Preparation and development of equine hyperimmune globulin F(ab')2 against severe acute respiratory syndrome coronavirus.
OBJECTIVE
The resurgence of severe acute respiratory syndrome (SARS) is still a threat because the causative agent remaining in animal reservoirs is not fully understood, and sporadic cases continue to be reported. Developing high titers of anti-SARS hyperimmune globulin to provide an alternative pathway for emergent future prevention and treatment of SARS.


METHODS
SARS coronavirus (CoV)F69 (AY313906) and Z2-Y3 (AY394989) were isolated and identified from 2 different Cantonese onset SARS patients. Immunogen was prepared from SARS-CoV F69 strain. Six health horses were immunized 4 times and serum was collected periodically to measure the profile of specific IgG and neutralizing antibodies using indirect enzyme-linked immunosorbent assay and a microneutralization test. Sera were collected in large amounts at the peak, where IgG was precipitated using ammonium sulphate and subsequently digested with pepsin. The product was then purified using anion-exchange chromatography to obtain F(ab')2 fragments.


RESULTS
The specific IgG and neutralizing antibody titers peaked at approximately week 7 after the first immunization, with a maximum value of 1:14210. The sera collected at the peak were then purified. Fragment of approximately 15 g F(ab')2 was obtained from 1litre antiserum and the purity was above 90% with the titer of 1:5120, which could neutralize the other strain (SARS-CoV Z2-Y3) as well.


CONCLUSIONS
This research provides a viable strategy for the prevention and treatment of SARS coronavirus infection with equine hyperimmune globulin, with the purpose of combating any resurgence of SARS.
Lu
Jia-Hai
JH
Sun Yat-sen University, Guangzhou 510080, China. jiahailu@yahoo.com.cn
Guo
Zhong-Min
ZM
Han
Wen-Yu
WY
Wang
Guo-Ling
GL
Zhang
Ding-Mei
DM
Wang
Yi-Fei
YF
Sun
Sheng-Yun
SY
Yang
Qin-He
QH
Zheng
Huan-Ying
HY
Wong
Bing L
BL
Zhong
Nan-Shan
NS
D000818:Animals; D000914:Antibodies, Viral / Q000737:chemistry / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D006736:Horses; D006801:Humans; D007106:Immune Sera / Q000276:immunology*; D007114:Immunization; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000302:isolation & purification*; D007074:Immunoglobulin G / Q000737:chemistry / Q000302:isolation & purification*; D009500:Neutralization Tests; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology* / Q000302:isolation & purification; D045169:Severe Acute Respiratory Syndrome / Q000821:virology
D000914:Antibodies, Viral; D007106:Immune Sera; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G