A phase I study to evaluate the safety, tolerance and pharmacokinetics of anti-Shiga toxin hyperimmune equine F (ab')2 fragments in healthy volunteers.

AIMS: Shiga toxin-producing Escherichia coli-haemolytic uraemic syndrome (STEC-HUS) is considered a toxaemic disorder in which early intervention with neutralizing antibodies may have therapeutic benefits. INM004, composed of F (ab')2 fragments from equine immunoglobulins, neutralizes Stx1/Stx2, potentially preventing the onset of HUS. METHODS: A single-centre, randomized, phase 1, single-blind, placebo-controlled clinical trial to evaluate INM004 safety, tolerance and pharmacokinetics (PK) in healthy adult volunteers, was conducted; in stage I, eight subjects were divided in two cohorts (n = 4) to receive a single INM004 dose of 2 or 4 mg kg-1, or placebo (INM004:placebo ratio of 3:1). In stage II, six subjects received three INM004 doses of 4 mg kg-1 repeated every 24 h, or placebo (INM004:placebo ratio of 5:1). RESULTS: Eight subjects (57.1%) experienced mild treatment-emergent adverse events (TEAEs); most frequent were rhinitis, headache and flushing, resolved within 24 h without changes in treatment or additional intervention. No serious AEs were reported. Peak concentrations of INM004 occurred within 2 h after infusion, with median Cmax values of 45.1 and 77.7 µg mL-1 for 2 and 4 mg kg-1, respectively. The serum concentration of INM004 declined in a biphasic manner (t1/2 range 30.7-52.9 h). Systemic exposures increased with each subsequent dose in a dose-proportional manner, exhibiting accumulation. Geometric median Cmax and AUC values were 149 and 10 300 µg h mL-1, respectively, in the repeated dose regimen. Additionally, samples from subjects that received INM004 at 2 mg kg-1 showed neutralizing capacity against Stx1 and Stx2 in in vitro assays. CONCLUSIONS: The results obtained in this first-in-human study support progression into the phase 2 trial in children with HUS.

Surveillance of Shiga toxin-producing Escherichia coli associated bloody diarrhea in Argentina.

In Argentina, hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC-HUS) infection is endemic, and reliable data about prevalence and risk factors have been available since 2000. However, information about STEC-associated bloody diarrhea (BD) is limited. A prospective study was performed during the period October 2018-June 2019 in seven tertiary-hospitals and 18 referral units from different regions, aiming to determine (i) the frequency of STEC-positive BD cases in 714 children aged 1-9 years of age and (ii) the rate of progression of bloody diarrhea to HUS. The number and regional distribution of STEC-HUS cases in the same hospitals and during the same period were also assessed. Twenty-nine (4.1%) of the BD patients were STEC-positive, as determined by the Shiga Toxin Quik Chek (STQC) test and/or the multiplex polymerase chain reaction (mPCR) assay. The highest frequencies were found in the Southern region (Neuquén, 8.7%; Bahía Blanca, 7.9%), in children between 12 and 23 month of age (8.8%), during summertime. Four (13.8%) cases progressed to HUS, three to nine days after diarrhea onset. Twenty-seven STEC-HUS in children under 5 years of age (77.8%) were enrolled, 51.9% were female; 44% were Stx-positive by STQC and all by mPCR. The most common serotypes were O157:H7 and O145:H28 and the prevalent genotypes, both among BD and HUS cases, were stx2a-only or -associated. Considering the endemic behavior of HUS and its high incidence, these data show that the rate of STEC-positive cases is low among BD patients. However, the early recognition of STEC-positive cases is important for patient monitoring and initiation of supportive treatment.

Safety and effectiveness of RBD-specific polyclonal equine F(ab´)2 fragments for the treatment of hospitalized patients with severe Covid-19 disease: A retrospective cohort study.

BACKGROUND: Passive immunotherapy has been evaluated as a therapeutic alternative for patients with COVID-19 disease. Equine polyclonal immunotherapy for COVID-19 (EPIC) showed adequate safety and potential efficacy in a clinical trial setting and obtained emergency use authorization in Argentina. We studied its utility in a real world setting with a larger population. METHODS: We conducted a retrospective cohort study at "Hospital de Campaña Escuela-Hogar" (HCEH) in Corrientes, Argentina, to assess safety and effectiveness of EPIC in hospitalized adults with severe COVID-19 pneumonia. Primary endpoints were 28-days all-cause mortality and safety. Mortality and improvement in modified WHO clinical scale at 14 and 21 days were secondary endpoints. Potential confounder adjustment was made by logistic regression weighted by the inverse of the probability of receiving the treatment (IPTW) and doubly robust approach. FINDINGS: Subsequent clinical records of 446 non-exposed (Controls) and 395 exposed (EPIC) patients admitted between November 2020 and April 2021 were analyzed. Median age was 58 years and 56.8% were males. Mortality at 28 days was 15.7% (EPIC) vs. 21.5% (Control). After IPTW adjustment the OR was 0.66 (95% CI: 0.46-0.96) P = 0.03. The effect was more evident in the subgroup who received two EPIC doses (complete treatment, n = 379), OR 0.58 (95% CI 0.39 to 0.85) P = 0.005. Overall and serious adverse events were not significantly different between groups. CONCLUSIONS: In this retrospective cohort study, EPIC showed adequate safety and effectiveness in the treatment of hospitalized patients with severe SARS-CoV-2 disease.

RBD-specific polyclonal F(ab´)2 fragments of equine antibodies in patients with moderate to severe COVID-19 disease: A randomized, multicenter, double-blind, placebo-controlled, adaptive phase 2/3 clinical trial.

BACKGROUND: passive immunotherapy is a therapeutic alternative for patients with COVID-19. Equine polyclonal antibodies (EpAbs) could represent a source of scalable neutralizing antibodies against SARS-CoV-2. METHODS: we conducted a double-blind, randomized, placebo-controlled trial to assess efficacy and safety of EpAbs (INM005) in hospitalized adult patients with moderate and severe COVID-19 pneumonia in 19 hospitals of Argentina. Primary endpoint was improvement in at least two categories in WHO ordinal clinical scale at day 28 or hospital discharge (ClinicalTrials.gov number NCT04494984). FINDINGS: between August 1st and October 26th, 2020, a total of 245 patients were enrolled. Enrolled patients were assigned to receive two blinded doses of INM005 (n = 118) or placebo (n = 123). Median age was 54 years old, 65•1% were male and 61% had moderate disease at baseline. Median time from symptoms onset to study treatment was 6 days (interquartile range 5 to 8). No statistically significant difference was noted between study groups on primary endpoint (risk difference [95% IC]: 5•28% [-3•95; 14•50]; p = 0•15). Rate of improvement in at least two categories was statistically significantly higher for INM005 at days 14 and 21 of follow-up. Time to improvement in two ordinal categories or hospital discharge was 14•2 (± 0•7) days in the INM005 group and 16•3 (± 0•7) days in the placebo group, hazard ratio 1•31 (95% CI 1•0 to 1•74). Subgroup analyses showed a beneficial effect of INM005 over severe patients and in those with negative baseline antibodies. Overall mortality was 6•9% the INM005 group and 11•4% in the placebo group (risk difference [95% IC]: 0•57 [0•24 to 1•37]). Adverse events of special interest were mild or moderate; no anaphylaxis was reported. INTERPRETATION: Albeit not having reached the primary endpoint, we found clinical improvement of hospitalized patients with SARS-CoV-2 pneumonia, particularly those with severe disease.

Development of a hyperimmune equine serum therapy for COVID-19 in Argentina.

The disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date. Equine polyclonal antibodies (EpAbs) put forward a sound alternative. The new generation of processed and purified EpAbs containing highly purified F(ab')2 fragments demonstrated to be safe and well tolerated. EpAbs are easy to manufacture allowing a fast development and scaling up for a treatment. Based on these ideas, we present a new therapeutic product obtained after immunization of horses with the receptor-binding domain of the viral Spike glycoprotein. Our product shows around 50 times more potency in in vitro seroneutralization assays than the average of convalescent plasma. This result may allow us to test the safety and efficacy of this product in a phase 2/3 clinical trial to be conducted in July 2020 in the metropolitan area of Buenos Aires, Argentina.

La enfermedad denominada COVID-19 es causada por el coronavirus SARS-CoV-2 y es actualmente considerada una pandemia a nivel global. El desarrollo de vacunas es sin duda la mejor estrategia a largo plazo, pero debido a la emergencia sanitaria, existe una necesidad urgente de encontrar soluciones rápidas y efectivas para el tratamiento de la enfermedad. Hasta la fecha, el uso de plasma de convalecientes es la única inmunoterapia disponible para pacientes hospitalizados con COVID-19. El uso de anticuerpos policlonales equinos (EpAbs) es otra alternativa terapéutica interesante. La nueva generación de EpAbs incluyen el procesamiento y purificación de los mismos y la obtención de fragmentos F(ab')2 con alta pureza y un excelente perfil de seguridad en humanos. Los EpAbs son fáciles de producir, lo cual permite el desarrollo rápido y la elaboración a gran escala de un producto terapéutico. En este trabajo mostramos el desarrollo de un suero terapéutico obtenido luego de la inmunización de caballos utilizando el receptor-binding domain de la glicoproteína Spike del virus. Nuestro producto mostró ser alrededor de 50 veces más potente en ensayos de seroneutralización in vitro que el promedio de los plasmas de convalecientes. Estos resultados nos permitirían testear la seguridad y eficacia de nuestro producto en ensayos clínicos de fase 2/3 a realizarse a partir de julio de 2020 en la zona metropolitana de Buenos Aires, Argentina.

Development of a hyperimmune equine serum therapy for COVID-19 in Argentina

The disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date. Equine polyclonal antibodies (EpAbs) put forward a sound alternative. The new generation of processed and purified EpAbs containing highly purified F(ab’)2 fragments demonstrated to be safe and well tolerated. EpAbs are easy to manufacture allowing a fast development and scaling up for a treatment. Based on these ideas, we present a new therapeutic product obtained after immunization of horses with the receptor-binding domain of the viral Spike glycoprotein. Our product shows around 50 times more potency in in vitro seroneutralization assays than the average of convalescent plasma. This result may allow us to test the safety and efficacy of this product in a phase 2/3 clinical trial to be conducted in July 2020 in the metropolitan area of Buenos Aires, Argentina.

La enfermedad denominada COVID-19 es causada por el coronavirus SARS-CoV-2 y es actualmente considerada una pandemia a nivel global. El desarrollo de vacunas es sin duda la mejor estrategia a largo plazo, pero debido a la emergencia sanitaria, existe una necesidad urgente de encontrar soluciones rápidas y efectivas para el tratamiento de la enfermedad. Hasta la fecha, el uso de plasma de convalecientes es la única inmunoterapia disponible para pacientes hospitalizados con COVID-19. El uso de anticuerpos policlonales equinos (EpAbs) es otra alternativa terapéutica interesante. La nueva generación de EpAbs incluyen el procesamiento y purificación de los mismos y la obtención de fragmentos F(ab’)2 con alta pureza y un excelente perfil de seguridad en humanos. Los EpAbs son fáciles de producir, lo cual permite el desarrollo rápido y la elaboración a gran escala de un producto terapéutico. En este trabajo mostramos el desarrollo de un suero terapéutico obtenido luego de la inmunización de caballos utilizando el receptor-binding domain de la glicoproteína Spike del virus. Nuestro producto mostró ser alrededor de 50 veces más potente en ensayos de seroneutralización in vitro que el promedio de los plasmas de convalecientes. Estos resultados nos permitirían testear la seguridad y eficacia de nuestro producto en ensayos clínicos de fase 2/3 a realizarse a partir de julio de 2020 en la zona metropolitana de Buenos Aires, Argentina.

Susceptibility of wild populations of Biomphalaria spp. from neotropical South America to Schistosoma mansoni and interference of Zygocotyle lunata.

Populations of Biomphalaria straminea, Biomphalaria peregrina , Biomphalaria tenagophila, Biomphalaria orbignyi, and Biomphalaria oligoza from different Argentine localities were exposed to miracidia of Schistosoma mansoni EC strain, and Biomphalaria tenagophila, in addition to the SJ2 strain. Biomphalaria straminea and B. tenagophila displayed different susceptibility and compatibility (Frandsen's total cercariae production index class 0-II), whereas B. orbigny and B. oligoza were incompatible. Although B. peregrina and B. tenagophila were found naturally infected with the amphistome Zygocotyle lunata, all 5 species could be experimentally infected with Z. lunata. Exposure to Z. lunata infections with S. mansoni were obtained in natural populations of B. straminea and B. tenagophila with the EC strain (13.5-17.1% and 1.2%), respectively, and in B. tenagophila with the SJ2 strain (2.6%), 60 days postexposure [PE]), and in B. orbignyi and B. oligoza (31.1% and 26.7% 60 days PE, respectively, including single infections with S. mansoni and double infections with Z. lunata). The high susceptibility of B. orbignyi and B. oligoza is noteworthy, as these 2 species are considered resistant to S. mansoni .

Analysis of the first and second internal transcribed spacer sequences of the ribosomal DNA in Biomphalaria tenagophila complex (Mollusca: Planorbidae).

The first and second internal transcribed spacer regions (ITS1 and ITS2) of the ribosomal DNA of Biomphalaria tenagophila complex (B. tenagophila, B. occidentalis, and B. t. guaibensis) were sequenced and compared. The alignment lengths of these regions were about 655 bp and 481 bp, respectively. Phylogenetic relationships among the Biomphalaria species were inferred by Maximum Parsimony and Neighbor-joining methods. The phylogenetic trees produced, in most of the cases, were in accordance with morphological systematics and other molecular data previously obtained by polymerase chain reaction and restriction fragment length polymorphism analysis. The present results provide support for the proposal that B. tenagophila represents a complex comprising B. tenagophila, B. occidentalis and B. t. guaibensis.

Analysis of the first and second internal transcribed spacer sequences of the ribosomal DNA in Biomphalaria tenagophila complex (Mollusca: Planorbidae)

The first and second internal transcribed spacer regions (ITS1 and ITS2) of the ribosomal DNA of Biomphalaria tenagophila complex (B. tenagophila, B. occidentalis, and B. t. guaibensis) were sequenced and compared. The alignment lengths of these regions were about 655 bp and 481 bp, respectively. Phylogenetic relationships among the Biomphalaria species were inferred by Maximum Parsimony and Neighbor-joining methods. The phylogenetic trees produced, in most of the cases, were in accordance with morphological systematics and other molecular data previously obtained by polymerase chain reaction and restriction fragment length polymorphism analysis. The present results provide support for the proposal that B. tenagophila represents a complex comprising B. tenagophila, B. occidentalis and B. t. guaibensis.

Characterization of Biomphalaria orbignyi, Biomphalaria peregrina and Biomphalaria oligoza by polymerase chain reaction and restriction enzyme digestion of the internal transcribed spacer region of the RNA ribosomal gene

The correct identification of Biomphalaria oligoza, B. orbignyi and B. peregrina species is difficult due to the morphological similarities among them. B. peregrina is widely distributed in South America and is considered a potential intermediate host of Schistosoma mansoni. We have reported the use of the polymerase chain reaction and restriction fragment length polymorphism analysis of the internal transcribed spacer region of the ribosomal DNA for the molecular identification of these snails. The snails were obtained from different localities of Argentina, Brazil and Uruguay. The restriction patterns obtained with MvaI enzyme presented the best profile to identify the three species. The profiles obtained with all enzymes were used to estimate genetic similarities among B. oligoza, B. peregrina and B. orbignyi. This is also the first report of B. orbignyi in Uruguay

Genetic variability and identification of the intermediate snail hosts of Schistosoma mansoni

Studies based on shell or reproductive organ morphology and genetic considerations suggest extensive intraspecific variation in Biomphalaria snails. The high variability at the morphological and genetic levels, as well as the small size of some specimens and similarities between species complicate the correct identification of these snails. Here we review our work using methods based on polymerase chain reaction (PCR) amplification for analysis of genetic variation and identification of Biomphalaria snails from Brazil, Argentina, Uruguay and Paraguay. Arbitrarily primed-PCR revealed that the genome of B. glabrata exhibits a remarkable degree of intraspecific polymorphism. Low stringency-PCR using primers for 18S rRNA permited the identification of B. glabrata, B. tenagophila and B. occidentalis. The study of individuals obtained from geographically distinct populations exhibits significant intraspecific DNA polymorphism, however specimens from the same species, exhibit some species specific LSPs. We also showed that PCR-restriction fragment of length polymorphism of the internal transcribed spacer region of Biomphlaria rDNA, using Ddel permits the differentiation of the three intermediate hosts of Schistosoma mansoni. The molecular biological techniques used in our studies are very useful for the generation of new knowledge concerning the systematics and population genetics of Biomphalaria snails.