The effects of dietary supplement of arginine on protective humoral and cell-mediated immune responses of broiler chicks vaccinated and challenged against hydropericardium syndrome virus (HPSV) were investigated and compared with those of 2 reference drugs (cyclophosphamide and cyclosporine). Percentage ratios of lymphoid organs (bursa, spleen, and thymus) to BW, postvaccination and challenge serum antibody responses to HPSV, cutaneous basophil hypersensitivity reaction, peripheral lymphoproliferation, postchallenge detection of HPSV in the tissues of infected birds, and ability of chicks to resist virulent HPSV challenge were the parameters utilized to determine the effects of arginine on protective immune responses of chicks. A total of 600 chicks were used in this study. Arginine-supplemented chicks showed significant (P < 0.05) stimulation of lymphoproliferation and cutaneous basophil hypersensitivity reactions compared with untreated control chicks. Similarly, significantly higher body and lymphoid organ weights were (P < 0.05) recorded in arginine-supplemented chicks compared with untreated control chicks. The highest survival rate was recorded in arginine-supplemented HPS-vaccinated chicks compared with immune-suppressed (cyclophosphamide- and cyclosporine-treated and HPS-vaccinated chicks) and untreated unvaccinated control chicks after virulent HPSV challenges. Postchallenge tissue samples from arginine-supplemented and HPS-vaccinated chicks yielded negligible HPSV detections by virus isolation in cell culture or PCR method, or both, compared with untreated control chicks. Thus, it was concluded that dietary supplementation of arginine had beneficial effects on humoral and cell-mediated immune responses of broiler chicks against HPSV.

Background COVID-19 immunoglobulin G (IgG) antibodies have been considered to provide protective immunity and its immunoassays have been widely used for serosurveillance. In our serosurveillance on an industrial workforce of randomly selected 3296 subjects, COVID-19 IgG antibody positivity was reported in 7.37% (243) subjects. However, when 30 days later, eight of the 243 COVID-19 IgG antibody-positive individuals complained of symptoms suggestive of COVID-19 infection and were confirmed as COVID-19 infection by reverse transcription-polymerase chain reaction (RT-PCR), their COVID-19 IgG antibodies were retested. Seven of the eight previously IgG positive individuals had lost their protective antibodies. Methods Subsequently, a prospective clinical trial was planned by repeating the test for IgG antibodies on the remaining earlier positive 235 individuals at 45-65 days after their initial test. Only 201 of the 235 individuals consented and participated in the non-randomized single-arm observational trial. Results Only 28.36% (57/201) retained their IgG antibodies and 70.15% (141/201) had lost their IgG antibodies. Three cases reported equivocal results on retesting. Conclusions Our findings show that the protective COVID-19 IgG antibodies rapidly decline over one to three months. Further studies are needed with a quantitative assay over a period with neutralizing antibodies to establish if its decay can potentially lead to reinfections. Rapidly decaying protective IgG antibodies would impact herd immunity and vaccine durability. It is critical for the potential vaccines to generate both protective T-and Bcell immune responses in a sustained manner.

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Background Necrotising soft tissue infections (NSTI) are relatively common infections with high morbidity and mortality rate, as they often present late in their course. Quick and aggressive surgical treatment improves survival and decreases hospital stay.

Objective: We aimed to study the seroprevalence of coronavirus disease 2019 (COVID-19) and sustainability of the immune response in health care workers (HCWs). A cross-sectional study was conducted between October 7 and November 30, 2020, in a multi-specialty hospital in Eastern India designated as COVID hospital during this pandemic. Study participants included 2,110 HCWs, including those who have recovered from COVID infection. Method: HCWs were required to complete a questionnaire and give written consent to participate in the study. Their venous blood sample was collected for serum analysis of IgG antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by chemiluminescent immunoassay. Results: Positive IgG antibodies were seen in 924 participants with a point prevalence of 43.79%. Slightly higher reactivity was seen in males. History of COVID-19 infection was noted in 10.9%, with the highest antibody response in 81% cases. A maximum of 87.9% reactivity was seen in the first two months, and a significant fall was noted in the fourth month, with reactivity seen in only 50% of the study participants. Conclusion: SARS-CoV-2 infection is associated with a variable immune response in the infected population. The declining trend of the antibodies correlates with short-lived protective immunity and the possibility of re-infection. Further studies are needed to explore the probable reasons for varied seroprevalence.