Phylogenetic analysis of rabies viruses isolated from cattle in southern Brazil

Abstract

Bats and dogs are the main reservoirs of rabies virus (RABV) in Latin America and are responsible for the maintenance of different cycles of infection. In the two neighbour and most southern Brazilian states of Rio Grande do Sul (RS) and Santa Catarina (SC), rabies in dogs has been successfully controlled for more than 30 years. However, rabies associated to the rural cycle remains endemic, with a significant, though oscillating-annual incidence of rabies in cattle. Despite the plethora of studies on genetic analyses of Brazilian RABV, isolates from southern Brazil have only scarcely been investigated. This work was performed to identify the genetic lineages of RABVs circulating in states of RS and SC. Fifty-nine RABV cattle isolates from RS and SC were selected and submitted to reverse transcription/polymerase chain reaction (RT-PCR) followed by sequencing of the nucleoprotein gene. In RS, the circulation of two sublineages (1A and 1B) of RABV was detected, both with characteristics of lineages usually detected in vampire bats (Desmodus rotundus). In SC, only one sublineage of RABV (1B) was detected. Nevertheless, the findings reported here are expected to contribute to the understanding of the biology of the virus in the region and its interactions with the natural host D. rotundus. Keywords Rural rabies • Genetic lineages • Rio Grande do Sul • Santa Catarina • BrazilEdited by Zhen F. Fu.

Viral diseases of sheep in Brazil: a review and current status

“…In subcluster 1B along with isolates from Southern Brazil, sequences corresponding to viruses recovered from GenBank isolated from Uruguay and Argentina were grouped together. Also, sublineage 1A seems to have a wider geographic distribution than sublineage 1B (FERNANDES et al, 2020).…”

“…Although, unofficial, immunohistochemistry (IHC) is also a valuable tool for confirming cases where there is not an available refrigerated brain sample (Figure 2D) (RISSI et al, 2010b;BASSUINO et al, 2016). Although is not officially used for routine, realtime RT-PCR can be employed in diagnosing rabies (FERNANDES et al, 2020).…”

“…These data provide the base for planning control measures, such as vaccination implementation and control of rabies in wildlife, including the elimination of reservoir species. Since in Brazil, the distribution of livestock cases is frequently related to the presence of Desmodus rotundus populations, the main reservoir and source of infection for livestock, the identification of these species foci is essential to determine where control measures must be implemented (FERNANDES et al, 2020).…”

Phylogenetic relationship of rabies virus (Rabies lyssavirus) in two different host species

“…As D. rotundus feeds preferentially on the blood of cattle, the introduction and dissemination of herds provided food resources widely available in several regions of South America, which have potential for livestock production. In this way, the endemic character of rabies in cattle is maintained, giving rise to sporadic outbreaks of the disease [23]. When interventions such as vaccination and surveillance are not implemented or are not successful, the virus can establish itself in a new host [22].…”

Regulation of innate immune responses by rabies virus

“…It has been a global concern because after the symptoms of rabies appear, the mortality rate is close to 100%, and it ultimately leads to death; only a very few cases survive with serious sequelae.Although prevention and control of rabies has greatly improved globally and rabies cases are extremely rare in developed countries and regions, 1,2 it is still at a high level in many developing countries and less-developed countries, mainly concentrated in Africa and Asia. [3][4][5][6][7][8][9][10][11][12][13][14][15] According to the World Health Organization report in 2017, about 59 000 people die of rabies every year. Except for vaccination and emergency treatment with a specific antiserum after exposure, [16][17][18] there are no effective drugs for rabies.…”