Papers by Maria Jose Dus Santos
Journal of Clinical Virology Plus
Asymptomatic and presymptomatic patients played a critical role in the maintenance and spread of ... more Asymptomatic and presymptomatic patients played a critical role in the maintenance and spread of infection
during COVID pandemic. However, conflicting views about the infectiousness of asymptomatic patients have
been raised.
Identification of asymptomatic cases relies on SARS-CoV-2 genome detection and, in the absence of common
epidemiological variables, quantification of viral load (VL) has been proposed as an estimator for SARS-CoV-2
transmission.
Comparison of VLs from symptomatic and asymptomatic patients displayed variable results according to the
studied population, the experimental design and the sampling, among other variables.
The aim of this work was to determine VLs in symptomatic and asymptomatic patients at the time of sampling
and to retrospectively determine their relationship with severity of disease and other parameters that affected the
course of COVID-19, in two towns located in Buenos Aires, Argentina.
Results from our study showed that VLs from symptomatic and asymptomatic patients were significantly
different when analyzed globally. In addition, significant differences were found when VLs from each COVID-19
wave were analyzed. In the first wave VLs from asymptomatic patients (log10 8,21 gc/µl) were significantly
higher than in symptomatic ones (log10 6,51 gc/µl) while; in the second wave, VLs from asymptomatic patients
resulted significantly lower than in symptomatic patients (log10 4,51 gc/µl and log10 5,23 gc/µl, respectively).
In the third wave, no significant differences were observed between VLs from both types of patients.
Results from this work demonstrated that the screening of both symptomatic and asymptomatic patients was
of utmost importance in order to reduce SARS-CoV-2 transmission to communities.
Frontiers in Veterinary Science, 2022
SARS-CoV-2 reverse zoonosis, particularly to domestic animals, and the potential role of infected... more SARS-CoV-2 reverse zoonosis, particularly to domestic animals, and the potential role of infected animals in perpetuating the spread of the virus is an issue of increasing concern. In this case report, we identified the natural infection of two cats by SARS-CoV-2, in Argentina, whose owner had been previously infected by SARS-CoV-2. Viral genetic material was detected in feline oropharyngeal (OP) and rectal (R) swab by RT-qPCR, and sequence analysis revealed that the virus infecting the owner and one cat were genetically similar. The alpha variant (B.1.1.7 lineage) was identified with a unique additional mutation, strongly suggesting human-to-cat route of transmission. This study reinforces the One Health concept and the importance of integrating human, animal, and environmental perspectives to promptly address relevant health issues.
Ins crip ta co mo en ti dad de bien pú bli co por el Ministerio de Bie nes tar So cial de la Prov... more Ins crip ta co mo en ti dad de bien pú bli co por el Ministerio de Bie nes tar So cial de la Prov. de Bue nos Ai res con el Nº 1953/24/69. (Per so ne ría ju rí di ca Nº 876/64).
Bovine pestiviruses are the causative agents of Bovine viral diarrhea, a disease that generates s... more Bovine pestiviruses are the causative agents of Bovine viral diarrhea, a disease that generates severe economic losses in cattle. The aim of this study was to improve its diagnosis by means of developing a RT-qPCR to detect bovine pestiviruses A, B and H; and to set a protocol for collecting, shipping and conserving bovine pestiviral RNA in filter papers. The developed RT-qPCR showed high sensitivity in detecting these viruses in different matrixes: viral stocks, semen and serum samples. Regarding the possibility of using the technique to test serum pools, it was possible to identify a positive serum sample within a pool containing 30 sera. In addition to evaluating the qPCR from fresh samples, the use of filter papers to sow bovine samples was analyzed. The sampling method in two different filter papers using bovine blood drops was a useful alternative for diagnosis purposes and allowed the preservation of pestiviral RNA up to 12 months under refrigeration.
Frontiers in Medicine, 2021
SARS-CoV-2 variants with concerning characteristics have emerged since the end of 2020. Surveilla... more SARS-CoV-2 variants with concerning characteristics have emerged since the end of 2020. Surveillance of SARS-CoV-2 variants was performed on a total of 4,851 samples from the capital city and 10 provinces of Argentina, during 51 epidemiological weeks (EWs) that covered the end of the first wave and the ongoing second wave of the COVID-19 pandemic in the country (EW 44/2020 to EW 41/2021). The surveillance strategy was mainly based on Sanger sequencing of a Spike coding region that allows the identification of signature mutations associated with variants. In addition, whole-genome sequences were obtained from 637 samples. The main variants found were Gamma and Lambda, and to a lesser extent, Alpha, Zeta, and Epsilon, and more recently, Delta. Whereas, Gamma dominated in different regions of the country, both Gamma and Lambda prevailed in the most populated area, the metropolitan region of Buenos Aires. The lineages that circulated on the first wave were replaced by emergent variants ...
The deformed wing virus (DWV) is a highly prevalent pathogen that affects honeybees and is associ... more The deformed wing virus (DWV) is a highly prevalent pathogen that affects honeybees and is associated to colony losses. In Argentina, the Entre Rios province possesses a floral diversity that allows beekeepers to perform migratory or sedentary management. The aim of this work was to investigate the effect of both types of management on the prevalence and abundance of DWV and to characterize the DWV variant present in the study area. In migratory apiaries, 86.2% of the colonies gave a detectable result to DWV at the beginning of the season (September 2018), and 62% at the end of the season (April 2019). On the other hand, DWV was detected in 44.12% and 62% of sedentary samples, at the beginning and at the end of the season, respectively. The highest viral loads were obtained from migratory samples collected in September. DWV presence and abundance were associated with migratory management and the time of sampling. The virus was also detected in the brood, mites and pollen from the br...
Viruses
The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamm... more The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamma and Lambda variants. In this study, we aimed to describe the emergence and local genomic diversity of the SARS-CoV-2 Lambda variant in Argentina, from its initial entry into the country until its detection ceased. Molecular surveillance was conducted on 9356 samples from Argentina between October 2020 and April 2022, and sequencing, phylogenetic, and phylogeographic analyses were performed. Our findings revealed that the Lambda variant was first detected in Argentina in January 2021 and steadily increased in frequency until it peaked in April 2021, with continued detection throughout the year. Phylodynamic analyses showed that at least 18 introductions of the Lambda variant into the country occurred, with nine of them having evidence of onward local transmission. The spatial–-temporal reconstruction showed that Argentine clades were associated with Lambda sequences from Latin America a...
Viruses
The COVID-19 pandemic has lately been driven by Omicron. This work aimed to study the dynamics of... more The COVID-19 pandemic has lately been driven by Omicron. This work aimed to study the dynamics of SARS-CoV-2 Omicron lineages during the third and fourth waves of COVID-19 in Argentina. Molecular surveillance was performed on 3431 samples from Argentina, between EW44/2021 and EW31/2022. Sequencing, phylogenetic and phylodynamic analyses were performed. A differential dynamic between the Omicron waves was found. The third wave was associated with lineage BA.1, characterized by a high number of cases, very fast displacement of Delta, doubling times of 3.3 days and a low level of lineage diversity and clustering. In contrast, the fourth wave was longer but associated with a lower number of cases, initially caused by BA.2, and later by BA.4/BA.5, with doubling times of about 10 days. Several BA.2 and BA.4/BA.5 sublineages and introductions were detected, although very few clusters with a constrained geographical distribution were observed, suggesting limited transmission chains. The dif...
Veterinary Sciences
The honeybee Apis mellifera is highly appreciated worldwide because of its products, but also as ... more The honeybee Apis mellifera is highly appreciated worldwide because of its products, but also as it is a pollinator of crops and wild plants. The beehive is vulnerable to infections due to arthropods, fungi, protozoa, bacteria and/or viruses that manage to by-pass the individual and social immune mechanisms of bees. Due to the close proximity of bees in the beehive and their foraging habits, infections easily spread within and between beehives. Moreover, international trade of bees has caused the global spread of infections, several of which result in significant losses for apiculture. Only in a few cases can infections be diagnosed with the naked eye, by direct observation of the pathogen in the case of some arthropods, or by pathogen-associated distinctive traits. Development of molecular methods based on the amplification and analysis of one or more genes or genomic segments has brought significant progress to the study of bee pathogens, allowing for: (i) the precise and sensitiv...
Journal of Food Processing and Preservation, 2021
Propidium monoazide combined with a real-time polymerase chain reaction (PMA real-time PCR), is o... more Propidium monoazide combined with a real-time polymerase chain reaction (PMA real-time PCR), is one of the most promising methods to evaluate viable cells in food samples. The basic mechanism relies on the ability of PMA to penetrate compromised membranes of non-viable cells, given that when the cell membrane is intact, PMA is incapable to penetrate. A following photoactivation step converts the azido group of the PMA to a reactive nitrene radical which reacts with the double-stranded DNA and binds to it with high affinity (Taskin et al., 2011). This reaction inhibits PCR amplification of the modified DNA-targeted sequence (Nocker et al., 2006). This method offers several advantages over traditional techniques. It can determine viable counts faster than plate counting. In addition, produces less waste, it is more specific and less time consuming. Moreover, some authors have demonstrated that it is able to detect viable but not cultivable cells (
Los virus Hobi son un grupo de Pestivirus emergentes que afecta a bovinos y bubalinos y son conta... more Los virus Hobi son un grupo de Pestivirus emergentes que afecta a bovinos y bubalinos y son contaminantes muy comunes de productos biologicos. Luego de ser identificados por primera vez en Alemania a partir muestras brasileras en el ano 2004, han sido reportados numerosos aislamientos de virus Hobi en Brasil, Italia y algunos paises asiaticos. De este modo, este patogeno ha generado preocupacion en veterinarios y productores de rodeos bovinos y bubalinos al haber estado involucrado en eventos de cuadros respiratorios severos, abortos y animales persistentemente infectados. Debido a la falta de un sistema de vigilancia activo para estos nuevos patogenos, -y a que puede confundirse con Diarrea Viral Bovina-, no se conoce su verdadero impacto sobre las poblaciones bovinas. En Argentina, la presencia de los virus Hobi no ha sido estudiada, ni desde el punto de vista epidemiologico ni en cuanto a su potencial como agente adventicio en productos biologicos y lineas celulares. El objetivo ...
Molecular surveillance of SARS-CoV-2 variants was performed on a total of 2,406 samples from the ... more Molecular surveillance of SARS-CoV-2 variants was performed on a total of 2,406 samples from the capital city and nine provinces of Argentina, during 30 epidemiological weeks (EW) that covered the end of the first wave and the beginning of the ongoing second wave of the COVID-19 pandemic in the country (EW 44/2020 to EW 20/2021). The surveillance strategy was mainly based on Sanger sequencing of a Spike coding region that allows the simultaneous identification of signature mutations associated with worldwide circulating variants. In addition, whole SARS-CoV-2 genome sequences were obtained from 456 samples. The main variants found were Gamma, Lambda and Alpha, and to a lesser extent, Zeta and Epsilon. Whereas Gamma dominated in different regions of the country, both Gamma and Lambda prevailed in the most populated area, the metropolitan region of Buenos Aires (MABA), although showing a heterogeneous distribution along this region. This cost-effective surveillance protocol allowed fo...
Journal of Veterinary Diagnostic Investigation, 2017
HoBi-like pestiviruses (also known as bovine viral diarrhea virus 3) have been sporadically repor... more HoBi-like pestiviruses (also known as bovine viral diarrhea virus 3) have been sporadically reported from naturally infected cattle in Brazil, Asia, and Europe. Although HoBi-like viruses seem to be endemic in Brazilian cattle and buffalo, they have not been studied in the other countries of South America to our knowledge. Herein we report serologic results of buffalo from 12 large farms in Argentina located near the Brazilian border. These buffalo were not vaccinated against pestiviruses. Our results indicate that HoBi-like virus may be circulating in the northeastern region of Argentina given that half of the analyzed animals showed high levels of neutralizing antibodies against the pestivirus. The HoBi-like seropositive animals were also checked for neutralizing antibodies against BVDV-1a, BVDV-1b, and BVDV-2, and in most cases these animals had low levels or no detectable antibodies against these other pestiviruses. Our study suggests a need for continued pestivirus surveillance...
Veterinary research communications, Jan 7, 2016
Frontiers in Plant Science, 2015
Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decameric protein which can ac... more Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decameric protein which can accommodate foreign polypeptides or protein domains fused to its N-termini, markedly increasing their immunogenicity. The inner core domain (VP8d) of VP8 spike protein from bovine rotavirus is responsible for viral adhesion to sialic acid residues and infection. It also displays neutralizing epitopes, making it a good candidate for vaccination. In this work, the BLS scaffold was assessed for the first time in plants for recombinant vaccine development by N-terminally fusing BLS to VP8d and expressing the resulting fusion (BLSVP8d) in tobacco chloroplasts. Transplastomic plants were obtained and characterized by Southern, northern and western blot. BLSVP8d was highly expressed, representing 40% of total soluble protein (4.85 mg/g fresh tissue). BLSVP8d remained soluble and stable during all stages of plant development and even in lyophilized leaves stored at room temperature. Soluble protein extracts from fresh and lyophilized leaves were able to induce specific neutralizing IgY antibodies in a laying hen model. This work presents BLS as an interesting platform for highly immunogenic injectable, or even oral, subunit vaccines. Lyophilization of transplastomic leaves expressing stable antigenic fusions to BLS would further reduce costs and simplify downstream processing, purification and storage, allowing for more practical vaccines.
Plant Biotechnology Journal, 2015
SummaryVaccination has proved to be an efficient strategy to deal with viral infections in both h... more SummaryVaccination has proved to be an efficient strategy to deal with viral infections in both human and animal species. However, protection of cattle against viral infections is still a major concern in veterinary science. During the last two decades, the development of efficient plant‐based expression strategies for recombinant proteins prompted the application of this methodology for veterinary vaccine purposes. The main goals of viral bovine vaccines are to improve the health and welfare of cattle and increase the production of livestock, in a cost‐effective manner. This review explores some of the more prominent recent advances in plant‐made viral bovine vaccines against foot‐and‐mouth disease virus (FMDV), bovine rotavirus (BRV), bovine viral diarrhoea virus (BVDV), bluetongue virus (BTV) and bovine papillomavirus (BPV), some of which are considered to be the most important viral causative agents of economic loss in cattle production.
Veterinary Immunology and Immunopathology, 2009
Vaccine, 2005
The use of transgenic plants as vectors for the expression of viral and bacterial antigens has be... more The use of transgenic plants as vectors for the expression of viral and bacterial antigens has been increasingly tested as an alternative methodology for the production of experimental vaccines. Here, we report the production of transgenic alfalfa plants containing the genes encoding the polyprotein P1 and the protease 3C of foot and mouth disease virus (FMDV). The immunogenicity of the expressed products was tested using a mouse experimental model. Parenterally immunized mice developed a strong antibody response and were completely protected when challenged with the virulent virus. This report demonstrates the possibility of using transgenic plants to express polyprotein P1 and the protease 3C of FMDV and their utilization as effective experimental immunogens.
Journal of Virological Methods, 2009
Aim: The soluble isoform of the IFN-β receptor (sIFNAR2) can bind IFN-β and modulate its activity... more Aim: The soluble isoform of the IFN-β receptor (sIFNAR2) can bind IFN-β and modulate its activity, although its role in autoimmune diseases remains unknown. Methods: A recombinant human sIFNAR2 protein was cloned, expressed and purified after which we developed and validated an ELISA for its quantification in human serum. Serum sIFNAR2 were assessed in multiple sclerosis (MS) patients and healthy controls. Results: The ELISA has a dynamic range of 3.9-250 ng/ml and a detection limit of 2.44 ng/ml. Serum sIFNAR2 were significantly lower in untreated-MS patients than in healthy controls. Conclusion: The ELISA is suitable for quantification of sIFNAR2 in serum and should facilitate the study of sIFNAR2 in neuroimmunological diseases such as MS.
Veterinary Research Communications, 2009
Background: The cattle industry is one of the most important Brazilian agribusiness sectors and i... more Background: The cattle industry is one of the most important Brazilian agribusiness sectors and is a strong contributor to the national economy. Annually about 44.6 million calves are bred, which makes the optimal management of these animals extremely important. Several diseases can affect the initial stages of the bovine production chain, being the bovine respiratory syncytial virus (BRSV) one of the most relevant pathogens. This study aimed to characterize the epidemiology of BRSV infection in dairy cattle herds of São Paulo State, Brazil, using serological and risk factors analyses. For that, 1243 blood samples were collected of animals from 26 farms and a questionnaire about possible risk factors for BRSV prevalence was performed. The obtained blood sera were analyzed using virus neutralization test (VNT). Results: VNT results showed high BRSV prevalence in dairy cattle herds, reaching 79.5% of seropositivity. The BRSV seroprevalence among studied farms ranged from 40 to 100%. The analysis of risk factors indicated that the age group and the occurrence of coinfection with bovine herpesvirus 1 (BoHV-1) and bovine viral diarrhea virus 1 (BVDV-1) should be associated with a higher prevalence of BRSV, while natural suckling was considered a protective factor. Conclusions: The study showed that adult animals over 1 year old are an important risk factor for the high seroprevalence of BRSV in herds. The high BRSV prevalence associated with BoHV-1 and BVDV-1 suggests that biosecurity measures should be applied in order to reduce viral dissemination. Additionally, the natural suckling may be an important management to protect calves from high BRSV seroprevalence.
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Papers by Maria Jose Dus Santos
during COVID pandemic. However, conflicting views about the infectiousness of asymptomatic patients have
been raised.
Identification of asymptomatic cases relies on SARS-CoV-2 genome detection and, in the absence of common
epidemiological variables, quantification of viral load (VL) has been proposed as an estimator for SARS-CoV-2
transmission.
Comparison of VLs from symptomatic and asymptomatic patients displayed variable results according to the
studied population, the experimental design and the sampling, among other variables.
The aim of this work was to determine VLs in symptomatic and asymptomatic patients at the time of sampling
and to retrospectively determine their relationship with severity of disease and other parameters that affected the
course of COVID-19, in two towns located in Buenos Aires, Argentina.
Results from our study showed that VLs from symptomatic and asymptomatic patients were significantly
different when analyzed globally. In addition, significant differences were found when VLs from each COVID-19
wave were analyzed. In the first wave VLs from asymptomatic patients (log10 8,21 gc/µl) were significantly
higher than in symptomatic ones (log10 6,51 gc/µl) while; in the second wave, VLs from asymptomatic patients
resulted significantly lower than in symptomatic patients (log10 4,51 gc/µl and log10 5,23 gc/µl, respectively).
In the third wave, no significant differences were observed between VLs from both types of patients.
Results from this work demonstrated that the screening of both symptomatic and asymptomatic patients was
of utmost importance in order to reduce SARS-CoV-2 transmission to communities.
during COVID pandemic. However, conflicting views about the infectiousness of asymptomatic patients have
been raised.
Identification of asymptomatic cases relies on SARS-CoV-2 genome detection and, in the absence of common
epidemiological variables, quantification of viral load (VL) has been proposed as an estimator for SARS-CoV-2
transmission.
Comparison of VLs from symptomatic and asymptomatic patients displayed variable results according to the
studied population, the experimental design and the sampling, among other variables.
The aim of this work was to determine VLs in symptomatic and asymptomatic patients at the time of sampling
and to retrospectively determine their relationship with severity of disease and other parameters that affected the
course of COVID-19, in two towns located in Buenos Aires, Argentina.
Results from our study showed that VLs from symptomatic and asymptomatic patients were significantly
different when analyzed globally. In addition, significant differences were found when VLs from each COVID-19
wave were analyzed. In the first wave VLs from asymptomatic patients (log10 8,21 gc/µl) were significantly
higher than in symptomatic ones (log10 6,51 gc/µl) while; in the second wave, VLs from asymptomatic patients
resulted significantly lower than in symptomatic patients (log10 4,51 gc/µl and log10 5,23 gc/µl, respectively).
In the third wave, no significant differences were observed between VLs from both types of patients.
Results from this work demonstrated that the screening of both symptomatic and asymptomatic patients was
of utmost importance in order to reduce SARS-CoV-2 transmission to communities.