Changes in the spike and nucleocapsid protein of porcine epidemic diarrhea virus strain in Vietnam-a molecular potential for the vaccine development?

BACKGROUND: Porcine epidemic diarrhea virus (PEDV) is a dangerous virus causing large piglet losses. PEDV spread rapidly between pig farms and caused the death of up to 90% of infected piglets. Current vaccines are only partially effective in providing immunity to suckling due to the rapid dissemination and ongoing evolution of PEDV. METHODS: In this study, the complete genome of a PEDV strain in Vietnam 2018 (IBT/VN/2018 strain) has been sequenced. The nucleotide sequence of each fragment was assembled to build a continuous complete sequence using the DNASTAR program. The complete nucleotide sequences and amino acid sequences of S, N, and ORF3 genes were aligned and analyzed to detect the mutations. RESULTS: The full-length genome was determined with 28,031 nucleotides in length which consisted of the 5'UTR, ORF1ab, S protein, ORF3, E protein, M protein, N protein, and 3'UTR region. The phylogenetic analysis showed that the IBT/VN/2018 strain was highly virulent belonged to the G2b subgroup along with the Northern American and Asian S-INDEL strains. Multiple sequence alignment of deduced amino acids revealed numerous mutations in the S, N, and ORF3 regions including one substitution 766P > L766 in the epitope SS6; two in the S0subdomain (135DN136 > 135SI136 and N144> D144); two in subdomain SHR1 at aa 1009L > M1009 and 1089S > L1089; one at aa 1279P > S1279 in subdomain SHR2 of the S protein; two at aa 364N > I364 and 378N > S378 in the N protein; four at aa 25L > S25, 70I > V70, 107C > F107, and 168D > N168 in the ORF3 protein. We identified two insertions (at aa 59NQGV62 and aa 145N) and one deletion (at aa 168DI169) in S protein. Remarkable, eight amino acid substitutions (294I > M294, 318A > S318, 335V > I335, 361A > T361, 497R > T497, 501SH502 > 501IY502, 506I > T506, 682V > I682, and 777P > L777) were found in SA subdomain. Besides, N- and O-glycosylation analysis of S, N, and ORF3 protein reveals three known sites (25G+, 123N+, and 62V+) and three novel sites (144D+, 1009M+, and 1279L+) in the IBT/VN/2018 strain compared with the vaccine strains. Taken together, the results showed that mutations in the S, N, and ORF3 genes can affect receptor specificity, viral pathogenicity, and the ability to evade the host immune system of the IBT/VN/2018 strain. Our results highlight the importance of molecular characterization of field strains of PEDV for the development of an effective vaccine to control PEDV infections in Vietnam.

Genome analysis and phylogenetic characterization of two deformed wing virus strains from Apis cerana in Vietnam.

BACKGROUND: Deformed wing virus (DWV) is a virulent virus that causes honeybee disease. DWV can exist as a latent infection in honeybees, outbreak into epidemics, and cause serious damage to beekeeping cross the world, including Vietnam. METHODS: The two DWV strains circulating in Vietnamese honeybee, Apis cerana, were first isolated from adult honeybees in North Vietnam (DWV-NVN) and South Vietnam (DWV-SVN). Their complete nucleotide sequences were determined, aligned, and compared with other DWV strains. RESULTS: The two Vietnamese DWV strains comprised 10,113 bp and contained a large single open reading frame (ORF) of 2,893 amino acids, initiating at nucleotide 1,130 and terminating at nucleotide 9,812. Multiple nucleotide sequence alignment between these two DWV-VN strains and DWV strains in A. mellifera was performed. The DWV-VN strains showed a low genetic identity (from 91.4% to 92.0%) with almost of these strains, but lower identities (89.2% and 89.4%) with UK2 and (89.6%) with the China2 strain. Low identities (91.7% and 91.9%) were also observed between the China3 strain (in A. cerana) and the DWV-VN strains, respectively. The deduced amino acid sequence alignment showed high genetic similarities (97.0%-97.9%) when the USA1, Chile, Italy1, France, UK1, UK2, Japan, Korea2, China1, China2 and China3 strains were compared to the DWV-VN strains. This ratio was 96.7% and 96.8% when the Korea1 strain was compared to the DWV-SVN and DWV-NVN strains, respectively. Numerous amino acid substitutions were identified in the L, VP3, and RdRp sequences. Notably, we observed six substitutions positioned at amino acids 27 (E > I), 98 (S > T), 120 (A > V), 153 (M > T), 170 (D > F), and 174 (Y > F) in the L protein, two amino acid changes at positions 980 (S > A) and 1032 (E > T) in VP3, and one amino acid change at position 2627 (R > C) unique to the DWV-VN strains. Phylogenetic analysis based on complete genome sequences, RdRp sequences and Simplot analysis indicated that there was a significant difference between DWV-VN strains in A. cerana and DWV strains in A. mellifera. The results suggested that the genetic variations of the DWV-VN strains in A. cerana help them to adapt geographical conditions and may lead to change the viral pathogenicity of DWV-VN strains.

Case-fatality and functional status three months after first-ever stroke in Vietnam.

BACKGROUND: To provide novel information on outcomes after first-ever stroke in Vietnam, case-fatality and functional status were assessed 3months after stroke onset. METHODS: First-ever stroke patients admitted to the stroke unit of a tertiary teaching hospital in Ho Chi Minh City, Vietnam were recruited, examined and interviewed. Functional status was assessed on the modified Rankin Scale (mRS) at admission and again at 3months. RESULT: We recruited 450 consecutive first-ever stroke patients (99.6% participation, 47.9% female, mean age 62.5 [SD 14.0] years, 76.2% ischaemic stroke). Three-month observed case-fatality was 10.4%. Under plausible assumptions about deaths among non-recruited participants, the estimated case-fatality would be higher (16.4%) Those who had died were mostly older patients compromised by comorbidities and pre-existing disability, and who had severe impairment or severe disability due to stroke at the time of admission. At 3-month follow-up of 376 patients, 34% had least severe disability (mRS=0/1), 39% had intermediate disability and 28% had most severe disability (mRS=4/5). Those with least severe disability were mostly men younger than 65years of age and principally with ischemic stroke. Those with most severe disability were predominantly women aged ≥65years and those with severe disability, mainly attributable to intracerebral haemorrhage. At 3months, 50% had better functional status than at stroke onset, and 27% had poorer function. CONCLUSION: Case-fatality was relatively low in this study, possibly because of cultural preferences for end-of-life care at home. The dependency burden was relatively high, placing pressure on the healthcare system and society.

Health-related quality of life after stroke: reliability and validity of the Duke Health Profile for use in Vietnam.

INTRODUCTION: Health-related quality of life (HRQoL) is commonly used to assess outcomes after stroke. The Duke Health Profile (DHP) has been translated and culturally adapted for use in Vietnam, but its reliability and validity for use with stroke patients in Vietnam or elsewhere have not been assessed. METHODS: First-ever stroke patients (n = 108) who were admitted to 115 People's Hospital between February and September 2012 and survived for 3 months after stroke had HRQoL assessed using the DHP and a comparison instrument (EQ-5D). Caregivers of 94 patients completed these questionnaires as a proxy. After 1 week, these questionnaires were re-administered to patients and proxies. RESULTS: The mean differences between test and retest assessments of HRQoL by patients were small and not clinically meaningful and were not consistently associated with sex, age, type of stroke or severity of impairment or disability. Direct assessments by the patient were on average greater than those obtained from the proxy. The ICCs ranged from 0.60 to 0.86 (patient test-retest) and from 0.55 to 0.98 (patient-proxy agreement). The ICCs were greatest for physical functioning components (patient test-retest 0.63-0.86, patient-proxy 0.69-0.98). The correlations between the DHP dimensions and EQ-5D were generally stronger when they measured similar constructs (r = 0.53-0.66) and were lower for less related constructs (r = 0.11-0.43). CONCLUSION: The DHP has moderate reliability and validity for use with stroke patients in Vietnam even when information is obtained from proxy respondents.