RESUMEN

BACKGROUND: Human parvovirus B19V is a DNA virus, and a member of the family Parvoviridae, that causes various clinical manifestations, from asymptomatic to persistent infection that is associated with different autoimmune diseases. The parvovirus B19 evolves with a very high mutation rate that is closer to those of existing RNA viruses. Globally circulating B19V is currently classified into three genotypes, but their distribution is not spatially and temporally correlated. Except for a few recent reports on B19V entry into the human host and its genetic diversity, there is a lack of sufficient studies on this virus from distinct geographical locations and no clear understanding of its evolution has been documented. METHODS: To better understand the evolution of the Human parvo B19V virus from India's southern part, a geographically distinct location with no reports of B19V genomes, we have screened for B19V in 456 suspected cases using VP1/2 surface marker genes, and its characteristics were studied in detail. Amongst 456 clinically suspected B19V samples, 7.2% (33/456) were found positive by nested PCR (nPCR) were subsequently validated by real-time PCR, Sanger sequencing, and metagenome analysis. RESULTS: Human parvovirus B19 infection was shown among 33 of 456 patients when tested by nPCR; 30 among these were also positive by qPCR and were subsequently confirmed by sequencing 75% nPCR positive samples and 76% qPCR positive samples were from patients with age. ≥ 50 years respectively (Additional file 1: Table S1). The complete VP1/2 gene assembly from the South Indian strain showed three novel mutations (T122A, V128I, I283V), which might significantly impact the stability and virulence of the B19V virus circulating in this part of the world. These mutations might be crucial for its adaptive evolutionary strategies facilitating the spread and infectivity potential of the virus. In maximum likelihood phylogeny of VP1/2 sequences, the South Indian B19V strain forms a separate clade closer to the existing genotype two strains circulating worldwide. CONCLUSION: Our study contributes to a better understanding of the human parvovirus's genetic and evolutionary characteristics in South India. Also, it highlights the possibility that a positive selection pressure acting on VP1/2 could increase the survival and replication capabilities of the viruses.

Asunto(s)

Infecciones por Parvoviridae , Parvovirus B19 Humano , Anticuerpos Antivirales , ADN Viral/genética , Humanos , India/epidemiología , Infecciones por Parvoviridae/epidemiología , Parvovirus B19 Humano/genética , Parvovirus B19 Humano/inmunología , Infección Persistente , Reacción en Cadena en Tiempo Real de la Polimerasa

RESUMEN

PURPOSE OF REVIEW: Acute respiratory infections caused by influenza virus are a major cause of viral respiratory diseases globally. Surveillance of circulating subtypes and estimation of disease burden is of utmost clinical importance. Molecular surveillance and proper disease burden estimates are scarce in India although clinical influenza infections are on the rise. Our study aims to delineate the prevalent influenza subtypes in a South Indian population from cases requiring hospital visits. Using real-time polymerase chain reaction (RT-PCR), 2154 throat/nasopharyngeal swabs from patients attending Government Medical College, Thiruvananthapuram, Kerala, India, with suspected influenza-like illness, were tested for the presence of different influenza subtypes. RESEARCH FINDINGS: Forty-three percent of specimens were positive for the influenza virus. Among these, prevalence of influenza A(H3N2), influenza B, and H1N1pdm09 was 26.7, 6.3, and 10%, respectively. Nominal co-infections were detected. An easy to use commercial kit was used for the majority of the study after proper evaluation for sensitivity and specificity against a gold standard protocol. Specific diagnosis using molecular tools caters to the urgency, and a precise measure of the disease burden and management actions are needed, especially in developing countries like India. Infection rate estimation using a sensitive RT-PCR assay signified that influenza was highly prevalent in the region. The study data generated will help understand the epidemiology of influenza in India as well as generate information for global influenza surveillance and disease burden.

RESUMEN

Human metapneumovirus (HMPV) and human respiratory syncytial virus (HRSV) are ubiquitous respiratory viral pathogens. They belong to the family Paramyxoviridae (subfamily Pneumovirinae) and is responsible for acute respiratory tract infections in children, elderly and immunocompromised patients. We designed and tested a multiplex reverse transcriptase polymerase chain reaction (mRT-PCR) as a cost-effective alternative to real-time PCR and cell culture based detection for HMPV and HRSV. The newly developed PCR was used to screen nasal/throat swab samples from 356 patients with suspected acute respiratory infection attending the Government Medical College, Thiruvananthapuram, Kerala, India. The method was compared with a commercially available kit employing real time PCR, for its sensitivity and specificity. 53 (14.9 %) samples were positive for at least one tested pathogen by mRT-PCR. All except one among the positive samples showed similar pathogen profile when tested using real time PCR. 8 (15.1 %) among these 53 were positive for HRSVA, 33 (62.3 %) positive for HRSVB and 12 (22.6 %) were positive for HMPV. 17 (32.7 %) samples showed co-infections in them. Sensitivity and specificity of the mRT-PCR was comparable to that of the commercial kit. Our findings indicate that this newly developed mRT-PCR can be used as a cost-effective alternative for laboratory diagnosis of HMPV/HRSV infection and will significantly reduce diagnostic costs for these viruses in clinical settings.