses was easily differentiated by this method. Rift Valley fever virus was shown to be antigenically related to Candiru, Frijoles, Karimabad and Punta Toro viruses. Naples, Tehran and Toscana viruses were also shown to be closely related. Preliminary results of indirect fluorescent antibody tests indicate that this technique is broadly reacting and less specific than either the complement-fixation or neutralization test for identifying phlebotomus fever group viruses. A discussion follows on some of the difficulties encountered in attempting to classify phleboviruses. Recently published reports" that Rift Valley infection has been demonstrated with seven other fever (RFV) virus is antigenically and biochemiPF group viruses (Arumowot, Bujaru, Gabek cally related to several viruses in the phlebotomus Forest, Gordil, Karimabad, Saint Floris and Tosfever group (family Bunyaviridae, genus Phlecana). .9 bovirus) have renewed interest in this little studied In 1975, Tesh et al. described the antigenic group of arthropod-borne viruses. The phlebotorelationship of 22 PF serotypes known at that mus fever (PF) group currently consists of 31 distime. By hemagglutination-inhibition (HI) test, trict virus serotypes (Table 1). These agents occur the viruses showed considerable cross-reactivity. in both the Old and New Worlds, and each seResults of complement-fixation (CF) and plaque rotype appears to have a different geographic disreduction neutralization (PRN) tests were more tribution. 3 In general their natural history is poorspecific, however, allowing clear separation of the ly understood. The majority have been associated various serotypes. 3 Since publication of the aforewith phlebotomine sandflies, . 4 but at least three mentioned data, nine additional virus serotypes of the serotypes (Arumowot, Itaporanga and Rift have been included in the PF group. In order to . Valley fever) appear to be mosquito-borne.' 5 Sevupdate these earlier serologic studies and to deJ en PF group viruses (Alenquer, Candiru, Chagres, termine the antigenic relationship of RVF virus, Naples, Punta Toro, Rift Valley fever and Sicilcross-neutralization tests were performed on the ian) have been isolated from sick persons.6 31 currently recognized Phlebovirus serotypes. SThree of these agents (Naples, Sicilian and Rift The present paper summarizes this work and also Valley fever) are of proven public health impordescribes preliminary studies on the use of imtance. In addition, serologic evidence of human munofluorescence to identify PF group viruses