Rabies viruses circulating in Ceará, Brazil, were identified by molecular analysis to be related to variants maintained by dogs, bats, and other wildlife. Most of these viruses are associated with human rabies cases. We document the emergence of a rabies virus variant responsible for an independent epidemic cycle in the crab-eating fox (Cerdocyon thous).

Abstract. Twenty-eight samples from humans and domestic and wild animals collected in Mexico between 1990 and 1995 were characterized by using anti-nucleoprotein monoclonal antibodies and limited sequence analysis of the nucleoprotein gene. The variants of rabies viruses identified in these samples were compared with other isolates from Mexico and the rest of the Americas to establish epidemiologic links between cases and outbreaks and to increase the understanding of rabies epidemiology in the Western Hemisphere. Antigenic and genetic diversity was found in all samples from dogs and dog-related cases, suggesting a long-term endemic situation with multiple, independent cycles of virus transmission. Two isolates from bobcats were antigenically and genetically homologous to the rabies variant circulating in the Arizona gray fox population, indicating a wider distribution of this variant than previously reported. Rabies isolates from skunks were unrelated to any variant analyzed in this study and represent a previously unrecognized cycle of rabies transmission in skunks in Baja California Sur. Two antigenic and genetic variants cocirculating in southern and eastern Mexico were found in viruses obtained from cases epidemiologically related to vampire bats. These results serve as a baseline for the better understanding of the molecular epidemiology of rabies in Mexico.Urban and sylvatic rabies is an important public health and economic problem in Latin America. During the period 1990-1996, there were 1,372 human rabies cases in this region, but the animal responsible for the exposure was known for only 1,117 cases. The domestic dog and various Chiroptera species, mainly the vampire bat (Desmodus rotundus), were represented in 80.6% and 11.3% of these cases, respectively. 1 Urban rabies constitutes a dog-to-dog transmission cycle that is maintained in cities. Dogs are the primary source of infection for humans and other domestic animals. Rabies epidemiology is highly influenced by both human and dog population density and the cultural and socioeconomic factors that govern the interaction between those 2 populations. 2,3 These factors are particularly relevant in the case of Mexico. This country has one-fifth of the human population (approximately 93 million people) and one-fourth of the canine population (approximately 13.5 million dogs) of Latin America. 1,4 As a consequence of the implementation of an aggressive public health policy in Mexico for rabies control in the urban centers, there has been a substantial decrease in the number of canine rabies cases from 2,077 in 1992 to 521 in 1997. 5 Although the annual canine vaccine coverage in Mexico is approximate 78%, ultimate rabies control has been difficult to achieve. 4 Strategies for the application of control programs should involve careful planning based on the knowledge of the local epidemiologic situation. 6 The availability of detailed surveillance data, the identification of different transmission cycles, and the geographic distribution in urban settings are...

One hundred and five rabies isolates obtained from domestic animals and insectivorous bats in Chile between 1977 and 1998 were molecularly characterized by limited sequence analysis of their nucleoprotein genes. These isolates were compared with viruses isolated from known domestic and wildlife rabies reservoirs in the Americas to identify potential reservoirs of rabies in Chile. The phylogenetic analyses showed that none of the Chilean isolates segregated with viruses from the terrestrial reservoirs. No non-rabies lyssaviruses were found in this study. The Chilean samples were not related to viruses of the sylvatic cycle maintained by the common vampire bat (Desmodus rotundus) in Latin America. Five genetic variants were identified from insectivorous bats in Chile. The Brazilian free-tailed bat (Tadarida brasiliensis) was identified as the reservoir for the rabies genetic variant most frequently isolated in the country between 1977 and 1998. The close association of a group of viruses obtained from a domestic dog (Canis familiaris), Brazilian free-tailed bats, and a red bat (Lasiurus borealis) with viruses maintained by Lasiurus spp. in North America implicated species of this genus as the possible reservoirs of this particular genetic variant in Chile. Reservoirs for the other three variants remain unknown.

Twenty samples from cases of rabies in humans and domestic animals diagnosed in Venezuela between 1990 and 1994 and one sample from a vampire bat collected in 1976 were characterized by reactivity to monoclonal antibodies against the viral nucleoprotein and by patterns of nucleotide substitution in the nucleoprotein gene. Three antigenic variants were found: 1, 3, and 5. Antigenic variant 1 included all samples from dogs and humans infected by contact with rabid dogs. Unique substitutions permitted identification of two separate outbreaks of dog rabies in the Maracaibo Depression and Los Llanos region and in the Andean region of Venezuela. Samples from the vampire bat and two head of cattle were characterized as antigenic variant 3 and showed a nucleotide sequence homology of 96 to 98% to each other and to samples of vampire bat-associated rabies throughout Latin America. Ten of the remaining 12 samples were characterized as antigenic variant 5. Genetic studies indicated that 11 of these samples formed a highly homologous and distinctive group but were closely related to samples of vampire bat-associated rabies. The 12th sample of variant 5 (from a cat) showed only 78 to 80% genetic homology to samples of rabies associated with vampire bats. The application of antigenic and genetic typing to rabies surveillance in Latin America is essential to improve control programs. Recognition of the source of outbreaks of dog rabies and identification of wildlife species maintaining sylvatic cycles of rabies transmission permit better utilization of public health resources.

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Genome segment 2 (L2) from six field isolates of bluetongue virus (BTV) serotype 17 was sequenced by cycling sequencing after the amplification of the viral cDNA by the polymerase chain reaction. The viruses were isolated from sheep, cattle and a goat in the San Joaquin Valley of California during the years 1981 and 1990. These viruses exhibit divergent patterns of neutralization with BTV 17-specific monoclonal antibodies. The six L2 genes of the BTV 17 field isolates all encode a protein of 955 amino acids. Similarity of the nucleotide sequences of the L2 genes with respect to the prototype strain ranges between 93.8% and 95.1%, whereas the similarity between the field isolates ranges from 96.8% to 99.1%. Although very closely related, the L2 gene of each virus is distinct. Furthermore, mutations in the L2 gene of field isolates of BTV do not consistently follow a linear pattern of accumulation over time. Some amino acid changes in the VP2 protein of field strains were conserved over time, whereas others were not correlated with the year of isolation and some substitutions were unique to individual viruses. The predicted VP2s constitute a group of non-identical, but closely related proteins. Phylogenetic analyses suggest that the viral variants which co-circulate in the San Joaquin Valley could evolve by different evolutionary pathways.

Abstract. Genome segment 10 of bluetongue virus (BTV) serotype 11 UC8 strain was cloned and subsequently hybridized to viral double-stranded RNA extracted from 90 field isolates of BTV serotypes 10, 11, 13, and 17; the prototype strains of BTV 2, 10, 11, 13, and 17; the prototype strain epizootic hemorrhagic disease virus (EHDV) serotype 1; and 4 field isolates of EHDV serotype 2. The 90 field isolates were obtained from different counties in California, Louisiana, and Idaho during the years 1979, 1980, and 1981. The cloned genetic probe hybridized with all the BTV samples tested, showing different degrees of cross-hybridization at the stringency conditions used in this study. This indicated that BTV genome segment 10 has conserved nucleotide sequences among the BTV serotypes 2, 10, 11, 13, and 17. No cross-hybridization signals were detected between the cloned genome segment 10 of BTV 11 UC8 strain and the prototype strain of EHDV serotype 1 and the field isolates of serotype 2. This probe recognized a wide variety of BTV isolates.The genus Orbivirus of the family Reoviridae is divided into 12 serological groups, 2 of which are bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). Bluetongue virus and EHDV serogroups cross-react in some serological tests and are considered a cluster of viruses. 7 Bluetongue virus is the prototype virus of the genus Orbivirus and contains a genome of 10 double-stranded RNA (dsRNA) segments 24 that code for 10 viral polypeptides.The complete nucl e o t i d e s e q u e n c e s of R N A S l O o f BTV serotype 10 13 and Australian BTV serotype 1 8 have been determined. In both cases SlO consisted of 822 base pairs and showed regions of nucleic acid sequence conservation. 8 Molecular hybridization studies on the relationships between different strains and serotypes of BTV and EHDV have been done using RNA/RNA and DNA/RNA hybridization techniques. 2,6,9,10,12,18,19,23 It was demonstrated that BTV 10 SlO was conserved within all BTV serotypes, showing different degrees of cross-hybridization between them. 1o No important differences in hybridization were detected between virulent and avirulent BTV strains of the same serotype. 11 In interserogroup studies among EHDV, BTV, and pata virus no cross-hybridization between SlO was found. 2 We have cloned BTV 11 strain UC8 S10, which was isolated from a deer in the United States and showed a greater virulence in mice 27 than the prototype BTV 11 Station strain and BTV 11 UC2. Bluetongue virus 11 UC8 causes late-term abortion in cattle infected during the 8th month of pregnancy and severe neu- Received for publication October 31, 1988. ropathology in newborn mice. 26 The objectives of this study were to determine the feasibility of a recombinant complementary DNA (cDNA) probe from gene segment 10 of BTV 11 strain UC8 for identifying field isolates of BTV, and to study the degree of genetic relationship between S 10 of a virulent strain of BTV 11 with the BTV prototypes 2, 10, 11, 13, and 17; prototype EHDV 1; field isolates...