Evaluation of oral Lanzhou lamb rotavirus vaccine via passive transfusion with CD4(+)/CD8(+) T lymphocytes

T-Cell Responses after Rotavirus Infection or Vaccination in Children: A Systematic Review

Cellular immunity against rotavirus in children is incompletely understood. This review describes the current understanding of T-cell immunity to rotavirus in children. A systematic literature search was conducted in Embase, MEDLINE, Web of Science, and Global Health databases using a combination of “t-cell”, “rotavirus” and “child” keywords to extract data from relevant articles published from January 1973 to March 2020. Only seventeen articles were identified. Rotavirus-specific T-cell immunity in children develops and broadens reactivity with increasing age. Whilst occurring in close association with antibody responses, T-cell responses are more transient but can occur in absence of detectable antibody responses. Rotavirus-induced T-cell immunity is largely of the gut homing phenotype and predominantly involves Th1 and cytotoxic subsets that may be influenced by IL-10 Tregs. However, rotavirus-specific T-cell responses in children are generally of low frequencies in peripheral blood and are limited in comparison to other infecting pathogens and in adults. The available research reviewed here characterizes the T-cell immune response in children. There is a need for further research investigating the protective associations of rotavirus-specific T-cell responses against infection or vaccination and the standardization of rotavirus-specific T-cells assays in children.

Faecal shedding of rotavirus vaccine in Chinese children after vaccination with Lanzhou lamb rotavirus vaccine

Lanzhou lamb rotavirus vaccine (LLR) is an oral live attenuated vaccine first licensed in China in 2000. To date, > 60 million doses of LLR have been distributed to children. However, very little is known about faecal shedding of LLR in children. Therefore, faecal samples (n = 1,184) were collected from 114 children for 15 days post-vaccination in September–November 2011/2012. Faecal shedding and viral loads were determined by an enzyme immunoassay kit (EIA) and real-time RT-PCR. The complete genome was sequenced and the vaccine strain was isolated by culture in MA104 cells. Approximately 14.0% (16/114) of children had rotavirus-positive samples by EIA for at least 1 day post-vaccination. Viral loads in EIA-positive samples ranged from < 1.0 × 10³ to 1.9 × 10⁸ copies/g. Faecal shedding occurred as early as post-vaccination day 2 and as late as post-vaccination day 13 and peaked on post-vaccination day 5–10. One LLR strain was isolated by culture in MA104 cells. Sequence analysis showed 99% identity with LLR prototype strain. Faecal shedding of LLR in stool is common within 15 days of LLR vaccination, indicating vaccine strains can replicate in human enteric tissues.

Porcine circovirus type 1 was undetected in vaccine but could be cultured in the cell substrate of Lanzhou lamb rotavirus vaccine

In 2010, Rotarix was found to be contaminated with infectious porcine circovirus type 1 (PCV1). In China, the Lanzhou lamb rotavirus (LLR) vaccine is the only vaccine used to prevent rotavirus disease. From 2006 to September 2014, more than 54 million doses of LLR vaccines have been lot released. It is a safety issue whether PCV1 is present in the LLR vaccine. Although the cell substrate of LLR, bovine kidney (BK), is different from that of Rotarix, we have investigated the cell’s permissivity for PCV1 by both infectivity and full-length PCR analysis. We have assessed the LLR using a quantitative PCR (qPCR) assay. A total of 171 random batches of LLR final products over a period of 5 years were tested, and no PCV1 was detected (0/171). Infectivity studies showed that two strains of PCV1, the PCV1-prototype, which was derived from PK-15 cells, and the mutant, PCV1-GSK, which was isolated from Rotarix, were capable of replicating in BK cells over a wide m.o.i. ranging from 10 to 0.01. After culture for 6 days, copies of PCV1-prototype DNA were higher than those of PCV1-GSK on average. The genome of the virus was detected at 6 days post-infection. In summary, the LLR vaccine is free of PCV1. Nevertheless, because PCV1 can replicate in the BK cell substrate, manufacturers need to be vigilant in monitoring for this adventitious agent.

Immuno-enhancement effects of Yifei Tongluo Granules on cyclophosphamide-induced immunosuppression in Balb/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Yifei Tongluo Granules has been employed clinically with the combination of chemotherapy agents to treat patients with multidrug-resistant tuberculosis. However, the mechanisms underlying the therapeutic potential have not been well elucidated. The present study was employed to verify immunomodulatory effect and to investigate the underlying mechanisms which have not been explored.

MATERIALS AND METHODS

The study samples of total extracts (FB-E) and polysaccharides (FB-P) were prepared by the extraction of the Yifei Tongluo Granules using appropriate techniques. A simple immunodeficient mice model was established by challenging Balb/c mice with cyclophosphamide in order to avoid the handling of tuberculosis viruses. The in vivo study was thus designed to systematically elucidate the immuno-enhancement effects of Yifei Tongluo Granules extracts in immunosuppressed mice induced by cyclophosphamide. Balb/c mice were orally ingested once daily with the low and high doses of two different extracts for ten consecutive days, respectively, accompanied by intraperitoneal injection of cyclophosphamide (60mg/kg) on days 1-3 and 10.

RESULTS

Compared with the model group, the treatment of immunodeficient mice with the low and high doses of the extracts FB-E or FB-P enhanced spleen and thymus indices, T- and B-cell proliferation as well as increased the activities of splenic natural killer, lymphokine activated killer, cytotoxic T lymphocyte cells and peritoneal macrophage phagocytosis. In addition, the FB-E or FB-P treatment balanced the ratio of Th1/Th2 and up-regulated the CD4+/CD8+ ratio in the serum.

CONCLUSIONS

These results demonstrate, for the first time, that the treatment of the cyclophosphamide-challenged mice with the Yifei Tongluo Granules extracts resulted in accelerated recovery of immunosuppression, sugguesting that the immunomodulation might be the mechanism for the observed clinical benefits of Yifei Tongluo Granules. Our findings provide preliminary mechanistic study evidences for clinical application of Yifei Tongluo Granules in patients with immunodeficient diseases such as tuberculosis.

Detailed analysis of BALB/c mice challenged with wild type rotavirus EDIM provide an alternative for infection model of rotavirus

Mouse is one of the infection animal models for rotavirus. Since the optimal age of mouse sensitive to rotavirus infection thus far has not been unified, we elucidated clinical symptoms, immune responses and pathological changes of mice in different ages after challenged by murine rotavirus wild strain EDIM (Epidemic Diarrhea of Infant Mice) to provide data for the estimation. One-week-old, two-week-old, and three-week-old BALB/c mice were inoculated with EDIM in the challenge dose of 235 ID50, 470 ID50 and 705 ID50 respectively and were compared to mock-infected controls. Diarrhea illness, mobility, bodyweight were recorded, viral shedding and immune responses including serum IgA, fecal sIgA were detected, and small intestine tissue was evaluated for virus distribution and pathological changes. All the mice in one-week-old and two-week-old groups were completely unavoidable to be infected by EDIM and have been found to be malaise, activity reduced and even diarrhea, while three-week-old mice partly resist the challenge with 40% mice free from diarrhea. Meanwhile, EDIM infection has greater impact to the bodyweight of two-week-old group than those of one-week-old, three-week-old (0.9860 vs 1.2340, 1.2375g/day). One peak of virus shedding in three groups was observed in day 1-2 post infection, but the duration shortened with age increase. Feces sIgA in both two-week-old and three-week-old groups began to increase in day 4, 2-3days earlier than that in one-week-old group, and grow to the peak in day 8, which is about 2 fold of that in one-week-old group. Stronger serum IgA response was found in two-week-old group, it increased to the peak in day 15 and the level was 2 fold of three-week-old group and 4 fold of one-week-old group. The pathological changes included vacuolar degeneration, edema and congestion of intestinal wall, integrity destruction of enteric epithelium, and the changes relieved with the increase of age. Besides, rotavirus particles were found in small intestine tissues, especially in the surface and crypt of villi. In conclusion, the two-week-old mice were more sensitive to EDIM infection and initiated more effective immune response. In combination with that 14days old mice equals to 2 months infant when the first dose of rotavirus vaccine should be administrated, two-week-old mice is preferred to be used as infection model for the study of pathogenicity and immunogenicity of rotavirus.