Patogenicidade e virulência de Toxoplasma gondii isolado de suínos de criação artesanal no sul do Brasil

Abstract

Estudos com Toxoplasma gondii em suínos são relevantes porque seus produtos e subprodutos fazem parte da cadeia alimentar do ser humano. As principais vias de transmissão deste agente são o carnivorismo, fecal-oral e congênita. Seis isolados de Toxoplasma gondii de suínos de criação artesanal foram avaliados quanto à patogenicidade e virulência em camundongos suíços albinos. A suspensão de taquizoítos utilizada nos testes foi obtida através da punção ou lavagem da cavidade peritoneal de camundongos que apresentaram ascite. Cada amostra foi inoculada em grupos de cinco camundongos, com inóculo de 10¹, 10², 10³, 10(4), 10(5) e 10(6) taquizoítos vivos, via intraperitoneal. Dos isolados, 50% (3/6) foram letais e causaram sinais clínicos nos camundongos. A dose mínima letal foi de 10³ taquizoítos. A morte dos animais que apresentaram infecção aguda ocorreu entre 12 e 26 dias após a inoculação. Todos os isolados da região estudada apresentam alta capacidade de formar cistos, o que pode aumentar o risco de infecção pela ingestão de tecidos dos animais infectados pelos mesmos.

Morphometric Analysis and Virulence of Isolates of Toxoplasma Gondii Recovered From Pregnant and Newborn Mice in Goiã‚nia-Go

“…10 . Samples of T. gondii have been differentiated through pathogenicity, which represents the capacity of the agent once into the host, of producing a variety of sign and symptoms and by its virulence , which is the capacity of the invader of producing pathological and even lethal effects 7 .…”

“…A differential pathogenicity and virulence or variation of T. gondii isolates were confirmed in the current study by observing differences in mortality rates of mice treated with different yet known amounts of tachyzoites in each one of the isolates. Differences in pathogenicity and virulence are more apparent in those cases in which dead of mice is observed directly as it is seen in the acute stage of the disease, or in those cases in which infected mice survive for a longer period of time as it occurs in the chronic form of the disease 7 . Noteworthy to mention is the role of the minimal inoculate of 10 x103 tachyzoites that was able to kill mice from isolate 3, which was considered the less virulent.…”

“…Samples of Toxoplasma gondii which have been isolated in humans, although apparently with a similar morphology, present biological, serological and immunological variations [5][6][7] . Differences in the antigenic profile of T. gondii have been described in isolated strains in a variety of hosts and also in intraspecific samples [5][6][7][8] . Major criteria to evaluate virulence of T. gondii strains are the percentages of mortality of mice infected with gradual inoculates of parasites as well as survival time of those that did not resist to that infection 5,8 .…”

“…Major criteria to evaluate virulence of T. gondii strains are the percentages of mortality of mice infected with gradual inoculates of parasites as well as survival time of those that did not resist to that infection 5,8 . Along these lines, most T.gondii strains have been defined as virulent, non virulent or with intermediate virulence depending on the morbidity and mortality in infected mice with that bacteria 4,[7][8][9] . The RH strain and those genetically similar strains, demonstrate a lethal dose of 100% (LD100) from only one viable parasite.…”