Carrier status of Streptococcus suis in the palatine tonsils of apparently healthy slaughtered pigs of India.

Streptococcus suis is an emerging bacterial pathogen of huge economic impact to the swine industry worldwide. The information regarding the carrier status of S. suis in the slaughtered pigs along with its genetic characterization is not available in Indian pig population, which needs to be addressed for the therapeutic and preventive measures. In the present study, 563 palatine tonsils of apparently healthy slaughtered pigs were probed for the prevalence, and genetic characterization of S. suis and prevalence were found to be 15.45% and 32.68% by bacteriological and molecular methods, respectively. In 87 isolates recovered, 6 cps-types were detected showing the predominance of serotype 7 (24.13%) and 5 (18.39%), whereas 11 cps-types were detected in tonsillar DNA involving cps-types 9 (28.26%) and 7 (14.13%) as the major serotypes with arcA+/sly+/epf+/mrp- being the prevalent genotype. The histopathological changes with the immunodetection of S. suis antigen confirmed its persistence in asymptomatic carriers. Of 87 bacterial isolates, 7 isolates (serotypes 7 & 2) were pathogenic to Swiss albino mice showing the classical lesions of meningitis and septicemia. The presence of virulent serotypes of S. suis in healthy slaughtered pigs suggests a great health risk to the people engaged in piggery operations and in-contact pigs.

Effect of inhibition of Toll-like receptor 3 signaling on pathogenesis of rabies virus in mouse model.

Rabies is a zoonotic viral disease with inevitably fatal outcome. Toll-like receptor 3 (TLR3) could sense dsRNA viral infections, and implicated in pathogenesis of rabies and Negri bodies (NBs) formation. Present study was undertaken to elucidate the role of TLR3 in pathogenesis, NBs formation, and therapeutic potential of blocking TLR3/dsRNA interaction in rabies infection. Young Swiss albino mice were infected with 100 LD50 of street rabies virus (SRABV) intracerebrally (i/c) on day 0 and treated with 30 µg of CU CPT 4a (selective TLR3 inhibitor) i/c on 0, 3 and 5 days post-infection (DPI). Three mice each were sacrificed at 1, 3, 5, 7, 9, 11, and 13 DPI to study sequential pathological consequences through histopathology, Seller's staining, immunofluorescence, immunohistochemistry, TUNEL assay, flow cytometry, and viral and cytokine genes quantification by real-time PCR. CU CPT 4a inhibited TLR3 expression resulted in delayed development and decreased intensity of clinical signs and pathological lesions, low viral load, significantly reduced NBs formation, and increased survival time in SRABV-infected mice. These parameters suggested that TLR3 did influence the SRABV replication and NBs formation. Inhibition of TLR3 led to decreased expression of pro-inflammatory cytokines and interferons indicated an anti-inflammatory effect of CU CPT 4a during SRABV infection. Further, TLR3-inhibited group revealed normal CD4+/CD8+ T-cells ratio with less TUNEL-positive apoptotic cells indicated that immune cell kinetics are not affected during TLR3-inhibition. SRABV-infected and mock-treated mice were developed severe clinical signs and histopathological lesions, more NBs formation, high viral load, increased pro-inflammatory cytokines expression in brain, which were correlated with higher expression levels of TLR3. In conclusion, these data suggested that TLR3/dsRNA signaling pathway could play critical role in pathogenesis of SRABV infection in vivo and opens up new avenues of therapeutics.

Swine coronaviruses (SCoVs) and their emerging threats to swine population, inter-species transmission, exploring the susceptibility of pigs for SARS-CoV-2 and zoonotic concerns.

Swine coronaviruses (SCoVs) are one of the most devastating pathogens affecting the livelihoods of farmers and swine industry across the world. These include transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine respiratory coronavirus (PRCV), porcine hemagglutinating encephalomyelitis virus (PHEV), swine acute diarrhea syndrome coronavirus (SADS-CoV), and porcine delta coronavirus (PDCoV). Coronaviruses infect a wide variety of animal species and humans because these are having single stranded-RNA that accounts for high mutation rates and thus could break the species barrier. The gastrointestinal, cardiovascular, and nervous systems are the primary organ systems affected by SCoVs. Infection is very common in piglets compared to adult swine causing high mortality in the former. Bat is implicated to be the origin of all CoVs affecting animals and humans. Since pig is the only domestic animal in which CoVs cause a wide range of diseases; new coronaviruses with high zoonotic potential could likely emerge in the future as observed in the past. The recently emerged severe acute respiratory syndrome coronavirus virus-2 (SARS-CoV-2), causing COVID-19 pandemic in humans, has been implicated to have animal origin, also reported from few animal species, though its zoonotic concerns are still under investigation. This review discusses SCoVs and their epidemiology, virology, evolution, pathology, wildlife reservoirs, interspecies transmission, spill-over events and highlighting their emerging threats to swine population. The role of pigs amid ongoing SARS-CoV-2 pandemic will also be discussed. A thorough investigation should be conducted to rule out zoonotic potential of SCoVs and to design appropriate strategies for their prevention and control.

Prophylactic and therapeutic insights into trained immunity: A renewed concept of innate immune memory.

Trained immunity is a renewed concept of innate immune memory that facilitates the innate immune system to have the capacity to remember and train cells via metabolic and transcriptional events to enable them to provide nonspecific defense against the subsequent encounters with a range of pathogens and acquire a quicker and more robust immune response, but different from the adaptive immune memory. Reversing the epigenetic changes or targeting the immunological pathways may be considered potential therapeutic approaches to counteract the hyper-responsive or hypo-responsive state of trained immunity. The efficient regulation of immune homeostasis and promotion or inhibition of immune responses is required for a balanced response. Trained immunity-based vaccines can serve as potent immune stimuli and help in the clearance of pathogens in the body through multiple or heterologous effects and confer protection against nonspecific and specific pathogens. This review highlights various features of trained immunity and its applications in developing novel therapeutics and vaccines, along with certain detrimental effects, challenges as well as future perspectives.

An updated review on bluetongue virus: epidemiology, pathobiology, and advances in diagnosis and control with special reference to India.

Bluetongue (BT) is an economically important, non-contagious viral disease of domestic and wild ruminants. BT is caused by BT virus (BTV) and it belongs to the genus Orbivirus and family Reoviridae. BTV is transmitted by Culicoides midges and causes clinical disease in sheep, white-tailed deer, pronghorn antelope, bighorn sheep, and subclinical manifestation in cattle, goats and camelids. BT is a World Organization for Animal Health (OIE) listed multispecies disease and causes great socio-economic losses. To date, 28 serotypes of BTV have been reported worldwide and 23 serotypes have been reported from India. Transplacental transmission (TPT) and fetal abnormalities in ruminants had been reported with cell culture adopted live-attenuated vaccine strains of BTV. However, emergence of BTV-8 in Europe during 2006, confirmed TPT of wild-type/field strains of BTV. Diagnosis of BT is more important for control of disease and to ensure BTV-free trade of animals and their products. Reverse transcription polymerase chain reaction, agar gel immunodiffusion assay and competitive enzyme-linked immunosorbent assay are found to be sensitive and OIE recommended tests for diagnosis of BTV for international trade. Control measures include mass vaccination (most effective method), serological and entomological surveillance, forming restriction zones and sentinel programs. Major hindrances with control of BT in India are the presence of multiple BTV serotypes, high density of ruminant and vector populations. A pentavalent inactivated, adjuvanted vaccine is administered currently in India to control BT. Recombinant vaccines with DIVA strategies are urgently needed to combat this disease. This review is the first to summarise the seroprevalence of BTV in India for 40 years, economic impact and pathobiology.