• 식물병연구
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• 제11권1호
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• pp.28-34
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• 2005

이 연구에서는 파속패소에 발생하여 큰피해를 주는 흑색썩음균핵병에 대하여 경종적 방법에 의한 방제가능성을 모색하기 위하여 병든 마늘상의 병원균(균핵)의 밀도와 이병포장에서 토심별로 병원균의 밀도를 조사하였고, 파종깊이, 파종시기, 석회시용 등 경종적 요인이 병 발생에 미치는 영향을 검토하였다. 마늘 수확기에 토양 중 병원균의 밀도 및 분햐정도는 병원균의 종류에 따라 차이를 보였는데 소균핵균 Sclerotium cepivorum이 대균핵균 Scletotium sp.에 비해 형성 균핵수도 많고 덜 분해되었다. 마늘 재배포장에서의 병원균의 밀도는 토양 30g당 1~13개 수준에었고 토심이 깊어질수록 병원균의 밀도가 편저히 감소되는 것으로 나타났으며, 병원균은 토심 5cm 이내에 95% 이상 분포하는 것으로 나타났다. 마늘 재식깊이를 달리하여 파종했을 때 병 발생정돈느 재식깊이를 깊게 할수록 병 발생이 적었다. 국내에서 주로 재배되고 있는 마늘의 품종별 종구전염정도에 있어서는 한지형 마늘에 비하여 난지형 마늘에서 훨씬 높았는데, 난지형 마늘 중에서는 완도종에서 가장 높았고, 이어 대서종, 고당종, 남도종 순이었으며 고흥종에서는 종구전염이 확인되지 않았다. 마늘파종시기를 달리하여 종구를 파종한 결과, 10월 중순이전에 일찍 파종한 처리에서 10월말 이후에 늦게 파종한 처리에 비하여 병 발생이 낮았다. 한편 석회를 토양 kg당 100, 200, 300g 수준으로 시용할 경우 석회 시용량에 비례하여 병 발생이 감소되는 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1529-1538
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• 2017

Klebsiella pneumoniae is an opportunistic and clinically significant emerging pathogen. We investigated the relative roles of Toll-like receptor (TLR) 2 and TLR4 in initiating host defenses against K. pneumoniae. TLR2 knockout (KO), TLR4 KO, TLR2/4 double KO (DKO), and wild-type (WT) mice were inoculated with K. pneumoniae. Mice in each group were sacrificed after either 12 or 24h, and the lungs, liver, and blood were harvested to enumerate bacterial colony-forming units (CFU). Cytokine and chemokine levels were analyzed using enzyme-linked immunosorbent assay and real-time PCR, and pneumonia severity was determined by histopathological analysis. Survival was significantly shortened in TLR4 KO and TLR2/4 DKO mice compared with that of WT mice after infection with $5{\times}10^3CFU$. TLR2 KO mice were more susceptible to infection than WT mice after exposure to a higher infectious dose. Bacterial burdens in the lungs and liver were significantly higher in TLR2/4 DKO mice than in WT mice. Serum $TNF-{\alpha}$, MCP-1, MIP-2, and nitric oxide levels were significantly decreased in TLR2/4 DKO mice relative to those in WT mice, and TLR2/4 DKO mice showed significantly decreased levels of $TNF-{\alpha}$, IL-6, MCP-1, and inducible nitric oxide synthase mRNA in the lung compared with those in WT mice. Collectively, these data indicate that TLR2/4 DKO mice were more susceptible to K. pneumoniae infection than single TLR2 KO and TLR4 KO mice. These results suggest that TLR2 and TLR4 play cooperative roles in lung innate immune responses and bacterial dissemination, resulting in systemic inflammation during K. pneumoniae infection.

• IMMUNE NETWORK
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• 제24권2호
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• pp.7.1-7.19
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• 2024

Viral load and the duration of viral shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are important determinants of the transmission of coronavirus disease 2019. In this study, we examined the effects of viral doses on the lung and spleen of K18-hACE2 transgenic mice by temporal histological and transcriptional analyses. Approximately, 1×10⁵ plaque-forming units (PFU) of SARS-CoV-2 induced strong host responses in the lungs from 2 days post inoculation (dpi) which did not recover until the mice died, whereas responses to the virus were obvious at 5 days, recovering to the basal state by 14 dpi at 1×10² PFU. Further, flow cytometry showed that number of CD8+ T cells continuously increased in 1×10² PFU-virus-infected lungs from 2 dpi, but not in 1×10⁵ PFU-virus-infected lungs. In spleens, responses to the virus were prominent from 2 dpi, and number of B cells was significantly decreased at 1×10⁵ PFU; however, 1×1² PFU of virus induced very weak responses from 2 dpi which recovered by 10 dpi. Although the defense responses returned to normal and the mice survived, lung histology showed evidence of fibrosis, suggesting sequelae of SARS-CoV-2 infection. Our findings indicate that specific effectors of the immune response in the lung and spleen were either increased or depleted in response to doses of SARS-CoV-2. This study demonstrated that the response of local and systemic immune effectors to a viral infection varies with viral dose, which either exacerbates the severity of the infection or accelerates its elimination.