Efficacy of leptospiral commercial vaccines on the protection against an autochtonous strain recovered in Brazil

Abstract

In swine and bovines, leptospirosis prevention and control is carried out via vaccination of susceptible animals using bacterins. However, the efficiency of leptospirosis vaccines has been questioned. This work aimed to investigate the potency of five leptospirosis vaccines sold commercially in Brazil, challenging the animals with one autochthonous strain of Leptospira, Canicola serovar, denoted LO4, isolated from swine. The standard protocol was followed, and renal carriers of Leptospira were identified among the surviving animals by culture and PCR. Of the five vaccines tested, only two proved effective. None of the surviving animals was positive by culture; however, one animal was positive by PCR. Three of the five vaccines sold commercially in Brazil for the immunization of swine or bovines failed the test of the efficacy to protect the vaccinated animals following challenge with an autochthonous Leptospira strain, Canicola serovar. The two vaccines provided protection against the renal carrier state in the surviving animals. The criteria used to produce leptospirosis bacterins sold commercially in Brazil must be reviewed. The industry should support researches on leptospiral vaccinology to improve the quality of the present vaccines and discover new immunogenic strains, because it is known that vaccination is one of the most important tools to increase the reproduction rates in livestock.

A live attenuated-vaccine model confers cross-protective immunity against different species of the Leptospira genus

“…Other than reduction of lethality, the ability to prevent transmission is a key parameter to determine the success and feasibility of a leptospiral vaccine. Whole-cell vaccines have shown divergent levels of protection against colonization in different species ( Sonada et al, 2018 ; Murray et al, 2013 ; Clough et al, 2018 ; Bolin and Alt, 2001 ). In our hamster model we observed a significant reduction of the bacterial burden in the kidney of vaccinated animals, without significant levels of protection.…”

A Live Attenuated Vaccine Model Confers Cross-Protective Immunity Against Different Species ofLeptospiraspp.

“…Other than reduction of lethality, the ability to prevent transmission is a key parameter to determine the success and feasibility of a leptospiral vaccine. Whole-cell vaccines have shown divergent levels of protection against colonization in different species 26-29 . In our hamster model we observed a significant reduction of the bacterial burden in the kidney of vaccinated animals, without significant levels of protection.…”

Leptospira in livestock in Madagascar: uncultured strains, mixed infections and small mammal-livestock transmission highlight challenges in controlling and diagnosing leptospirosis in the developing world

“…The identification of strains in Madagascar, Tanzania, Reunion and Brazil, such as L. borgpetersenii clade D (Figure 2), genetically distinct from any reference strains, has implications for the control and diagnosis of leptospirosis in the developing world. In Brazil, it has been demonstrated that the efficacy of commercial vaccines is poor in the face of autochthonous strain challenge (Sonada et al, 2018) and it is likely that commercial vaccines are likely to perform as poorly in Madagascar and other developing countries. Moreover, the inclusion of local isolates in antigen panels for serological assays, such as MAT, can dramatically increase the serological detection of infections (Mgode et al, 2015).…”

“…Vaccination of livestock is used to both improve productivity and to reduce zoonotic risk from livestock (Marshall and Chereshsky, 1996). However, recent studies have demonstrated that commercial leptospirosis vaccines may lack efficacy when challenged by autochthonous livestock strains in Brazil (Sonada et al ., 2018) and will not reduce human infections from serovars associated with wildlife (Thornley et al ., 2002). Therefore, to inform control measures, we used abattoir sampling and molecular methods to determine the prevalence and diversity of Leptospira in livestock in Madagascar and their phylogenetic relationship to Leptospira identified in livestock from similar studies in other developing countries.…”