The use of ITS1 rDNA PCR in detecting pathogenic African trypanosomes

There are 11 different pathogenic trypanosomes in trypanosomiasis endemic regions of Africa. Their detection and characterisation by molecular methods relies on species-specific primers; consequently several PCR tests have to be made on each sample. Primers ITS1 CF and ITS1 BR, previously designed to amplify the internal transcribed spacer (ITS1) of rDNA, have been evaluated for use in a universal diagnostic test for all pathogenic trypanosomes. Blood was collected from 373 cattle and 185 camels. The primers gave constant PCR products with the stocks of each taxon tested. Members of subgenus Trypanozoon (T. brucei brucei, T. evansi, T. b. rhodesiense and T. b. gambiense) gave a constant product of approximately 480 bp; T. congolense, savannah 700 bp, T. congolense kilifi 620 bp and T. congolense forest 710 bp: T. simiae 400 bp, T. simiae tsavo 370 bp, T. godfreyi 300 bp and T. vivax 250 bp. The sensitivity of the test ranged from 10 pg for Trypanozoon, T. congolense clade and T. vivax to 100 pg for T. simiae and T. godfreyi. The primers detected cases of multi-taxa samples, although the sensitivity was reduced with an increase in the combinations. A better detection rate of trypanosome DNA was recorded with buffy coats than from direct blood. With the field samples, the diagnostic sensitivity was close to the sensitivity obtained using single reactions with species-specific primers for Trypanozoon 38/40 (95%) and T. congolense savannah 30/33 (90.9%) but was lower with T. vivax 25/31 (77.4%). The primers offer promise as a routine diagnostic tool through the use of a single PCR; however, further evaluation is recommended

Suscetibilidade de Trypanosoma evansi à anfotericina B Trypanosoma evansi susceptibility to amphotericin B

O objetivo deste estudo foi avaliar a suscetibilidade do Trypanosoma evansi in vitro e in vivo à anfotericina B. Nos testes in vitro, foram utilizadas quatro concentrações (0,06; 0,25; 1,0; 4,0µg mL-1) de anfotecicina B frente a uma suspensão de T. evansi em solução tampão fosfato rico em glicose (PBS - glicose). Para avaliar a eficácia in vivo, foram utilizados 15 ratos parasitados com T. evansi. Em dois grupos de cinco ratos infectados, doses únicas diárias de 1 (grupo A) e de 3mg kg-1 (grupo B) foram administradas via intraperitonial durante 10 dias, e a parasitemia foi avaliada por meio de esfregaço sanguíneo. Grupo C (n=5) foi utilizado como grupo controle positivo, infectados com T. evansi e não tratados, e o grupo D (n=5), como controle negativo. Os ensaios in vitro evidenciaram suscetibilidade de 100% do T. evansi à anfotericina B após 7h, em todas as concentrações avaliadas. Nos ratos, nem a maior dose testada curou os roedores, apesar de ter prolongado a vida destes em comparação à vida dos animais infectados, mas não tratados. Foi também investigada a função hepática e renal dos ratos após a terapia, e os parâmetros bioquímicos analisados mantiveram-se dentro da normalidade. Conclui-se que o T. evansi in vitro é suscetível à anfotericina B. A dose 3mg kg-1 testada aumentou a expectativa de vida de ratos infectados, porém não teve efeito curativo.<br>The aim of this study was to evaluate the Trypanosoma evansi susceptibility to amphotericin B in vitro and in vivo. Four concentrations (0.06, 0.25, 1.0, and 4.0µg mL-1) of amphotericin B were tested against a suspension containing T. evansi and phosphate buffer solution with glucose in the in vitro assay. Fifteen rats infected with T. evansi were used for the in vivo assay. Groups A (n=5) and B (n=5) received daily doses of 1 and 3mg kg-1 during 10 days and the parasitemia was estimated daily by microscopic examination of smears. The rats from group C (n=5) were the positive control and were infected but not treated. Rats from group D (n=5) were used as negative control. in vitro assays showed a 100% of susceptibility of T. evansi to amphotericin B after 7 hours, at all concentrations tested. The higher dose tested did not cure the rats, although treated rats had a longer life span in comparison to the non-treated group. Adverse effects on renal and hepatic hemodynamics were also researched. Biochemical parameters obtained were within the normal ranges. It was concluded that T. evansi is susceptible to amphotericin B in vitro. The dose of 3 mg kg-1 tested in rats increased life span, but did not cure the animals

Trypanosoma vivax infection dynamics in a cattle herd maintained in a transition area between Pantanal lowlands and highlands of Mato Grosso do Sul, Brazil Dinâmica de infecção de Trypanosoma vivax em rebanho bovino mantido numa área de transição entre o Pantanal e o planalto de Mato Grosso do Sul

Trypanosoma vivax outbreaks in beef cattle in the Pantanal region of Mato Grosso do Sul state, Brazil, causes relevant economical impact due to weight loss, abortion and mortality. Cattle moved from the Pantanal to adjacent areas of this ecosystem for breeding and fattening is a common feature. Therefore an epidemiological study on breeding cows in the transition area between Pantanal lowland and adjacent highlands of Mato Grosso do Sul was performed to determine the T. vivax infection dynamics and outbreak risk. Three experimental groups were formed: Group 1 consisted of cows parasitologically negative by the Woo test and in the enzyme-linked immunosorbent assay for T. vivax antibody detection (Tv-ELISA-Ab); Group 2 parasitologically negative and positive in the Tv-ELISA-Ab; and in Group 3 cows were parasitologically positive and with positive reactions in the Tv-ELISA-Ab. During 24 months, the cows' dislodgment between the above established groups was monitored by Woo test and Tv-ELISA-Ab exams. The tabanid population was also monitored and the highest number occurred during the rainy season. Although parasitemias were detected only in the first four samplings of the experimental period, the cows could be considered as trypanotolerant, because no clinical signs were observed. Despite the higher T. vivax incidence during the dry season, no disease symptoms were seen. Even though T. vivax epidemiological situation in the herd was characterized as endemic with seasonal variation, the probability of outbreaks was null within the conditions of the study.<br>Surtos de Trypanosoma vivax em bovinos de corte do Pantanal foram responsáveis por relevante impacto econômico, devido a perda de peso, abortos e mortalidade. Um manejo comum é o deslocamento de bovinos do Pantanal baixo para áreas adjacentes desse ecosistema para reprodução e engorda. Por essa razão, foi efetuado um estudo epidemiológico em rebanho de vacas movidas para uma área de transição entre Pantanal baixo e planalto do Estado de Mato Grosso do Sul para determinar a dinâmica de infecção do T. vivax e o risco de surto. Três grupos experimentais foram formados: Grupo 1; composto por vacas parasitologicamente negativas no teste de Woo e no exame sorológico de imunoadsorção enzimática para detecção de anticorpos contra T. vivax (Tv-ELISA-Ab); Grupo 2, vacas negativas parasitológicamente e com reação positiva no Tv-ELISA-Ab; e no Grupo 3, positivas parasitologicamente e no Tv-ELISA-Ab. Durante 24 meses o deslocamento das vacas entre esses grupos experimentais foi determinado pelo monitoramento mensal realizado pelo teste de Woo e Tv-ELISA-Ab. Durante esse período a população de tabanídeos na área experimental foi determinada e as maiores populações ocorreram no período das chuvas. Parasitemias de T. vivax foram detectadas apenas nas quatro primeiras amostragens do período experimental, apesar da elevação de incidência determinada sorológicamente tenha ocorrido no período seco do ano. Portanto, T. vivax foi endêmico no rebanho e a ausência de manifestação clínica sugere que os bovinos sejam tripanotolerantes e o risco de surto seja nulo nas condições em que o experimento foi executado, pois a manifestação clínica da doença esta associada à presença de parasitemia

2020 taxonomic update for phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales

In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV