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      Copro-PCR in the detection and confirmation of Toxoplasma gondii oocysts in feces of stray and domiciled cats Translated title: Copro-PCR na detecção e confirmação de oocistos de Toxoplasma gondii em fezes de gatos errantes e domiciliados

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          Abstract

          Abstract Molecular methods such as Copro-PCR stand out in the diagnosis of T. gondii, because they are highly sensitive and specific, and can distinguish T. gondii from other morphologically similar coccids. The purpose was the detection of Toxoplasma gondii copro-prevalence by polymerase chain reaction in 149 fecal samples from stray and domiciled cats, using three distinct markers (B5-B6, 18S and 529bp RE). Oocysts of T. gondii/H. hammondi were detected in 15.4% by parasitology fecal tests (PFT), and 4% of these oocysts were positively identified as T. gondii by Copro-PCR. The presence of T. gondii genetic material was detected in 16.1%, but 12% of the samples that tested positive by Copro-PCR were negative in PFT. Samples with discordant results were subjected to a new Copro-PCR with 18S marker and a 529, and of the 17 samples, 9 contained T. gondii genetic material. A comparison of the PFT and the molecular methods showed the latter was more sensitive, since it detected 22.1% while the PFT detected 15.4%. Demonstrating the high sensitivity and specificity of the Copro-PCR, particularly with the association of primers (k=0.809), but also confirms the importance of using molecular techniques in laboratories, since Copro-PCR was able to detect samples considered negative by PFT.

          Translated abstract

          Resumo Métodos moleculares como a Copro-PCR se destacam no diagnóstico de T. gondii por serem altamente sensíveis e específicos, podendo distinguir T. gondii de outros coccídeos morfologicamente semelhantes. O objetivo foi a detecção da coproprevalência de Toxoplasma gondii por reação em cadeia da polimerase, em 149 amostras fecais de gatos errantes e domiciliados, utilizando-se três marcadores distintos (B5-B6, 18S e 529pb RE). Oocistos de T. gondii/H. hammondi foram detectados em 15,4% pelos exames parasitológicos de fezes (EPF), e 4% desses oocistos foram identificados positivamente como T. gondii pela Copro-PCR. A presença de material genético de T. gondii foi detectada em 16,1%, mas 12% das amostras positivas pelo Copro-PCR foram negativas no EPF. As amostras com resultados discordantes foram submetidas a uma nova Copro-PCR com os marcadores 18S e 529 e, das 17 amostras, 9 continham material genético de T. gondii. A comparação do EPF com os métodos moleculares mostrou que esse último foi mais sensível, pois detectou 22,1%, enquanto o EPF detectou 15,4%. Isso demonstra a alta sensibilidade e especificidade da Copro-PCR, principalmente com a associação de marcadores (k = 0,809); mas também confirma a importância do uso de técnicas moleculares em laboratórios, uma vez que a Copro-PCR foi capaz de detectar amostras consideradas negativas pelo EPF.

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          Most cited references32

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          Toxoplasma gondii: from animals to humans

          Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii, is a facultatively heteroxenous, polyxenous protozoon that has developed several potential routes of transmission within and between different host species. If first contracted during pregnancy, T. gondii may be transmitted vertically by tachyzoites that are passed to the foetus via the placenta. Horizontal transmission of T. gondii may involve three life-cycle stages, i.e. ingesting infectious oocysts from the environment or ingesting tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals. Transmission may also occur via tachyzoites contained in blood products, tissue transplants, or unpasteurised milk. However, it is not known which of these routes is more important epidemiologically. In the past, the consumption of raw or undercooked meat, in particular of pigs and sheep, has been regarded as a major route of transmission to humans. However, recent studies showed that the prevalence of T. gondii in meat-producing animals decreased considerably over the past 20 years in areas with intensive farm management. For example, in several countries of the European Union prevalences of T. gondii in fattening pigs are now <1%. Considering these data it is unlikely that pork is still a major source of infection for humans in these countries. However, it is likely that the major routes of transmission are different in human populations with differences in culture and eating habits. In the Americas, recent outbreaks of acute toxoplasmosis in humans have been associated with oocyst contamination of the environment. Therefore, future epidemiological studies on T. gondii infections should consider the role of oocysts as potential sources of infection for humans, and methods to monitor these are currently being developed. This review presents recent epidemiological data on T. gondii, hypotheses on the major routes of transmission to humans in different populations, and preventive measures that may reduce the risk of contracting a primary infection during pregnancy.
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            Identification of a 200- to 300-fold repetitive 529 bp DNA fragment in Toxoplasma gondii, and its use for diagnostic and quantitative PCR.

            We have identified a novel 529bp fragment that is repeated 200- to 300-fold in the genome of Toxoplasma gondii. This 529bp fragment was utilised for the development of a very sensitive and specific PCR for diagnostic purposes, and a quantitative competitive-PCR for the evaluation of cyst numbers in the brains of chronically infected mice. The 529bp fragment was found in all 60 strains of T. gondii tested, and it discriminates DNA of T. gondii from that of other parasites. Toxoplasma gondii DNA was detected in amniotic fluid of patients, as well as in various tissues from infected mice. Polymerase chain reaction with the 529bp fragment was more sensitive than with the 35-copy B1 gene. For the quantitative competitive-PCR, a 410-bp competitor molecule was co-amplified with similar efficiency as the 529bp fragment. Quantitative competitive-PCR produced a linear relationship between the relative amounts of PCR product and the number of tachyzoites in the range of 10(2)-10(4) tachyzoites and 100-3000 tissue cysts. A highly significant correlation between visual counting of brain cysts and quantitative competitive-PCR was obtained in mice chronically infected with Toxoplasma. Thus, quantitative competitive-PCR with the 529bp fragment can be used as an alternative for the tedious visual counting of brain cysts in experimental animals. With the quantitative competitive-PCR, furthermore, we could confirm the copy number of the 529bp fragment in tachyzoites and estimate the number of bradyzoites per cyst.
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              Direct and sensitive detection of a pathogenic protozoan, Toxoplasma gondii, by polymerase chain reaction.

              We applied the polymerase chain reaction to detection of the pathogenic protozoan Toxoplasma gondii based on our identification of a 35-fold-repetitive gene (the B1 gene) as a target. Using this procedure, we were able to amplify and detect the DNA of a single organism directly from a crude cell lysate. This level of sensitivity also allowed us to detect the B1 gene from purified DNA samples containing as few as 10 parasites in the presence of 100,000 human leukocytes. This is representative of the maximal cellular infiltration (10(5)/ml) in 1 ml of cerebrospinal fluid obtained from patients with toxoplasmic encephalitis. The B1 gene is present and conserved in all six T. gondii strains tested to date, including two isolates from patients with acquired immunodeficiency syndrome. No signal was detected by using this assay and DNAs from a variety of other organisms, including several which might be found in the central nervous system of an immunocompromised host. This combination of sensitivity and specificity should make detection of the B1 gene based on polymerase chain reaction amplification a very useful method for diagnosis of toxoplasmosis both in immunocompromised hosts and in congenitally infected fetuses.
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                Author and article information

                Journal
                rbpv
                Revista Brasileira de Parasitologia Veterinária
                Rev. Bras. Parasitol. Vet.
                Colégio Brasileiro de Parasitologia Veterinária (Jaboticabal, SP, Brazil )
                0103-846X
                1984-2961
                2021
                : 30
                : 2
                : e000621
                Affiliations
                [02] Jataí Goiás orgnameUniversidade Federal de Goiás orgdiv1Unidade Acadêmica Especial de Saúde, Regional Jataí orgdiv2Laboratório de Bioquímica Clínica e Líquidos Corporais Brazil
                [01] Goiânia Goiás orgnameUniversidade Federal de Goiás orgdiv1Instituto de Patologia Tropical e Saúde Pública orgdiv2Laboratório de Estudos da Relação Parasito-Hospedeiro Brazil
                [03] Londrina Paraná orgnameUniversidade Estadual de Londrina orgdiv1Laboratório de Protozoologia Veterinária Brazil
                Article
                S1984-29612021000200301 S1984-2961(21)03000200301
                10.1590/s1984-29612021022
                b92d907e-b4c9-42a7-a942-94d9ffbe3a52

                This work is licensed under a Creative Commons Attribution 4.0 International License.

                History
                : 12 January 2021
                : 23 February 2021
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 32, Pages: 0
                Product

                SciELO Brazil

                Self URI: Full text available only in PDF format (EN)
                Categories
                Original Article

                Copro-PCR,Toxoplasma gondii,gatos,cats
                Copro-PCR, Toxoplasma gondii, gatos, cats

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