National Institute of Virology, 20-A Dr Ambedkar Road, Pune-411001, Maharashtra, India.
Virol J. 2011 Feb 1;8:46. doi: 10.1186/1743-422X-8-46.
Difference in severity of dengue outbreaks has been related to virus serotype, genotype and clades within genotypes. Till the 1980 s, India and Sri Lanka reported low number of dengue hemorrhagic fever (DHF) cases despite circulation of all four serotypes of dengue virus (DENV). Since the 1990 s the occurrence of DHF has increased. The increase has been attributed to changes in virus lineage especially with regard to DENV-2 and DENV-3. DENV-1 has been associated with dengue fever (DF) outbreaks and DENV-4 reports have been rare. The emergence of DENV-4 was reported recently in 2003 in Delhi and in 2007 in Hyderabad. The last report of DENV-4 from Maharashtra was in 1975 from Amalner.
We report on the detection of DENV-4 in Pune, Maharashtra after an absence of almost 30 years. Two cases were detected in 2009-10, serotyped by multiplex reverse transcriptase polymerase chain reaction (RT-PCR). Both the cases were recorded as severe dengue (Category 3) requiring intensive care unit (ICU) level of treatment. Depending on the hemagglutination inhibiting (HI) antibody titres the 2009 case was characterized as a primary infection and the 2010 case as a secondary infection. Both the cases presented plasma leakage and neither showed any kind of haemorrhage. The 2009 case survived while the 2010 case was fatal. An isolate was obtained from the 2009 case. Based on envelope (E) gene sequence analysis, the virus belonged to genotype I of DENV-4, and clustered with isolates from India and Sri Lanka and was distant from the isolates from Thailand. The nucleotide and amino acid diversity of the E gene of the Indian isolates increased from 1996 to 2007 to 2009 in context of the E gene sequences of other isolates belonging to genotype I.
The increasing diversity in the circulating DENV-4 calls for close monitoring of the DENV-4 serotype.
登革热病毒（DENV）血清型、基因型和基因型内的分支在登革热暴发的严重程度上存在差异。尽管所有四种登革热病毒（DENV）都在传播，但直到 20 世纪 80 年代，印度和斯里兰卡报告的登革出血热（DHF）病例数量仍然很少。自 20 世纪 90 年代以来，DHF 的发生有所增加。这种增加归因于病毒谱系的变化，特别是 DENV-2 和 DENV-3。DENV-1 与登革热（DF）暴发有关，DENV-4 的报告很少。DENV-4 的出现是在 2003 年德里和 2007 年海得拉巴最近报告的。马哈拉施特拉邦最后一次报告 DENV-4 是在 1975 年的阿马尔纳。
我们报告了马哈拉施特拉邦浦那在几乎 30 年没有出现后检测到 DENV-4。2009-10 年检测到两例，通过多重逆转录聚合酶链反应（RT-PCR）进行血清型鉴定。两例均为重症登革热（第 3 类），需要重症监护病房（ICU）级别的治疗。根据血凝抑制（HI）抗体滴度，2009 例为原发性感染，2010 例为继发性感染。两例均有血浆渗漏，均无任何出血。2009 例患者存活，2010 例患者死亡。从 2009 年的病例中获得了一个分离物。根据包膜（E）基因序列分析，该病毒属于 DENV-4 基因型 I，与来自印度和斯里兰卡的分离株聚类，并与来自泰国的分离株较远。与属于基因型 I 的其他分离株的 E 基因序列相比，2009 年印度分离株的 E 基因核苷酸和氨基酸多样性在 1996 年至 2007 年至 2009 年有所增加。
循环 DENV-4 的多样性增加需要密切监测 DENV-4 血清型。
