Atovaquone, chloroquine, primaquine, quinine and tetracycline: antiproliferative effects of relevant antimalarials on Neospora caninum / Atovaquona, cloroquina, primaquina, quinino e tetraciclina: efeitos antiproliferativos de antimaláricos relevantes em Neospora caninum

Abstract Neospora caninum is an apicomplexan parasite that causes abortion in cattle, resulting in significant economic losses. There is no commercial treatment for neosporosis, and drug repositioning is a fast strategy to test possible candidates against N. caninum. In this article, we describe the effects of atovaquone, chloroquine, quinine, primaquine and tetracycline on N. caninum proliferation. The IC50 concentrations in N. caninum were compared to the current information based on previous studies for Plasmodium and Toxoplasma gondii, correlating to the described mechanisms of action of each tested drug. The inhibitory patterns indicate similarities and differences among N. caninum, Plasmodium and T. gondii. For example, atovaquone demonstrates high antiparasitic activity in all the analyzed models, while chloroquine does not inhibit N. caninum. On the other hand, tetracycline is effective against Plasmodium and N. caninum, despite its low activity in T. gondii models. The repurposing of antimalarial drugs in N. caninum is a fast and inexpensive way to develop novel formulations using well-established compounds.

Resumo Neospora caninum é um parasita Apicomplexa relacionado a abortos no gado bovino, que resultam em impactos econômicos. Não há tratamento comercial para neosporosis e o reposicionamento de drogas indica uma estratégia rápida para testar candidatos anti-N. caninum. Neste artigo, são descritos os efeitos da atovaquona, cloroquina, quinino, primaquine e tetraciclina na proliferação de N. caninum. As concentrações IC50 em N. caninum foram comparadas com a informação disponível, baseada em estudos publicados previamente para Plasmodium e Toxoplasma gondii, incluindo a correlação com os mecanismos de ação descritos para cada droga testada. Os padrões de inibição indicam pontos de similaridades e diferenças entre N. caninum, Plasmodium e T. gondii. Por exemplo, a atovaquona demonstra uma alta atividade antiparasitária em todos os modelos testados, enquanto a cloroquina não inibe N. caninum. Por outro lado, a tetraciclina é efetiva contra Plasmodium e N. caninum, em contraste com a baixa atividade em modelos de T. gondii. O reposicionamento de drogas antimaláricas em N. caninum é uma forma rápida e de baixo custo para o desenvolvimento de novas formulações que usam compostos bem estabelecidos.

Efeitos in vitro e de 3-bromopiruvato e atovaquona na infecção por Toxoplasma gondii em células LLC-MK2 / Effect in vitro of 3-bromopyruvate and atovaquone on infection of toxoplasma gondii in llc-mk2 cells

Toxoplasma gondii causa uma infecção comumente assintomática, porémpode se apresentar de forma grave durante a gravidez e em pacientesimunocomprometidos. A terapia atual para a toxoplasmose é restrita contrataquizoítos, e possuem pouco ou nenhum efeito sobre bradizoítos, que são mantidosem cistos teciduais como fonte recrudescente da infecção. Com isso, novasalternativas terapêuticas vêm sendo propostas, como o uso da Atovaquona, queapresentou alguma eficácia sobre taquizoítos e bradizoítos em cistos teciduais.Neste trabalho, foi estudado o efeito de 3-BrPA, um composto utilizado em testessobre células cancerígenas, durante a interação de células LLC-MK2 infectadas comtaquizoítos da cepa RH de T. gondii. Quanto à célula hospedeira não se observouefeito do composto sobre a proliferação e viabilidade celular. A avaliação dainterferência de 3-BrPA sobre o crescimento in vitro do T. gondii evidenciou umaredução na proliferação intracelular do parasito de cerca de 55 por cento após 24 h detratamento e 61 por cento após 48 h. O desenvolvimento intracelular do parasito, analisadopor MEV, apresentou características morfológicas comumente encontradas emcistos teciduais. A incubação das culturas com lectina DBA confirmou odesenvolvimento de cistos e por MET se evidenciou a presença de bradizoítos. Alémdisso, foram revelados parasitos degradados e a influência do composto sobre aendodiogenia. Outra abordagem adotada foi o tratamento de culturas infectadas coma combinação de 3-BrPA e Atovaquona, que resultou em uma redução de parasitosintracelulares de 73 por cento após 24 h de tratamento e 71 por cento após 48 h, em comparação aocontrole, além da ausência da formação de parede cística nessas culturas...

Toxoplasma gondii usually causes an asymptomatic infection, but it can present severityduring pregnancy and in immunocompromised patients. Current therapies fortoxoplasmosis are restricted only against tachyzoites, and have little or no effect onbradyzoites, which are kept in tissue cysts like source of the infection recrudescent.Consequently, new therapeutic alternatives have been proposed, as the use ofAtovaquone that showed some efficacy against tachyzoites and bradyzoites in tissuecysts. In this work, we propose to study the effect of 3-BrPA, a compound that is beingtested against cancer cells, on the infection of LLC-MK2 cells with tachyzoites of T.gondii (RH strain). No effect of 3-BrPAon host cell proliferation and viability wasobserved. Evaluation of 3-BrPA interference on in vitro growth of T. gondii showed areduction in intracellular parasite proliferation about 55 por cento after 24 h of treatment, and61 por cento after 48 h. Intracellular development of parasite, analyzed by SEM, showedmorphological characteristics commonly found in tissue cysts. Incubation of cultureswith DBA lectin confirmed the development of cysts and TEM showed the presence ofbradyzoites. Moreover, we revealed the presence of degraded parasites and theinfluence of compound on endodyogeny. Another approach used was the treatment ofinfected cultures with combination of 3-BrPA and Atovaquone. This resulted in thereduction of intracellular parasites of 73 por cento after 24 h of treatment and 71 percent after 48 h,compared to control, besides the absence of cyst wall formation in these cultures...

An Imported Case of Severe Falciparum Malaria with Prolonged Hemolytic Anemia Clinically Mimicking a Coinfection with Babesiosis

While imported falciparum malaria has been increasingly reported in recent years in Korea, clinicians have difficulties in making a clinical diagnosis as well as in having accessibility to effective anti-malarial agents. Here we describe an unusual case of imported falciparum malaria with severe hemolytic anemia lasting over 2 weeks, clinically mimicking a coinfection with babesiosis. A 48-year old Korean man was diagnosed with severe falciparum malaria in France after traveling to the Republic of Benin, West Africa. He received a 1-day course of intravenous artesunate and a 7-day course of Malarone (atovaquone/proguanil) with supportive hemodialysis. Coming back to Korea 5 days after discharge, he was readmitted due to recurrent fever, and further treated with Malarone for 3 days. Both the peripheral blood smears and PCR test were positive for Plasmodium falciparum. However, he had prolonged severe hemolytic anemia (Hb 5.6 g/dl). Therefore, 10 days after the hospitalization, Babesia was considered to be potentially coinfected. A 7-day course of Malarone and azithromycin was empirically started. He became afebrile within 3 days of this babesiosis treatment, and hemolytic anemia profiles began to improve at the completion of the treatment. He has remained stable since his discharge. Unexpectedly, the PCR assays failed to detect DNA of Babesia spp. from blood. In addition, during the retrospective review of the case, the artesunate-induced delayed hemolytic anemia was considered as an alternative cause of the unexplained hemolytic anemia.

Compliance with Atovaquone-Proguanil against Malaria of Korean Travelers Abroad

BACKGROUND: Recently, many Korean people travel abroad where malaria is prevalent. However, in Korea, relatively little is known about compliance of chemoprophylaxis against malaria. This study was performed to determine the factors influencing compliance of chemoprophylaxis against malaria in Korean travelers. MATERIALS AND METHODS: Face to face interview, telephone interview and e-mail correspondence were performed to 241 people who were prescribed with atovaquone-proguanil at the international travelers' clinic of National Medical Center between February 2007 and October 2007. RESULTS: Total of 55 people out of 235 reported one or more events of adverse reactions after chemoprophylaxis (total 76 events). However, in 38 adverse events the link between chemoprophylaxis and adverse events were very weak. Compliance of malaria chemoprophylaxis with atovaquone-proguanil was 53.9% in the study group. The predictive factors for non-compliance were package tour, travel of business affair and young age group. Conclusions: Compliance of malaria chemoprophylaxis in Korea travelers was low compared with Dutch and French studies. More efforts to increase compliance are needed, especially in travelers on package tour, business travel and people under age 40.

Compliance with Atovaquone-Proguanil against Malaria of Korean Travelers Abroad

BACKGROUND: Recently, many Korean people travel abroad where malaria is prevalent. However, in Korea, relatively little is known about compliance of chemoprophylaxis against malaria. This study was performed to determine the factors influencing compliance of chemoprophylaxis against malaria in Korean travelers. MATERIALS AND METHODS: Face to face interview, telephone interview and e-mail correspondence were performed to 241 people who were prescribed with atovaquone-proguanil at the international travelers' clinic of National Medical Center between February 2007 and October 2007. RESULTS: Total of 55 people out of 235 reported one or more events of adverse reactions after chemoprophylaxis (total 76 events). However, in 38 adverse events the link between chemoprophylaxis and adverse events were very weak. Compliance of malaria chemoprophylaxis with atovaquone-proguanil was 53.9% in the study group. The predictive factors for non-compliance were package tour, travel of business affair and young age group. Conclusions: Compliance of malaria chemoprophylaxis in Korea travelers was low compared with Dutch and French studies. More efforts to increase compliance are needed, especially in travelers on package tour, business travel and people under age 40.

A Case of Human Babesiosis Confirmed by Polymerase Chain Reaction and Treated with Atovaquone and Azithromycin

Human babesiosis is a tick-borne infectious disease caused by Babesia species. The clinical diagnosis is difficult because of nonspecific symptoms like flu. Rapid diagnosis of human babesiosis is microscopic examination in peripheral blood smear (Giemsa-stain) which reveals characteristic forms of an intracellular quadruplet parasite. But differentiation between Babesia microti and Plasmodium species can be quite difficult because of the morphologic similarity. We experienced a case of human babesiosis. The patient was a 62-year old Korean male who had been in New Jersey, U.S.A for 2 months. We initially diagnosed as malaria infection because the peripheral blood smear revealed intracellular single ring form organism. But the patient was not improved significantly by the treatment with chloroquine regimen. Finally we confirmed human babesiosis by polymerase chain reaction for Babesia microti. We treated the patient successfully with a regimen of atovaquone and azithromycin which has fewer adverse reactions than a regimen of clindamycin and quinine.

A Case of Human Babesiosis Confirmed by Polymerase Chain Reaction and Treated with Atovaquone and Azithromycin

Human babesiosis is a tick-borne infectious disease caused by Babesia species. The clinical diagnosis is difficult because of nonspecific symptoms like flu. Rapid diagnosis of human babesiosis is microscopic examination in peripheral blood smear (Giemsa-stain) which reveals characteristic forms of an intracellular quadruplet parasite. But differentiation between Babesia microti and Plasmodium species can be quite difficult because of the morphologic similarity. We experienced a case of human babesiosis. The patient was a 62-year old Korean male who had been in New Jersey, U.S.A for 2 months. We initially diagnosed as malaria infection because the peripheral blood smear revealed intracellular single ring form organism. But the patient was not improved significantly by the treatment with chloroquine regimen. Finally we confirmed human babesiosis by polymerase chain reaction for Babesia microti. We treated the patient successfully with a regimen of atovaquone and azithromycin which has fewer adverse reactions than a regimen of clindamycin and quinine.

Pharmacokinetics of proguanil in malaria patients treated with proguanil plus atovaquone.

Clinical studies have shown atovaquone (ATQ), a new blood schizontocidal drug, in combination with proguanil (PROG) to be very effective in the treatment of acute multidrug-resistant falciparum malaria. The multiple dose pharmacokinetics of PROG were determined in Thai patients with acute falciparum malaria given PROG alone (200 mg PROG twice a day for 3 days, n = 4) and concurrently PROG and ATQ (200 mg PROG and 500 mg ATQ twice a day for 3 days, n = 12). There were no statistical differences (p > 0.05) in the area under the plasma drug concentration-time curve (AUC), apparent oral clearance (CL/F) and elimination half-life (t1/2) of PROG between patients given PROG alone and PROG/ ATQ. The median (range) kinetic values of PROG in patients given PROG alone and PROG/ATQ were respectively: CL/F = 1.25 l/h/kg (0.99-1.45) and 0.95 (0.73-1.32) l/h/kg, and t1/2 = 14.2 hours (9.3-16.8) and 13.6 hours (9.1-17.6). The CL/F and t1/2 of PROG in the Thai patients treated with the 2 treatment regimens were also comparable to values reported in healthy Thai volunteers given a standard prophylactic dose (200 mg PROG). The results of this preliminary study suggest that ATQ is unlikely to affect the pharmacokinetics of PROG to a clinically important extent at an ATQ dosage of 500 mg twice a day for 3 days in malaria infected patients.